Surgical Anatomy

by Joseph Maclise

THE FORM OF THE THORACIC CAVITY, AND THE POSITION OF THE LUNGS, HEART, AND LARGER BLOODVESSELS.

In the human body there does not exist any such space as cavity, properly so called. Every space is occupied by its contents. The thoracic space is completely filled by its viscera, which, in mass, take a perfect cast or model of its interior. The thoracic viscera lie so closely to one another, that they respectively influence the form and dimensions of each other. That space which the lungs do not occupy is filled by the heart, &c., and vice versa. The thoracic apparatus causes no vacuum by the acts of either contraction or dilatation. Neither do the lungs or the heart. When any organ, by its process of growth, or by its own functional act, forces a space for itself, it immediately inhabits that space entirely at the expense of neighbouring organs. When the heart dilates, the pulmonary space contracts; and when the thoracic space increases, general space diminishes in the same ratio.

The mechanism of the functions of respiration and circulation consists, during the life of the animal, in a constant oscillatory nisus to produce a vacuum which it never establishes. These vital forces of the respiratory and circulatory organs, so characteristic of the higher classes of animals, are opposed to the general forces of surrounding nature. The former vainly strive to make exception to the irrevocable law, that “nature abhors a vacuum.” This act of opposition between both forces constitutes the respiratory act, and thus the respiratory thoracic being (like a vibrating pendulum) manifests respiratory motion, not as an effort of volition originating solely with itself, but according to the measure of the force of either law; as entity is relationary, so is functionality likewise. The being is functional by relationship; and just as a pendulum is functional, by reason of the counteraction of two opposing forces,—viz., the force of motion and the force of gravity,—so is a thoracic cavity (considering it as a mechanical apparatus) functional by two opposing forces—the vital force and the surrounding physical force. The inspiration of thoracic space is the expiration of general space, and reciprocally.

The thoracic space is a symmetrical enclosure originally, which aftercoming necessities modify and distort in some degree. The spaces occupied by the opposite lungs in the adult body do not exactly correspond as to capacity, O O, Plate 1. Neither is the cardiac space, A E G D, Plate 1, which is traversed by the common median line, symmetrical. The asymmetry of the lungs is mainly owing to the form and position of the heart; for this organ inclines towards the left thoracic side. The left lung is less in capacity than the right, by so much space as the heart occupies in the left pulmonary side. The general form of the thorax is that of a cone, I I N N, Plate 1, bicleft through its perpendicular axis, H M. The line of bicleavage is exactly median, and passes through the centre of the sternum in front, and the centres of the dorsal vertebral behind. Between the dorsal vertebral and the sternum, the line of median cleavage is maintained and sketched out in membrane. This membranous middle is formed by the adjacent sides of the opposite pleural or enveloping bags in which the lungs are enclosed. The heart, A, Plate 1, is developed between these two pleural sacs, F F, and separates them from each other to a distance corresponding to its own size. The adjacent sides of the two pleural sacs are central to the thorax, and form that space which is called mediastinum; the heart is located in this mediastinum, U E, Plate 1. The extent of the thoracic region ranges perpendicularly from the root of the neck, Q, Plate 1, to the roof of the abdomen—viz., the diaphragm, P, transversely from the ribs of one side, I N, Plate 1, to those of the other, and antero-posteriorly from the sternum, H M, to the vertebral column. All this space is pulmonary, except the cardiac or median space, which, in addition to the heart, A, Plate 1, and great bloodvessels, G C B, contains the oesophagus, bronchi, &c. The ribs are the true enclosures of thoracic space, and, generally, in mammalian forms, they fail or degenerate at that region of the trunk which is not pulmonary or respiratory. In human anatomy, a teleological reason is given for this—namely, that of the ribs being mechanically subservient to the function of respiration alone. But the transcendental anatomists interpret this fact otherwise, and refer it to the operation of a higher law of formation.

The capacity of the thorax is influenced by the capacity of the abdomen and its contents. In order to admit of full inspiration and pulmonary expansion, the abdominal viscera recede in the same ratio as the lungs dilate. The diaphragm, P P, Plate 1, or transverse musculo-membranous partition which divides the pulmonary and alimentary cavities, is, by virtue of its situation, as mechanically subservient to the abdomen as to the thorax. And under general notice, it will appear that even the abdominal muscles are as directly related to the respiratory act as those of the thorax. The connexion between functions is as intimate and indissoluble as the connexion between organs in the same body. There can be no more striking proof of the divinity of design than by such revelations as anatomical science everywhere manifests in facts such as this—viz., that each organ serves in most cases a double, and in many a triple purpose, in the animal economy.

The apex of the lung projects into the root of the neck, even to a higher level, Q, Plate 1, than that occupied by the sternal end of the clavicle, K. If the point of a sword were pushed through the neck above the clavicle, at K, Plate 1, it would penetrate the apex of the right lung, where the subclavian artery, Q, Plate 1, arches over it. In connexion with this fact, I may mention it as very probable that the bruit, or continuous murmur which we hear through the stethoscope, in chlorotic females, is caused by the pulsation of the subclavian artery against the top of the lung. The stays or girdle which braces the loins of most women prevents the expansion of the thoracic apparatus, naturally attained by the descent of the diaphragm; and hence, no doubt, the lung will distend inordinately above towards the neck. It is an interesting fact for those anatomists who study the higher generalizations of their science, that at those very localities—viz., the neck and loins, where the lungs by their own natural effort are prone to extend themselves in forced inspiration—happen the “anomalous” creations of cervical and lumbar ribs. The subclavian artery is occasionally complicated by the presence of these costal appendages.

If the body be transfixed through any one of the intercostal spaces, the instrument will surely wound some part of the lung. If the thorax be pierced from any point whatever, provided the instrument be directed towards a common centre, A, Plate 1, the lung will suffer lesion; for the heart is, almost completely, in the healthy living body, enveloped in the lungs. So true is it that all the costal region (the asternal as well as the sternal) is a pulmonary enclosure, that any instrument which pierces intercostal space must wound the lung.

As the sternal ribs degenerate into the “false” asternal or incomplete ribs from before, obliquely backward down to the last dorsal vertebra, so the thoracic space takes form. The lungs range through a much larger space, therefore, posteriorly than they do anteriorly.

The form of the thorax, in relation to that of the abdomen, may be learned from the fact that a gunshot, which shall enter a little below N, Plate 1, and, after traversing the body transversely, shall pass out at a corresponding point at the opposite side, would open the thorax and the abdomen into a common cavity; for it would pierce the thorax at N, the arching diaphragm at the level of M, and thereat enter the belly; then it would enter the thorax again at P, and make exit below N, opposite. If a cutting instrument were passed horizontally from before backward, a little below M, it would first open the abdomen, then pierce the arching diaphragm, and pass into the thorax, opposite the ninth or eighth dorsal vertebra.

The outward form or superficies masks in some degree the form of the interior. The width of the thorax above does not exceed the diameter between the points I I, of Plate 1, or the points W W, of Plate 2. If we make percussion directly from before backwards at any place external to I, Plate 1, we do not render the lung vibrative. The diameters between I I and N N, Plate 1, are not equal; and these measures will indicate the form of the thorax in the living body, between the shoulders above and the loins below.

The position of the heart in the thorax varies somewhat with several bodies. The size of the heart, even in a state of perfect health, varies also in subjects of corresponding ages, a condition which is often mistaken for pathological. For the most part, its form occupies a space ranging from two or three lines right of the right side of the sternum to the middle of the shafts of the fifth and sixth ribs of the left side. In general, the length of the osseous sternum gives the exact perpendicular range of the heart, together with its great vessels.

The aorta, C, Plates 1 and 2, is behind the upper half of the sternum, from which it is separated by the pericardium, D, Plate 1, the thin edge of the lung, and the mediastinal pleurae, U E, Plate 1, &c. If the heart be injected from the abdominal aorta, the aortal arch will flatten against the sternum. Pulmonary space would not be opened by a penetrating instrument passed into the root of the neck in the median line above the sternum, at L, Plate 1. But the apices of both lungs would be wounded if the same instrument entered deeply on either side of this median line at K K. An instrument which would pierce the sternum opposite the insertion of the second, third, or fourth costal cartilage, from H downwards, would transfix some part of the arch of the aorta, C, Plate 1. The same instrument, if pushed horizontally backward through the second, third, or fourth interspaces of the costal cartilages close to the sternum, would wound, on the right of the sternal line, the vena cava superior, G, Plate 1; on the left, the pulmonary artery, B, and the descending thoracic aorta. In the healthy living body, the thoracic sounds heard in percussion, or by means of the stethoscope, will vary according to the locality operated upon, in consequence of the variable thickness of those structures (muscular and osseous, &c.,) which invest the thoracic walls. Uniformity of sound must, owing to these facts, be as materially interrupted, as it certainly is, in consequence of the variable contents of the cavity. The variability of the healthy thoracic sounds will, therefore, be too often likely to be mistaken for that of disease, if we forget to admit these facts, as instanced in the former state. Considering the form of the thoracic space in reference to the general form of the trunk of the living body, I see reason to doubt whether the practitioner can by any boasted delicacy of manipulation, detect an abnormal state of the pulmonary organs by percussion, or the use of the stethoscope, applied at those regions which he terms coracoid, scapulary, subclavian, &c., if the line of his examination be directed from before backwards. The scapula, covered by thick carneous masses, does not lie in the living body directly upon the osseous-thorax, neither does the clavicle. As all antero-posterior examination in reference to the lungs external to the points, I I, between the shoulders cannot, in fact, concern the pulmonary organs, so it cannot be diagnostic of their state either in health or disease. The difficulties which oppose the practitioner’s examination of the state of the thoracic contents are already numerous enough, independent of those which may arise from unanatomical investigation.

DESCRIPTION OF PLATES 1 & 2.

PLATE 1.

A. Right ventricle of the heart.

B. Origin of pulmonary artery.

C. Commencement of the systemic aorta, ascending part of aortic arch.

D. Pericardium investing the heart and the origins of the great bloodvessels.

E. Mediastinal pleura, forming a second investment for the heart, bloodvessels, &c.

F. Costal pleura, seen to be continuous above with that which forms the mediastinum.

G. Vena cava superior, entering pericardium to join V, the right auricle.

H. Upper third of sternum.

I I. First ribs.

K K. Sternal ends of the clavicles.

L. Upper end of sternum.

M. Lower end of sternum.

N N. Fifth ribs.

O O. Collapsed lungs.

P P. Arching diaphragm.

Q. Subclavian artery.

R. Common carotid artery, at its division into internal and external carotids.

S S. Great pectoral muscles.

T T. Lesser pectoral muscles.

U. Mediastinal pleura of right side.

V. Right auricle of the heart.

Plate 1

PLATE 2.

A. Right ventricle of the heart. A a. Pericardium.

B. Pulmonary artery. B b. Pericardium.

C. Ascending aorta. C c. Transverse aorta.

D. Right auricle.

E. Ductus arteriosus in the loop of left vagus nerve, and close to phrenic nerve of left side.

F. Superior vena cava.

G. Brachio-cephalic vein of left side.

H. Left common carotid artery.

I. Left subclavian vein.

K. Lower end of left internal jugular vein.

L. Right internal jugular vein.

M. Right subclavian vein.

N. Innominate artery—brachio-cephalic.

O. Left subclavian artery crossed by left vagus nerve.

P. Right subclavian artery crossed by right vagus nerve, whose inferior laryngeal branch loops under the vessel.

Q. Right common carotid artery

R. Trachea.

S. Thyroid body.

T. Brachial plexus of nerves.

U. Upper end of left internal jugular vein.

V V. Clavicles cut across and displaced downwards.

W W. The first ribs.

X X. Fifth ribs cut across.

Y Y. Right and left mammae.

Z. Lower end of sternum.

Plate 2

COMMENTARY ON PLATES 3 & 4.

THE SURGICAL FORM OF THE SUPERFICIAL CERVICAL AND FACIAL REGIONS, AND THE RELATIVE POSITION OF THE PRINCIPAL BLOOD-VESSELS, NERVES, &c.

When the neck is extended in surgical position, as seen in Plates 3 and 4, its general outline assumes a quadrilateral shape, approaching to a square. The sides of this square are formed anteriorly by the line ranging from the mental symphysis to the top of the sternum, and posteriorly by a line drawn between the occiput and shoulder. The superior side of this cervical square is drawn by the horizontal ramus of the lower maxilla, and the inferior side by the horizontal line of the clavicle. This square space, R 16, 8, 6, Plate 4, is halved by a diagonal line, drawn by the sterno-cleido-mastoid muscle B, which cuts the square into two triangles. In the anterior triangle, F 16, 6, Plate 4, is located the superficial common carotid artery, C, and its branches, D, with accompanying nerves. In the posterior triangle, 9, 8, 6, Plate 4, is placed the superficial subclavian artery, A, its branches, L M, and the brachial plexus of nerves, I. Both these triangles and their contents are completely sheathed by that thin scarf-like muscle, named platysma myoides, A A, Plate 3, the fibres of which traverse the neck slantingly in a line, O A, of diagonal direction opposite to and secant of that of the sterno-mastoid muscle.

When the skin and subcutaneous adipose membrane are removed by careful dissection from the cervical region, certain structures are exposed, which, even in the undissected neck, projected on the superficies, and are the unerring guides to the localities of the blood-vessels and nerves, &c. In Plate 4, the top of the sternum, 6; the clavicle, 7; the “Pomum Adami,” 1; the lower maxilla at V; the hyoid bone, Z; the sterno-cleido-mastoid muscle, B; and the clavicular portion of the trapezius muscle, 8; will readily be felt or otherwise recognised through the skin, &c. When these several points are well considered in their relation to one another, they will correctly determine the relative locality of those structures—the blood-vessels, nerves, &c., which mainly concern the surgical operation.

The middle point, between 7, the clavicle, and 6, the sternum, of Plate 4, is marked by a small triangular space occurring between the clavicular and sternal divisions of the sterno-cleido-mastoid muscle. This space marks the situation (very generally) of the bifurcation of the innominate artery into the subclavian and common carotid arteries of the right side; a penetrating instrument would, if passed into this space at an inch depth, pierce first the root of the internal jugular vein, and under it, but somewhat internal, the root of either of these great arterial vessels, and would wound the right vagus nerve, as it traverses this region. For some extent after the subclavian and carotid vessels separate from their main common trunk, they lie concealed beneath the sterno-mastoid muscle, B, Plate 4, and still deeper beneath the sternal origins of the sterno-hyoid muscle, 5, and sterno-thyroid muscle, some of whose fibres are traceable at the intervals. The omo-hyoid muscle and the deep cervical fascia, as will be presently seen, conceal these vessels also.

The subclavian artery, A, Plate 4, first appears superficial to the above-named muscles of the cervical region just at the point where, passing from behind the scalenus muscle, N, Plate 4, which also conceals it, it sinks behind the clavicle. The exact locality of the artery in this part of its course would be indicated by a finger’s breadth external to the clavicular attachment of the sterno-mastoid muscle. The artery passes beneath the clavicle at the middle of this bone, a point which is indicated in most subjects by that cellular interval occurring between the clavicular origins of the deltoid and great pectoral muscles.

The posterior cervical triangle, 9, 8, 7, Plate 4, in which the subclavian artery is situated, is again subdivided by the muscle omo-hyoid into two lesser regions, each of which assumes somewhat of a triangular shape. The lower one of these embraces the vessel, A, and those nerves of the brachial plexus, I, which are in contact with it. The posterior belly of the omo-hyoid muscle, K, and the anterior scalenus muscle, N, form the sides and apex of this lesser triangular space, while the horizontal clavicle forms its base. This region of the subclavian artery is well defined in the necks of most subjects, especially when the muscles are put in action. In lean but muscular bodies, it is possible to feel the projection of the anterior scalenus muscle under the skin, external to the sterno-mastoid. The form of the omo-hyoid is also to be distinguished in the like bodies. But in all subjects may be readily recognised that hollow which occurs above the clavicle, and between the trapezius, 8, and the sterno cleido-mastoid, 7 B, in the centre of which hollow the artery lies.

The contents of the larger posterior cervical triangle, formed by B, the sterno-mastoid before; 9, the splenius; and 8, the trapezius behind, and by the clavicle below, are the following mentioned structures—viz., A, the subclavian artery, in the third part of its course, as it emerges from behind N, the scalenus anticus; L, the transversalis colli artery, a branch of the thyroid axis, which will be found to cross the subclavian vessel at this region; I, the brachial plexus of nerves, which lie external to and above the vessel; H, the external jugular vein, which sometimes, in conjunction with a plexus of veins coming from behind the trapezius muscle, entirely conceals the artery; M, the posterior scapular artery, a branch of the subclavian, given off from the vessel after it has passed from behind the scalenus muscle; O, numerous lymphatic glands; P, superficial descending branches of the cervical plexus of nerves; and Q, ascending superficial branches of the same plexus. All these structures, except some of the lymphatic glands, are concealed by the platysma myoides A, as seen in Plate 3, and beneath this by the cervical fascia, which latter shall be hereafter more clearly represented.

In somewhat the same mode as the posterior half of the omo-hyoid subdivides the larger posterior triangle into two of lesser dimensions, the anterior half of the same muscle divides the anterior triangle into two of smaller capacity.

The great anterior triangle, which is marked as that space inclosed within the points, 6, the top of the sternum, the mental symphysis and the angle of the maxilla; and whose sides are marked by the median line of the neck before, the sterno-mastoid behind, and the ramus of the jaw above, contains C, the common carotid artery, becoming superficial from beneath the sterno-mastoid muscle, and dividing into E, the internal carotid, and D, the external carotid. The anterior jugular vein, 3, also occupies this region below; while some venous branches, which join the external and internal jugular veins, traverse it in all directions, and present obstacles to the operator from their meshy plexiform arrangement yielding, when divided, a profuse haemorrhage.

The precise locality at which the common carotid appears from under the sterno-mastoid muscle is, in almost all instances, opposite to the thyroid cartilage. At this place, if an incision, dividing the skin, platysma and some superficial branches of nerves, be made along the anterior border of the sterno-mastoid muscle, and this latter be turned a little aside, a process of cervical fascia, and beneath it the sheath of the carotid artery, will successionally disclose themselves. In many bodies, however, some degree of careful search requires to be made prior to the full exposure of the vessel in its sheath, in consequence of a considerable quantity of adipose tissue, some lymphatic glands, and many small veins lying in the immediate vicinity of the carotid artery and internal jugular vein. This latter vessel, though usually lying completely concealed by the sterno-mastoid muscle, is frequently to be seen projecting from under its fore part. In emaciated bodies, where the sterno-mastoid presents wasted proportions, it will, in consequence, leave both the main blood-vessels uncovered at this locality in the neck.

The common carotid artery ascends the cervical region almost perpendicularly from opposite the sterno-clavicular articulation to the greater cornu of the os hyoides. For the greater part of this extent it is covered by the sterno-mastoid muscle; but as this latter takes an oblique course backwards to its insertion into the mastoid process, while the main blood-vessel dividing into branches still ascends in its original direction, so is it that the artery becomes uncovered by the muscle. Even the root of the internal carotid, E, may be readily reached at this place, where it lies on the same plane as the external carotid, but concealed in great part by the internal jugular vein. It would be possible, while relaxing the sterno-mastoid muscle, to compress either the common carotid artery or its main branches against the cervical vertebral column, if pressure were made in a direction backwards and inwards. The facial artery V, which springs from the external carotid, D, may be compressed against the horizontal ramus of the lower jaw-bone at the anterior border of the masseter muscle. The temporal artery, as it ascends over the root of the zygoma, may be compressed effectually against this bony point.

The external jugular vein, H, Plate 4, as it descends the neck from the angle of the jaw obliquely backwards over the sterno-mastoid muscle, may be easily compressed and opened in any part of its course. This vein courses downwards upon the neck in relation to that branch of the superficial cervical plexus, named auricularis magnus nerve, Q, Plate 4, G, Plate 3. The nerve is generally situated behind the vein, to which it lies sometimes in close proximity, and is liable, therefore, to be accidentally injured in the performance of phlebotomy upon the external jugular vein. The coats of the external jugular vein, E, Plate 3, are said to hold connexion with some of the fibres of the platysma-myoides muscle, A A, Plate 3, and that therefore, if the vessel be divided transversely, the two orifices will remain patent for a time.

The position of the carotid artery protects the vessel, in some degree, against the suicidal act, as generally attempted. The depth of the incision necessary to reach the main blood-vessels from the fore part of the neck is so considerable that the wound seldom effects more than the opening of some part of the larynx. The ossified condition of the thyroid and cricoid parts of the laryngeal apparatus affords a protection to the vessels. The more oblique the incision happens to be, the greater probability is there that the wound is comparatively superficial, owing to the circumstance of the instrument having encountered one or more parts of the hyo-laryngeal range; but woeful chance sometimes directs the weapon horizontally through that membranous interval between the thyroid and hyoid pieces, in which case, as also in that where the laryngeal pieces persist permanently cartilaginous, the resistance to the cutting instrument is much less.

The anatomical position of the parotid, H, Plate 3, and submaxillary glands, W, Plate 4, is so important, that their extirpation, while in a state of disease, will almost unavoidably concern other principal structures. Whether the diseased parotid gland itself or a lymphatic body lying in connexion with it, be the subject of operation, it seldom happens that the temporo-maxillary branch of the external carotid, F, escapes the knife. But an accident, much more liable to occur, and one which produces a great inconvenience afterwards to the subject, is that of dividing the portio-dura nerve, S, Plate 4, at its exit from the stylo-mastoid foramen, the consequence being that almost all the muscles of facial expression become paralyzed. The masseter, L, Plate 3, pterygoid, buccinator, 15, Plate 4, and the facial fibres of the platysma muscles, A O, Plate 3, still, however, preserve their power, as these structures are innervated from a different source. The orbicularis oculi muscle, which is principally supplied by the portio-dura nerve, is paralyzed, though it still retains a partial power of contraction, owing to the anatomical fact that some terminal twigs of the third or motor pair of nerves of the orbit branch into this muscle.

The facial artery, V, and the facial vein, U, Plate 4, are in close connexion with the submaxillary gland. Oftentimes they traverse the substance of it. The lingual nerve and artery lie in some part of their course immediately beneath the gland. The former two are generally divided when the gland is excised; the latter two are liable to be wounded in the same operation.

DESCRIPTION OF PLATES 3 & 4.

PLATE 3.

A A A. Subcutaneous platysma myoides muscle, lying on the face, neck, and upper part of chest, and covering the structures contained in the two surgical triangles of the neck.

B. Lip of the thyroid cartilage.

C. Clavicular attachment of the trapezius muscle.

D. Some lymphatic bodies of the post triangle.

E. External jugular vein.

F. Occipital artery, close to which are seen some branches of the occipitalis minor nerve of the cervical plexus.

G. Auricularis magnus nerve of the superficial cervical plexus.

H. Parotid gland.

I. Temporal artery, with its accompanying vein.

K. Zygoma.

L. Masseter muscle, crossed by the parotid duct, and some fibres of platysma.

M. Facial vein.

N. Buccinator muscle.

O. Facial artery seen through fibres of platysma.

P. Mastoid half of sterno-mastoid muscle.

Q. Locality beneath which the commencements of the subclavian and carotid arteries lie.

R. Locality of the subclavian artery in the third part of its course.

S. Locality of the common carotid artery at its division into internal and external carotids.

Plate 3

PLATE 4.

A. Subclavian artery passing beneath the clavicle, where it is crossed by some blood-vessels and nerves.

B. Sternal attachment of the sterno-mastoid muscle, marking the situation of the root of common carotid.

C. Common carotid at its point of division, uncovered by sterno-mastoid.

D. External carotid artery branching into lingual, facial, temporal, and occipital arteries.

E. Internal carotid artery.

F. Temporo-maxillary branch of external carotid artery.

G. Temporal artery and temporal vein, with some ascending temporal branches of portio-dura nerve.

H. External jugular vein descending from the angle of the jaw, where it is formed by the union of temporal and maxillary veins.

I. Brachial plexus of nerves in connexion with A, the subclavian artery.

K. Posterior half of the omo-hyoid muscle.

L. Transversalis colli artery.

M. Posterior scapular artery.

N. Scalenus anticus muscle.

O. Lymphatic bodies of the posterior triangle of neck.

P. Superficial descending branches of the cervical plexus of nerves.

Q. Auricularis magnus nerve ascending to join the portio-dura.

R. Occipital artery, accompanied by its nerve, and also by some branches of the occipitalis minor nerve, a branch of cervical plexus.

S. Portio-dura, or motor division of seventh pair of cerebral nerves.

T. Parotid duct.

U. Facial vein.

V. Facial artery.

W. Submaxillary gland.

X. Digastric muscle.

Y. Lymphatic body.

Z. Hyoid bone.

1. Thyroid cartilage.

2. Superior thyroid artery.

3. Anterior jugular vein.

4. Hyoid half of omo-hyoid muscle.

5. Sterno-hyoid muscle.

6. Top of the sternum.

7. Clavicle.

8. Trapezius muscle.

9. Splenius capitis and colli muscle.

10. Occipital half of occipito-frontalis muscle.

11. Levator auris muscle.

12. Frontal half of occipito-frontalis muscle.

13. Orbicularis oculi muscle.

14. Zygomaticus major muscle.

15. Buccinator muscle.

16. Depressor anguli oris muscle.

(Page 16)

Plate 4

COMMENTARY ON PLATES 5 & 6.

THE SURGICAL FORM OF THE DEEP CERVICAL AND FACIAL REGIONS, AND THE RELATIVE POSITION OF THE PRINCIPAL BLOODVESSELS AND NERVES, &c.

While the human cervix is still extended in surgical position, its deeper anatomical relations, viewed as a whole, preserve the quadrilateral form. But as it is necessary to remove the sterno-cleido-mastoid muscle, in order to expose the entire range of the greater bloodvessels and nerves, so the diagonal which that muscle forms, as seen in Plates 3 and 4, disappears, and thus both the cervical triangles are thrown into one common region. Although, however, the sterno-mastoid muscle be removed, as seen in Plate 5, still the great bloodvessels and nerves themselves will be observed to divide the cervical square diagonally, as they ascend the neck from the sterno-clavicular articulation to the ear.

The diagonal of every square figure is the junction line of the opposite triangles which form the square. The cervical square being indicated as that space which lies within the mastoid process and the top of the sternum—the symphysis of the lower maxilla and the top of the shoulder, it will be seen, in Plate 5, that the line which the common carotid and internal jugular vein occupy in the neck, is the diagonal; and hence the junction line of the two surgical triangles.

The general course of the common carotid artery and internal jugular vein is, therefore, obliquely backwards and upwards through the diagonal of the cervical square, and passing, as it were, from the point of one angle of the square to that of the opposite—viz., from the sterno-clavicular junction to the masto-maxillary space; and, taking the anterior triangle of the cervical square to be that space included within the points marked H 8 A, Plate 5, it will be seen that the common carotid artery ranges along the posterior side of this anterior triangle. Again: taking the points 5 Z Y to mark the posterior triangle of the cervical square, so will it be seen that the internal jugular vein and the common carotid artery, with the vagus nerve between them, range the anterior side of this posterior triangle, while the subclavian artery, Q, passes through the centre of the inferior side of the posterior triangle, that is, under the middle of the shaft of the clavicle.

The main blood vessels (apparently according to original design) will be found always to occupy the centre of the animal fabric, and to seek deep-seated protection under cover of the osseous skeleton. The vertebrae of the neck, like those of the back and loins, support the principal vessels. Even in the limbs the large bloodvessels range alongside the protective shafts of the bones. The skeletal points are therefore the safest guides to the precise localities of the bloodvessels, and such points are always within the easy recognition of touch and sight.

Close behind the right sterno-clavicular articulation, but separated from it by the sternal insertions of the thin ribbon-like muscles named sterno-hyoid and thyroid, together with the cervical fascia, is situated the brachio-cephalic or innominate artery, A B, Plates 5 and 6, having at its outer side the internal jugular division of the brachio-cephalic vein, W K, Plate 5. Between these vessels lies the vagus nerve, E, Plate 6, N, Plate 5. The common carotid artery, internal jugular vein, and vagus nerve, hold in respect to each other the same relationship in the neck, as far upwards as the angle of the jaw. While we view the general lateral outline of the neck, we find that, in the same measure as the blood vessels ascend from the thorax to the skull, they recede from the fore-part of the root of the neck to the angle of the jaw, whereby a much greater interval occurs between them and the mental symphysis, or the apex of the thyroid cartilage, than happens between them and the top of the sternum, as they lie at the root of the neck. This variation as to the width of the interval between the vessels and fore-part of the neck, in these two situations, is owing to two causes, 1st, the somewhat oblique course taken by the vessels from below upwards; 2dly, the projecting development of the adult lower jaw-bone, and also of the laryngeal apparatus, which latter organ, as it grows to larger proportions in the male than in the female, will cause the interval at this place to be much greater in the one than the other. In the infant, the larynx is of such small size, as scarcely to stand out beyond the level of the vessels, viewed laterally.

The internal jugular vein is for almost its entire length covered by the sterno-mastoid muscle, and by that layer of the cervical aponeurosis which lies between the vessels and the muscle. The two vessels, K C, Plate 5, with the vagus nerve, are enclosed in a common sheath of cellular membrane, which sends processes between them so as to isolate the structures in some degree from one another.

The trunk of the common carotid artery is in close proximity to the vagus nerve, this latter lying at the vessel’s posterior side. The internal jugular vein, which sometimes lies upon and covering the carotid, will be found in general separated from it for a little space. Opposite the os hyoides, the internal jugular vein lies closer to the common carotid than it does farther down towards the root of the neck. Opposite to the sterno-clavicular articulation, the internal jugular vein will be seen separated from the common carotid for an interval of an inch and more in width, and at this interval appears the root of the subclavian artery, B, Plates 5 and 6, giving off its primary branches, viz., the thyroid axis, D, the vertebral and internal mammary arteries, at the first part of its course.

The length of the common carotid artery varies, of course, according to the place where the innominate artery below divides, and also according to that place whereat the common carotid itself divides into internal and external carotids. In general, the length of the common carotid is considerable, and ranges between the sterno-clavicular articulation and the level of the os hyoides; throughout the whole of this length, it seldom or never happens that a large arterial branch is given off from the vessel, and the operation of ligaturing the common carotid is therefore much more likely to answer the results required of that proceeding than can be expected from the ligature of any part of the subclavian artery which gives off large arterial branches from every part of its course.

The sympathetic nerve, R, Plate 6, is as close to the carotid artery behind, as the vagus nerve, N, Plate 5, and is as much endangered in ligaturing this vessel. The branch of the ninth nerve, E, Plate 5, (descendens noni,) lies upon the common carotid, itself or its sheath, and is likely to be included in the ligature oftener than we are aware of.

The trunk of the external carotid, D, Plate 5, is in all cases very short, and in many bodies can scarcely be said to exist, in consequence of the thyroid, lingual, facial, temporal, and occipital branches, springing directly from almost the same point at which the common carotid gives off the internal carotid artery. The internal carotid is certainly the continuation of the common arterial trunk, while the vessel named external carotid is only a series of its branches. If the greater size of the internal carotid artery, compared to that of the external carotid, be not sufficient to prove that the former is the proper continuation of the common carotid, a fact may be drawn from comparative philosophy which will put the question beyond doubt, namely—that as the common carotid follows the line of the cervical vertebrae, just as the aorta follows that of the vertebrae of the trunk, so does the internal carotid follow the line of the cephalic vertebrae. I liken, therefore, those branches of the so-called external carotid to be, as it were, the visceral arteries of the face and neck. It would be quite possible to demonstrate this point of analogy, were this the place for analogical reasoning.

The common carotid, or the internal, may be compressed against the rectus capitis anticus major muscle, 13, Plate 6, as it lies on the fore-part of the vertebral column. The internal maxillary artery, 16, Plate 6, and the facial artery, G, Plate 5, are those vessels which bleed when the lower maxilla is amputated. In this operation, the temporal artery, 15, Plate 6, will hardly escape being divided also, it lies in such close proximity to the neck and condyle of the jaw-bone.

The subclavian artery, B Q, Plate 5, traverses the root of the neck, in an arched direction from the sterno-clavicular articulation to the middle of the shaft of the clavicle, beneath which it passes, being destined for the arm. In general, this vessel rises to a level considerably above the clavicle; and all that portion of the arching course which it makes at this situation over the first rib has become the subject of operation. The middle of this arching subclavian artery is (by as much as the thickness of the scalenus muscle, X, Plate 5) deeper situated than either extremity of the arch of this vessel, and deeper also than any part of the common carotid, by the same fact. So many branches spring from all parts of the arch of the subclavian artery, that the operation of ligaturing this vessel is less successful than the same operation exercised on others.

The structures which lie in connexion with the arch of the subclavian also render the operation of tying the vessel an anxious task. It is crossed and recrossed at all points by large veins, important nerves, and by its own principal branches. The vagus nerve, S E, Plate 6, crosses it at B, its root; external to which place the large internal jugular vein, K, Plate 5, lies upon it; external to this latter, the scalenus muscle, X, Plate 5, with the phrenic nerve lying upon the muscle, binds it fixedly to the first rib; more external still, the common trunk of the external jugular and shoulder veins, U, Plate 5, lie upon the vessel, and it is in the immediate vicinity of the great brachial plexus of nerves, P P, which pass down along its humeral border, many branches of the same plexus sometimes crossing it anteriorly.

The depth at which the middle of the subclavian artery lies may be learned by the space which those structures, beneath which it passes, necessarily occupy. The clavicle at its sternal end is round and thick, where it gives attachment to the sterno-cleido-mastoid muscle. The root of the internal jugular vein, when injected, will be seen to occupy considerable space behind the clavicle; and the anterior scalenus muscle is substantial and fleshy. The united spaces occupied by these structures give the depth of the subclavian artery in the middle part of its course.

The length of the subclavian artery between its point of branching from the innominate and that where it gives off its first branches varies in different bodies, but is seldom so extensive as to assure the operator of the ultimate success of the process of ligaturing the vessel. Above and below D, Plate 6, the thyroid axis, come off the vertebral and internal mammary arteries internal and anterior to the scalenus muscle. External and posterior to the scalenus, a large vessel, the post scapular, G, Plate 6, R, Plate 5, arises. If an aneurism attack any part of this subclavian arch, it must be in close connexion with some one of these branches. If a ligature is to be applied to any part of the arch, it will seldom happen that it can be placed farther than half an inch from some of these principal collateral branches.

When the shoulder is depressed, the clavicle follows it, and the subclavian artery will be more exposed and more easily reached than if the shoulder be elevated, as this latter movement raises the clavicle over the locality of the vessel. Dupuytren alludes practically to the different depths of the subclavian artery in subjects with short necks and high shoulders, and those with long necks and pendent shoulders. When the clavicle is depressed to the fullest extent, if then the sterno-cleido-mastoid and scalenus muscles be relaxed by inclining the head and neck towards the artery, I believe it may be possible to arrest the flow of blood through the artery by compressing it against the first rib, and this position will also facilitate the operation of ligaturing the vessel.

The subclavian vein, W, Plate 5, is removed to some distance from the artery, Q, Plate 5. The width of the scalenus muscle, X, separates the vein from the artery. An instance is recorded by Blandin in which the vein passed in company with the artery under the scalenus muscle.

DESCRIPTION OF PLATES 5 & 6.

PLATE 5.

A. Innominate artery at its point of bifurcation.

B. Subclavian artery crossed by the vagus nerve.

C. Common carotid artery with the vagus nerve at its outer side, and the descendens noni nerve lying on it.

D. External carotid artery.

E. Internal carotid artery with the descendens noni nerve lying on it.

F. Lingual artery passing under the fibres of the hyo-glossus muscle.

G. Tortuous facial artery.

H. Temporo-maxillary artery.

I. Occipital artery crossing the internal carotid artery and jugular vein.

K. Internal jugular vein crossed by some branches of the cervical plexus, which join the descendens noni nerve.

L. Spinal accessory nerve, which pierces the sterno-mastoid muscle, to be distributed to it and the trapezius.

M.Cervical plexus of nerves giving off the phrenic nerve to descend the neck on the outer side of the internal jugular vein and over the scalenus muscle.

N. Vagus nerve between the carotid artery and internal jugular vein.

O. Ninth or hypoglossal nerve distributed to the muscles of the tongue.

P P. Branches of the brachial plexus of nerves.

Q. Subclavian artery in connexion with the brachial plexus of nerves.

R R. Post scapular artery passing through the brachial plexus.

S. Transversalis humeri artery.

T. Transversalis colli artery.

U. Union of the post scapular and external jugular veins, which enter the subclavian vein by a common trunk.

V. Post-half of the omo-hyoid muscle.

W. Part of the subclavian vein seen above the clavicle.

X. Scalenus muscle separating the subclavian artery from vein.

Y. Clavicle.

Z. Trapezius muscle.

1. Sternal origin of sterno-mastoid muscle of left side.

2. Clavicular origin of sterno-mastoid muscle of right side turned down.

3. Scalenus posticus muscle.

4. Splenius muscle.

5. Mastoid insertion of sterno-mastoid muscle.

6. Internal maxillary artery passing behind the neck of lower jaw-bone.

7. Parotid duct.

8. Genio-hyoid muscle.

9. Mylo-hyoid muscle, cut and turned aside.

10. Superior thyroid artery.

11. Anterior half of omo-hyoid muscle.

12. Sterno-hyoid muscle, cut.

13. Sterno-thyroid muscle, cut.

Plate 5

PLATE 6.

A. Root of the common carotid artery.

B. Subclavian artery at its origin.

C. Trachea.

D. Thyroid axis of the subclavian artery.

E. Vagus nerve crossing the origin of subclavian artery.

F. Subclavian artery at the third division of its arch.

G. Post scapular branch of the subclavian artery.

H. Transversalis humeri branch of subclavian artery.

I. Transversalis colli branch of subclavian artery.

K. Posterior belly of omo-hyoid muscle, cut.

L. Median nerve branch of brachial plexus.

M. Musculo-spiral branch of same plexus.

N. Anterior scalenus muscle.

O. Cervical plexus giving off the phrenic nerve, which takes tributary branches from brachial plexus of nerves.

P. Upper part of internal jugular vein.

Q. Upper part of internal carotid artery.

R. Superior cervical ganglion of sympathetic nerve.

S. Vagus nerve lying external to sympathetic nerve, and giving off t its laryngeal branch.

T. Superior thyroid artery.

U. Lingual artery separated by hyo-glossus muscle from

V. Lingual or ninth cerebral nerve.

W. Sublingual salivary gland.

X. Genio-hyoid muscle.

Y. Mylo-hyoid muscle, cut and turned aside.

Z. Thyroid cartilage.

1. Upper part of sterno-hyoid muscle.

2. Upper part of omo-hyoid muscle.

3. Inferior constrictor of pharynx.

4. Cricoid cartilage.

5. Crico-thyroid muscle.

6. Thyroid body.

7. Inferior thyroid artery of thyroid axis.

8. Sternal tendon of sterno-mastoid muscle, turned down.

9. Clavicular portion of sterno-mastoid muscle, turned down.

10. Clavicle.

11. Trapezius muscle.

12. Scalenus posticus muscle.

13. Rectus capitis anticus major muscle.

14. Stylo-hyoid muscle, turned aside.

15. Temporal artery.

16. Internal maxillary artery.

17. Inferior dental branch of fifth pair of cerebral nerves.

18. Gustatory branch of fifth pair of nerves.

19. External pterygoid muscle.

20. Internal pterygoid muscle.

21. Temporal muscle cut to show the deep temporal branches of fifth pair of nerves.

22. Zygomatic arch.

23. Buccinator muscle, with buccal nerve and parotid duct.

24. Masseter muscle cut on the lower maxilla.

25. Middle constrictor of pharynx.

Plate 6

COMMENTARY ON PLATES 7 & 8.

THE SURGICAL DISSECTION OF THE SUBCLAVIAN AND CAROTID REGIONS, THE RELATIVE ANATOMY OF THEIR CONTENTS.

A perfect knowledge of the relative anatomy of any of the surgical regions of the body must include an acquaintance with the superposition of parts contained in each region, as well as the plane relationship of organs which hold the same level in each layer or anatomical stratum. The dissections in Plates 7 and 8 exhibit both these modes of relation. A portion of each of those superficial layers, which it was necessary to divide, in order to expose a deeper organ, has been left holding its natural level. Thus the order of superposition taken by the integument, the fasciae, the muscles, bones, veins, nerves, and arteries, which occupy both the surgical triangles of the neck, will be readily recognised in the opposite Plates.

The depth of a bloodvessel or other organ from surface will vary for many reasons, even though the same parts in the natural order of superposition shall overlie the whole length of the vessel or organ which we make search for. The principal of those reasons are:—1st, that the stratified organs themselves vary in thickness at several places; 2d, that the organ or vessel which we seek will itself incline to surface from deeper levels occupied elsewhere; 3d, that the normal undulations of surface will vary the depth of the particular vessels, &c.; and 4th, that the natural mobility of the superimposed parts will allow them to change place in some measure, and consequently influence the relative position of the object of search. On this account it is that the surgical anatomist chooses to give a fixed position to the subject about to be operated on, in order to reduce the number of these difficulties as much as possible.

In Plate 7 will be seen the surgical relationship of parts lying in the vicinity of the common carotid artery, at the point of its bifurcation into external and internal carotids. At this locality, the vessel will be found, in general, subjacent to the following mentioned structures, numbered from the superficies to its own level—viz., the common integument and subcutaneous adipose membrane, which will vary in thickness in several individuals; next, the platysma myoides muscle, F L, which is identified with the superficial fascia, investing the outer surface of the sterno-mastoid muscle; next, the deeper layer of the same fascia, R S., which passes beneath the sterno-mastoid muscle, but over the sheath of the vessels; and next, the sheath of the vessels, Q, which invests them and isolates them from adjacent structures. Though the vessel lies deeper than the level of the sterno-mastoid muscle at this locality, yet it is not covered by the muscle in the same manner, as it is lower down in the neck. At this place, therefore, though the actual depth of the artery from surface will be the same, whether it be covered or uncovered by the sterno-mastoid muscle, still we know that the locality of the vessel relative to the parts actually superimposed will vary accordingly. This observation will apply to the situation and relative position of all the other vessels as well. Other occurrences will vary the relations of the artery in regard to superjacent structures, though the actual depth of the vessel from surface may be the same. If the internal jugular vein covers the carotid artery, as it sometimes does, or if a plexus of veins, gathering from the fore-part of the neck or face, overlie the vessel, or if a chain of lymphatic bodies be arranged upon it, as is frequently the case, the knowledge of such occurrences will guard the judgment against being led into error by the conventionalities of the descriptive method of anatomists. The normal relative anatomy of the bloodvessels is taken by anatomists to be the more frequent disposition of their main trunks and branches, considered per se, and in connexion with neighbouring parts. But it will be seen by this avowal that those vessels are liable to many various conditions; and such is the case, in fact. No anatomist can pronounce with exactness the precise figure of vessels or other organs while they lie concealed beneath the surface. An approach to truth is all that the best experience can boast of. The form and relations of the carotid vessels of Plate 7 may or may not be the same as those concealed beneath the same region of Plate 8, at the point R.

The motions of the head upon the neck, or of the neck upon the trunk, will influence the relative position of the vessels A C B, of Plate 7, and therefore we take a fixed surgical position, in the expectation of finding that the carotid artery projects from under the anterior border of the upper third of the sterno-mastoid muscle, opposite the upper border of the thyroid cartilage; at this situation of the vessels, viz., R, Plate 8, opposite O, the thyroid projection, is in general to be found the anatomical relation of the vessels as they appear dissected in Plate 7. Of these vessels, the main trunks are less liable to anomalous character than the minor branches.

The relative position of the subclavian artery is as liable to be influenced by the motions of the clavicle on the sternum, as that of the carotid is by the motions of the lower jaw-bone on the skull, or by the larynx, in its own motions at the fore-part of the neck. It becomes as necessary, therefore, in the performance of surgical operations upon the subclavian artery, to fix the clavicle by depressing it, as in Plate 8, as it is to give fixity to the lower maxilla and larynx, in the position of Plate 7, when the carotid is the subject of operation.

The same named structures, but different as to their parts, will be found to overlie the subclavian artery as are found to conceal the carotid artery. The skin, the fascia, and platysma muscle, the sterno-cleido-mastoid muscle, the deep layer of the cervical fascia, &c., cover both vessels. One additional muscle binds down the subclavian artery, viz., the scalenus anticus. The omo-hyoid relates to both vessels, the anterior division to the carotid, the posterior to the subclavian.

The carotid artery lies uncovered by the sterno-mastoid muscle, opposite to the upper border of the thyroid cartilage, or the hyoid bone; and the subclavian artery emerges from under cover of a different part of the same muscle, opposite the middle of the clavicle. These points of relationship to the skeletal parts can be ascertained by the touch, in both instances, even in the undissected body. The thyroid point, O, of Plate 8, indicates the line, R N, which the carotid artery traverses in the same figure, along the anterior border of the sterno-mastoid muscle, as seen in the dissected region of Plate 7. The mid-point of the clavicle, U, Plate 7, and the top of the sternum in the same figure, will, while the eye follows the arching line, Z X T V, indicate with correctness the arching course of the subclavian, such as is represented in the dissection of that vessel, B, Plate 8.

The subclavian artery has no special sheath, properly so called; but the deep layer of the cervical fascia, P, Plate 8, which passes under A, the clavicular portion of the sterno-mastoid muscle, and becomes of considerable thickness and density, sheaths over the vessel in this region of its course.

A very complex condition of the veins which join the external jugular at this part of the course of the subclavian artery is now and then to be found overlying that vessel. If the hemorrhage consequent upon the opening of these veins, or that of the external jugular, be so profuse as to impede the operation of ligaturing the subclavian artery, it may in some measure be arrested by compressing them against the resisting parts adjacent, when the operator, feeling for D, the scalenus muscle, and the first rib to which it is attached, cannot fail to alight upon the main artery itself, B, Plate 8.

The middle of the shaft of the clavicle is a much safer guide to the vessel than are the muscles which contribute to form this posterior triangle of the neck, in which the subclavian vessel is located. The form or position of the clavicle in the depressed condition of the shoulder, as seen in Plate 8, is invariable; whereas that of the trapezius and sterno-mastoid muscles is inconstant, these muscles being found to stand at unequal intervals from each other in several bodies. The space between the insertions of both these muscles is indefinite, and may vary in degrees of width from the whole length of the clavicle to half an inch; or, as in some instances, leaving no interval whatever. The position of the omo-hyoid muscle will not be accounted a sure guide to the locality of the subclavian artery, since, in fact, it varies considerably as to its relationship with that vessel. The tense cords of the brachial plexus of nerves, F, Plate 8, which will be found, for the most part, ranging along the acromial border of the artery, are a much surer guide to the vessel.

On comparing the subclavian artery, at B, Plate 8, with the common carotid artery, at A, Plate 7, I believe that the former will be found to exhibit, on the whole a greater constancy in respect to the following-mentioned condition—viz., a single main arterial trunk arches over the first rib to pass beneath the middle of the clavicle, while the carotid artery opposite the thyroid piece of the larynx is by no means constantly single as a common carotid trunk. The place of division of the common carotid is not definite, and, therefore, the precise situation in the upper two-thirds of the neck, where it may present as a single main vessel, cannot be predicted with certainty in the undissected body. There is no other main artery of the body more liable to variation than that known as external carotid. It is subject to as many changes of character in respect to the place of its branching from the common carotid, and also in regard to the number of its own branches, as any of the lesser arteries of the system. It is but as an aggregate of the branches of that main arterial trunk which ranges from the carotid foramen of the temporal bone to the aorta; and, as a branch of a larger vessel, it is, therefore, liable to spring from various places of the principal trunk, just as we find to be the case with all the other minor branches of the larger arteries. Its name, external carotid, is as unfittingly applied to it, in comparison with the vessel from which it springs, as the name external subclavian would be if applied to the thyroid axis of the larger subclavian vessel. The nomenclature of surgical anatomy does not, however, court a philosophical inquiry into that propriety of speech which comparative science demands, nor is it supposed to be necessary in a practical point of view.

It will, however, sound more euphoneously with reason, and at the same time, I believe, be found not altogether unrelated to the useful, if, when such conditions as the “anomalies of form” present themselves, we can advance an interpretation of the same, in addition to the dry record of them as isolated facts. Comparative anatomy, which alone can furnish these interpretations, will therefore prove to be no alien to the practical, while it may lend explanation to those bizarreries which impede the way of the anthropotomist. All the anomalies of form, both as regards the vascular, the muscular, and the osseous systems of the human body, are analyzed by comparison through the animal series. Numerous cases are on record of the subclavian artery being found complicated with supernumerary ribs jutting from the 5th, 6th, or 7th cervical vertebrae. [Footnote] To these I shall add another, in respect of the carotid arteries—viz., that I have found them complicated with an osseous shaft of bone, taking place of the stylo-hyoid ligament, a condition which obtains permanently in the ruminant and other classes of mammals.

[Footnote: I have given an explanation of these facts in my work on Comparative Osteology and the Archetype Skeleton, to which, and also to Professor Owen’s work, entitled Homologies of the Vertebrate Skeleton, I refer the reader.]

DESCRIPTION OF PLATES 7 & 8.

PLATE 7.

A. Common carotid at its place of division.

B. External carotid.

C. Internal carotid, with the descending branch of the ninth nerve lying on it.

D. Facial vein entering the internal jugular vein.

E. Sterno-mastoid muscle, covered by

F. Part of the platysma muscle.

G. External jugular vein.

H. Parotid gland, sheathed over by the cervical fascia.

I. Facial vein and artery seen beneath the facial fibres of the platysma.

K. Submaxillary salivary gland.

L. Upper part of the platysma muscle cut.

M. Cervical fascia cut.

N. Sterno-hyoid muscle.

O. Omo-hyoid muscle.

P. Sterno-thyroid muscle.

Q. Fascia proper of the vessels.

R. Layer of the cervical fascia beneath the sterno-mastoid muscle.

S. Portion of the same fascia.

T. External jugular vein injected beneath the skin.

U. Clavicle at the mid-point, where the subclavian artery passes beneath it.

V. Locality of the subclavian artery in the third part of its course.

W. Prominence of the trapezius muscle.

X. Prominence of the clavicular portion of the sterno-cleido-mastoid muscle.

Y. Place indicating the interval between the clavicular and sternal insertions of sterno-cleido-mastoid muscle.

Z. Projection of the sternal portion of the sterno-cleido-mastoid muscle.

Plate 7

PLATE 8.

A. Clavicular attachment of the sterno-mastoid muscle lying over the internal jugular vein, &c.

B. Subclavian artery in the third part of its course.

C. Vein formed by the union of external jugular, scapular, and other veins.

D. Scalenus anticus muscle stretching over the artery, and separating it from the internal jugular vein.

E. Post-half of omo-hyoid muscle.

F. Inner branches of the brachial plexus of nerves.

G. Clavicular portion of trapezius muscle.

H. Transversalis colli artery.

I. Layer of the cervical fascia, which invests the sterno-mastoid and trapezius muscles.

K. Lymphatic bodies lying between two layers of the cervical fascia.

L. Descending superficial branches of the cervical plexus of nerves.

M. External jugular vein seen under the fascia which invests the sterno-mastoid muscle.

N. Platysma muscle cut on the body of sterno-mastoid muscle.

O. Projection of the thyroid cartilage.

P. Layer of the cervical fascia lying beneath the clavicular portion of the sterno-mastoid muscle.

Q. Layer of the cervical fascia continued from the last over the subclavian artery and brachial plexus of nerves.

Plate 8

COMMENTARY ON PLATES 9 & 10.

THE SURGICAL DISSECTION OF THE STERNO-CLAVICULAR OR TRACHEAL REGION, AND THE RELATIVE POSITION OF ITS MAIN BLOODVESSELS, NERVES, &c.

The law of symmetry governs the development of all structures which compose the human body; and all organized beings throughout the animal kingdom are produced in obedience to this law. The general median line of the human body is characterized as the point of fusion of the two sides; and all structures or organs which range this common centre are either symmetrically azygos, or symmetrically duplex. The azygos organ presents as a symmetrical unity, and the duplex organ as a symmetrical duality. The surgical anatomist takes a studious observation of this law of symmetry; and knowing it to be one of general and almost unexceptional occurrence, he practises according to its manifestation.

The vascular as well as the osseous skeleton displays the law of symmetry; but while the osseous system offers no exception to this law, the vascular system offers one which, in a surgical point of view, is of considerable importance—namely, that behind the right sterno-clavicular articulation, C, Plate 9, is found the artery, A, named innominate, this being the common trunk of the right common carotid and subclavian vessels; while on the left side, behind the left sterno-clavicular junction, Q, Plate 10, the two vessels (subclavian, B, and carotid, A,) spring separately from the aortic arch. This fact of asymmetrical arrangement in the arterial trunks at the fore part of the root of the neck is not, however, of invariable occurrence; on the contrary, numerous instances are observed where the arteries in question, on the right side as well as the left, arise separately from the aorta; and thus Nature reverts to the original condition of perfect symmetry as governing the development of even the vascular skeleton. And not unfrequently, as if to invite us to the inquiry whether a separate origin of the four vessels (subclavian and carotid) from the aorta, or a double innominate condition of the vessels, were the original form with Nature, we find her also presenting this latter arrangement of them. An innominate or common aortic origin may happen for the carotid and subclavian arteries of the left side, as well as the right. Hence, therefore, while experience may arm the judgment with a general rule, such generality should not render us unmindful of the possible exception.

When, as in Plate 9, A, the innominate artery rises to a level with C, the right sterno-clavicular junction, and when at this place it bifurcates, having on its left side, D, the trachea, and on its right side, B, the root of the internal jugular vein, together with a, the vagus nerve, the arterial vessel is said to be of normal character, and holding a normal position relative to adjacent organs. When, as in Plate 10, A, the common carotid, and B, the subclavian artery, rise separately from the aortic arch to a level with Q, the left sterno-clavicular articulation, the vessels having M, the trachea, to their inner side, and C D, the junction of the internal jugular and subclavian veins, to their outer side, with b, the left vagus nerve, between them, then the arterial vessels are accounted as being of normal character, and as holding a normal relative position. Every exception to this condition of A, Plate 9, or to that of A B, Plate 10, is said to be abnormal or peculiar, and merely because the disposition of the vessels, as seen in Plates 9 and 10, is taken to be general or of more frequent occurrence.

Now, though it is not my present purpose to burden this subject of regional anatomy with any lengthy inquiry into the comparative meaning of the facts, why a common innominate trunk should occur on the right of the median line, while separate arterial trunks for the carotid and subclavian arteries should spring from the aorta on the left of this mid-line, thus making a remarkable exception to the rule of symmetry which characterizes all the arterial vessels elsewhere, still I cannot but regard this exceptional fact of asymmetry as in itself expressing a question by no means foreign to the interests of the practical.

In the abstract or general survey of all those peculiarities of length to which the innominate artery, A, Plate 9, is subject, I here lay it down as a proposition, that they occur as graduated phases of the bicleavage of this innominate trunk from the level of A, to the aortic arch, in which latter phasis the aorta gives a separate origin to the carotid and subclavian vessels of the right side as well as the left. On the other hand, I observe that the peculiarities to the normal separate condition of A and B, the carotid and subclavian arteries of Plate 10, display, in the relationary aggregate, a phasial gradation of A and B joining into a common trunk union, in which state we then find the aorta giving origin to a right and left innominate artery. Between these two forms of development—viz., that where the four vessels spring separately from the aortic arch, and that where two innominate or brachio-cephalic arteries arise from the same—may be read all the sum of variation to which these vessels are liable. It is true that there are some states of these vessels which cannot be said to be naturally embraced in the above generalization; but though I doubt not that these might be encompassed in a higher generalization; still, for all practical ends, the lesser general rule is all-sufficient.

In many instances, the innominate artery, A, Plate 9, is of such extraordinary length, that it rises considerably (for an inch, or even more) above the level of C, the sternal end of the clavicle. In other cases, the innominate artery bifurcates soon after it leaves the first part of the aortic arch; and between these extremes as to length, the vessel varies infinitesimally.

The innominate artery lies closer behind the right sterno-clavicular junction than the left carotid or subclavian arteries lie in relation to the left sterno-clavicular articulation; and this difference of depth between the vessel of the right side and those of the left is mainly owing to the form and direction of the aortic arch from which they take origin. The aortic arch ranges, not alone transversely, but also from before backward, and to the left side of the dorsal spine; and consequently, as the innominate artery, A, Plate 9, springs from the first or fore part of the aorta, while the left carotid and subclavian arteries arise from the second and deeper part of its arch, the vessels of both sides rising into the neck perpendicularly from the root in the thorax, will still, in the cervical region, manifest a considerable difference as to antero-posterior depth. The depth of the left subclavian artery, B, Plate 10, from cervical surface, is even greater than that of the left common carotid, A, Plate 10, and this latter, at its root in the aortic arch, is deeper than the innominate artery. Both common carotids, A A, Plates 9 and 10, hold nearly the same antero-posterior depth on either side of the trachea, M, Plate 10, and D, Plate 9. Although the relative depth of the arterial vessels on both sides of the trachea is different, still they are covered by an equal number of identical structures, taking the same order of superposition.

On either side of the episternal cervical pit, which, even in the undissected body of male or female, infant or adult, is always a well-marked surgical feature, may be readily recognised the converging sternal attachments of the sterno-mastoid muscles, L G, Plate 10; and midway between these symmetrical muscular prominences in the neck, but holding a deeper level than them, is situated that part of the trachea which is generally the subject of the operation of tracheotomy. The relative anatomy of the trachea, M, Plate 10, D, Plate 9, at this situation requires therefore to be carefully considered. The trachea is said to incline rather to the right side of the median line; but perhaps this observation would be more true to nature if it were accompanied by the remark, that this seeming inclination to the right side is owing to the fact, that the innominate artery, A, Plate 9, lies obliquely over its fore part, near the sternum. However this may be, it certainly will be the safer step in the operation to regard the median position of the trachea as fixed, than to encroach upon the locality of the carotid vessels; and to make the incision longitudinally and exactly through the median line, while the neck is extended backwards, and the chin made to correspond with the line of incision. And when the operator takes into consideration the situation of the vessel A, Plate 9, and A, Plate 10, at this region of the neck, he will at once own to the necessity of opening the trachea, D, Plate 9, M, Plate 10, at a situation nearer the larynx than the point marked in the figures. The course taken by the common carotid arteries is, in respect to the trachea, divergent from below upwards; and as these vessels will consequently be found to stand wider apart at the level of K, I, Plate 10, than they do at the level of M, Plate 10, so the farther upwards from the sternum we choose the point at which to open the trachea, the less likely are we to endanger the great arterial vessels.

In addition to the fact, that the carotid arteries at an inch above the sternum lie nearer the median line than they do higher up in the neck, it should always be remembered, that the trachea itself is situated much deeper at the point M, Plate 10, D, Plate 9, than it is opposite the points F and K of the same figures. The laryngo-tracheal line is, in the lateral view of the neck, downwards and backwards, and therefore it will be found always at a considerable depth from cervical surface, as it passes behind the first bone of the sternum, midway between both sterno-mastoid muscles.

In the operation of tracheotomy, the cutting instrument divides the following named structures as they lie beneath the common integument: If the incision be made directly upon the median line, the muscles F, sterno-hyoid, and E, sterno-thyroid, Plate 9, are not necessarily divided, as these structures and their fellows hold a somewhat lateral position opposite to each other. Beneath these muscles and above them, thus encasing them, the cervical fascia, f f, Plate 10, is required to be divided, in order to expose the trachea. Beneath f f the cervical fascia, will next be felt the rounded bilobed mass of the thyroid body, lying on the forepart of the trachea; above the thyroid body, the cricoid and some tracheal cartilaginous rings will be felt; and since the thyroid body varies much as to bulk in several individuals of the same and different sexes, as also from a consideration that its substance is traversed by large arterial and venous vessels, it will be therefore preferable to open the trachea above it, than through it or below it.

On the forepart of the tracheal median line, either superficial to, or deeper than, the cervical fascia, the tracheotomist occasionally meets with a chain of lymphatic glands or a plexus of veins, which latter, when divided, will trammel the operation by the copious haemorrhage which all veins at this region of the neck are prone to supply, owing to their direct communication with the main venous trunks of the heart; and not unfrequently the inferior thyroid artery overlies the trachea at the point D, Plate 9, when this thyroid vessel arises directly from the arch of the aorta, between the roots of the innominate and left common carotid, or when it springs from the innominate itself. The inferior thyroid vein, sometimes single and sometimes double, overlies the trachea at the point D, Plate 9, when this vein opens into the left innominate venous trunk, as this latter crosses over the root of the main arteries springing from the aorta.

Laryngotomy is, anatomically considered, a far less dangerous operation than tracheotomy, for the above-named reasons; and the former should always be preferred when particular circumstances do not render the latter operation absolutely necessary. In addition to the fact, that the carotid arteries lie farther apart from each other and from the median place—viz., the crico-thyroid interval, which is the seat of laryngotomy—than they do lower down on either side of the trachea, it should also be noticed that the tracheal tube being more moveable than the larynx, is hence more liable to swerve from the cutting instrument, and implicate the vessels. Tracheotomy on the infant is a far more anxious proceeding than the same operation performed on the adult; because the trachea in the infant’s body lies more closely within the embrace of the carotid arteries, is less in diameter, shorter, and more mobile than in the adult body.

The episternal or interclavicular region is a locality traversed by so many vitally important structures gathered together in a very limited space, that all operations which concern this region require more steady caution and anatomical knowledge than most surgeons are bold enough to test their possession of. The reader will (on comparing Plates 9 and 10) be enabled to take account of those structures which it is necessary to divide in the operation required for ligaturing the innominate artery, A, Plate 9, or either of those main arterial vessels (the right common carotid and subclavian) which spring from it; and he will also observe that, although the same number and kind of structures overlie the carotid and subclavian vessels, A B, of the left side, Plate 10, still, that these vessels themselves, in consequence of their separate condition, will materially influence the like operation in respect to them. An aneurism occurring in the first part of the course of the right subclavian artery, at the locality a, Plate 9, will lie so close to the origin of the right common carotid as to require a ligature to be passed around the innominate common trunk, thus cutting off the flow of blood from both vessels; whereas an aneurism implicating either the left common carotid at the point A, or the left subclavian artery at the point B, does not, of course, require that both vessels should be included in the same ligature. There seems to be, therefore, a greater probability of effectually treating an aneurism of the left brachio-cephalic vessels by ligature than attaches to those of the right side; for if space between collateral branches, and also a lesser caliber of arterial trunk, be advantages, allowing the ligature to hold more firmly, then the vessels of the left side of the root of the neck manifest these advantages more frequently than those of the right, which spring from a common trunk. Whenever, therefore, the “peculiarity” of a separate aortic origin of the right carotid and subclavian arteries occurs, it is to be regarded more as a happy advantage than otherwise.

DESCRIPTION OF PLATES 9 & 10.

PLATE 9.

A. Innominate artery, at its point of bifurcation.

B. Right internal jugular vein, joining the subclavian vein.

C. Sternal end of the right clavicle.

D. Trachea.

E. Right sterno-thyroid muscle, cut.

F. Right sterno-hyoid muscle, cut.

G. Right sterno-mastoid muscle, cut.

a. Right vagus nerve, crossing the subclavian artery.

b. Anterior jugular vein, piercing the cervical fascia to join the subclavian vein.

Plate 9

PLATE 10.

A. Common carotid artery of left side.

B. Left subclavian artery, having b, the vagus nerve, between it and A.

C. Lower end of left internal jugular vein, joining—

D. Left subclavian vein, which lies anterior to d, the scalenus anticus muscle.

E. Anterior jugular vein, coursing beneath sterno-mastoid muscle and over the fascia.

F. Deep cervical fascia, enclosing in its layers f f f, the several muscles.

G. Left sterno-mastoid muscle, cut across, and separated from g g, its sternal and clavicular attachments.

H. Left sterno-hyoid muscle, cut.

I. Left sterno-thyroid muscle, cut.

K. Right sterno-hyoid muscle.

L. Right sterno-mastoid muscle.

M. Trachea.

N. Projection of the thyroid cartilage.

O. Place of division of common carotid.

P. Place where the subclavian artery passes beneath the clavicle.

Q. Sternal end of the left clavicle.

Plate 10

COMMENTARY ON PLATES 11 & 12.

THE SURGICAL DISSECTION OF THE AXILLARY AND BRACHIAL REGIONS, DISPLAYING THE RELATIVE ORDER OF THEIR CONTAINED PARTS.

All surgical regions have only artificial boundaries; and these, as might be expected, do not express the same meaning while viewed from more points than one. These very boundaries themselves, being moveable parts, must accordingly influence the relative position of the structures which they bound, and thus either include within or exclude from the particular region those structures wholly or in part which are said to be proper to it. Of this kind of conventional surgical boundary the moveable clavicle is an example; and the bloodvessels which it overarches manifest consequently neither termination nor origin except artificially from the fixed position which the bone, R, assumes, as in Plate 11, or c*, Plate 12. In this position of the arm in relation to the trunk, the subclavian artery, B, terminates at the point where, properly speaking, it first takes its name; and from this point to the posterior fold of the axilla formed by the latissimus dorsi muscle, O, Plate 11, N, Plate 12, and the anterior fold formed by the great pectoral muscle, K, Plate 11, I, Plate 12, the continuation of the subclavian artery is named axillary. From the posterior fold of the axilla, O P, Plate 11, to the bend of the elbow, the same main vessels take the name of brachial.

When the axillary space is cut into from the forepart through the great pectoral muscle, H K, Plate 11, and beneath this through the lesser pectoral muscle, L I, together with the fascial processes which invest these muscles anteriorly and posteriorly, the main bloodvessels and nerves which traverse this space are displayed, holding in general that relative position which they exhibit in Plate 11. These vessels, with their accompanying nerves, will be seen continued from those of the neck; and thus may be attained in one view a comparative estimate of the cervical and axillary regions, together with their line of union beneath the clavicle, c*, Plate 12, R, Plate 11, which serves to divide them surgically.

In the neck, the subclavian artery, B, Plate 11, is seen to be separated from the subclavian vein, A, by the breadth of the anterior scalenus muscle, D, as the vessels arch over the first rib, F. In this region of the course of the vessels, the brachial plexus of nerves, C, ranges along the outer border of the artery, B, and is separated by the artery from the vein, A, as all three structures pass beneath the clavicle, R, and the subclavius muscle, E. From this latter point the vessels and nerves take the name axillary, and in this axillary region the relative position of the nerves and vessels to each other and to the adjacent organs is somewhat changed. For now in the axillary region the vein, a, is in direct contact with the artery, b, on the forepart and somewhat to the inner side of which the vein lies; while the nerves, D, d, Plate 12, embrace the artery in a mesh or plexus of chords, from which it is often difficult to extricate it, for the purpose of ligaturing, in the dead subject, much less the living. The axillary plexus of nerves well merits the name, for I have not found it in any two bodies assuming a similar order or arrangement. Perhaps the order in which branches spring from the brachial plexus that is most constantly met with is the one represented at D, Plate 12, where we find, on the outer border of B, the axillary artery, a nervous chord, d, giving off a thoracic branch to pass behind H, the lesser pectoral muscle, while the main chord itself, d, soon divides into two branches, one the musculo-cutaneous, e, which pierces G, the coraco-brachialis muscle, and the other which forms one of the roots of the median nerve, h. Following that order of the nerves as they are shown in Plate 12, they may be enumerated from without inwards as follows:—the external or musculo-cutaneous, e; the two roots of the median, h; the ulnar, f; the musculo-spiral, g; the circumflex, i; close to which are seen the origins of the internal cutaneous, the nerve of Wrisberg, some thoracic branches, and posteriorly the subscapular nerve not seen in this view of the parts.

The branches which come off from the axillary artery are very variable both as to number and place of origin, but in general will be found certain branches which answer to the names thoracic, subscapular, and circumflex. These vessels, together with numerous smaller arteries, appear to be confined to no fixed point of origin, and on this account the place of election for passing a ligature around the main axillary artery sufficiently removed from collateral branches must be always doubtful. The subscapular artery, Q, Plate 12, is perhaps of all the other branches that one which manifests the most permanent character; its point of origin being in general opposite the interval between the latissimus and sub-scapular muscles, but I have seen it arise from all parts of the axillary main trunk. If it be required to give, in a history of the arteries, a full account of all the deviations from the so-called normal type to which these lesser branches here and elsewhere are subject, such account can scarcely be said to be called for in this place.

The form of the axillary space is conical, while the arm is abducted from the side, and while the osseous and muscular structures remain entire. The apex of the cone is formed at the root of the neck beneath the clavicle, R, Plate 11, and the subclavious muscle, E, and between the coracoid process, L*, of the scapula and the serratus magnus muscle, as this lies upon the thoracic side; at this apex the subclavian vessels, A B, enter the axillary space. The base of the cone is below, looking towards the arm, and is formed in front by the pectoralis major, K H, and behind by the latissimus dorsi, O, and teres muscles, P, together with a dense thick fascia; at this base the axillary vessels, a b, pass out to the arm, and become the brachial vessels, a*b*. The anterior side of the cone is formed by the great pectoral muscle, H K, Plate 11, and the lesser pectoral, L I. The inner side is formed by the serratus magnus muscle, M, Plate 12, on the side of the thorax; the external side is formed by the scapular and humeral insertion of the subscapular muscle, the humerus and coraco-brachialis muscle; and the posterior side is formed by the latissimus dorsi, the teres and body of the subscapular muscle.

In this axillary region is contained a complicated mass of bloodvessels, nerves, and lymphatic glands, surrounded by a large quantity of loose cellular membrane and adipose tissue. All the arterial branches here found are given off from the axillary artery; and the numerous veins which accompany these branches enter the axillary vein. Nerves from other sources besides those of the axillary plexus traverse the axillary space; such nerves, for example, as those named intercosto-humeral, seen lying on the latissimus tendon, O, Plate 11. The vein named cephalic, S, enters the axillary space at that cellular interval occurring between the clavicular origin of the deltoid muscle, G, and the humeral attachment of the pectoralis major, H, which interval marks the place of incision for tying the axillary artery.

The general course of the main vessels through the axillary space would be indicated with sufficient accuracy by a line drawn from the middle of the clavicle, R R, Plate 11, to the inner border of the biceps muscle, N. In this direction of the axillary vessels, the coracoid process, L*, from which arises the tendon of the pectoralis minor muscle, L, is to be taken as a sure guide to the place of the artery, b, which passes, in general, close to the inner side of this bony process. Even in the undissected body the coracoid process may be felt as a fixed resisting point at that cellular interval between the clavicular attachments of the deltoid and great pectoral muscles. Whatever necessity shall require a ligature to be placed around the axillary in preference to the subclavian artery, must, of course, be determined by the particular case; but certain it is that the main artery, at the place B, a little above the clavicle, will always be found freer and more isolated from its accompanying nerves and vein, and also more easily reached, owing to its comparatively superficial situation, than when this vessel has become axillary. The incision required to be made, in order to reach the axillary artery, b, from the forepart, through the skin, both pectoral muscles, and different layers of fasciae, must be very deep, especially in muscular, well-conditioned bodies; and even when the level of the vessel is gained, it will be found much complicated by its own branches, some of which overlie it, as also by the plexus of nerves, D, Plate 12, which embraces it on all sides, while the large axillary vein, a, Plate 11, nearly conceals it in front. This vein in Plate 11 is drawn somewhat apart from the artery.

Sometimes the axillary artery is double, in consequence of its high division into brachial branches. But as this peculiarity of premature division never takes place so high up as where the vessel, B, Plate 11, overarches the first rib, F, this circumstance should also have some weight with the operator.

When we view the relative position of the subclavian vessels, A B, Plate 11, to the clavicle, R, we can readily understand why a fracture of the middle of this bone through that arch which it forms over the vessels, should interfere with the free circulation of the blood which these vessels supply to the arm. When the clavicle is severed at its middle, the natural arch which the bone forms over the vessels and nerves is lost, and the free moving broken ends of the bone will be acted on in opposing directions by the various muscles attached to its sternal and scapular extremities. The outer fragment follows more freely than the inner piece the action of the muscles; but, most of all, the weight of the unsupported shoulder and arm causes the displacement to which the outer fragment is liable. The subclavius muscle, E, like the pronator quadratus muscle of the forearm, serves rather to further the displacement of the broken ends of the bone than to hold them in situ.

If the head of the humerus be dislocated forwards beneath L, Plate 11, the coracoid attachment of the pectoralis minor muscle, it must press out of their proper place and put tensely upon the stretch the axillary vessels and plexus of nerves. So large and resistent a body as the head of the humerus displaced forwards, and taking the natural position of these vessels and nerves, will accordingly be attended with other symptoms—such as obstructed circulation and pain or partial paralysis, besides those physical signs by which we distinguish the presence of it as a new body in its abnormal situation.

When the main vessels and nerves pass from the axillary space to the inner side of the arm, they become comparatively superficial in this latter situation. The inner border of the biceps muscle is taken as a guide to the place of the brachial artery for the whole extent of its course in the arm. In plate 11, the artery, b*, is seen in company with the median nerve, which lies on its fore part, and with the veins called comites winding round it and passing with it and the nerve beneath the fascia which encases in a fold of itself all three structures in a common sheath. Though the axillary vein is in close contact with the axillary artery and nerves, yet the basilic vein, d*, the most considerable of those vessels which form the axillary vein, is separated from the brachial artery by the fascia. The basilic vein, however, overlies the brachial artery to its inner side, and is most commonly attended by the internal cutaneous nerve, seen lying upon it in Plate 11, as also by that other cutaneous branch of the brachial plexus, named the nerve of Wrisberg. If a longitudinal incision in the course of the brachial artery be made (avoiding the basilic vein) through the integument down to the fascia of the arm, and the latter structure be slit open on the director, the artery will be exposed, having the median nerve lying on its outer side in the upper third of the arm, and passing to its inner side towards the bend of the elbow, as at b*, Plate 12. The superior and inferior profunda arteries, seen springing above and below the point b, Plate 12, are those vessels of most importance which are given off from the brachial artery, but the situation of their origin is very various. The ulnar nerve, f, lies close to the inner side of the main arterial trunk, as this latter leaves the axilla, but from this place to the inner condyle, Q, behind which the ulnar nerve passes into the forearm, the nerve and artery become gradually more and more separated from each other in their descent. The musculo-spiral nerve, g, winds under the brachial artery at the middle of the arm, but as this nerve passes deep between the short and long heads of the triceps muscle, P, and behind the humerus to gain the outer aspect of the limb, a little care will suffice for avoiding the inclusion of it in the ligature.

The brachial artery may be so effectually compressed by the fingers on the tourniquet, against the humerus in any part of its course through the arm, as to stop pulsation at the wrist.

The tourniquet is a less manageable and not more certain compressor of the arterial trunk than is the hand of an intelligent assistant. At every region of the course of an artery where the tourniquet is applicable, a sufficient compression by the hand is also attainable with greater ease to the patient; and the hand may compress the vessel at certain regions where the tourniquet would be of little or no use, or attended with inconvenience, as in the locality of the subclavian artery, passing over the first rib, or the femoral artery, passing over the pubic bone, or the carotid vessels in the neighbourhood of the trachea, as they lie on the fore part of the cervical spinal column.

DESCRIPTION OF PLATES 11 & 12.

PLATE 11.

A. Subclavian vein, crossed by a branch of the brachial plexus given to the subclavius muscle; a, the axillary vein; a *, the basilic vein, having the internal cutaneous nerve lying on it.

B. Subclavian artery, lying on F, the first rib; b, the axillary artery; b *, the brachial artery, accompanied by the median nerve and venae comites.

C. Brachial plexus of nerves; c*, the median nerve.

D. Anterior scalenus muscle.

E. Subclavius muscle.

F F. First rib.

G. Clavicular attachment of the deltoid muscle.

H. Humeral attachment of the great pectoral muscle.

I. A layer of fascia, encasing the lesser pectoral muscle.

K. Thoracic half of the great pectoral muscle.

L. Coracoid attachment of the lesser pectoral muscle.

L*. Coracoid process of the scapula.

M. Coraco-brachialis muscle.

N. Biceps muscle.

O. Tendon of the latissimus dorsi muscle, crossed by the intercosto-humeral nerves.

P. Teres major muscle, on which and O is seen lying Wrisberg’s nerve.

Q. Brachial fascia, investing the triceps muscle. .

R R. Scapular and sternal ends of the clavicle.

S. Cephalic vein, coursing between the deltoid and pectoral muscles, to enter at their cellular interval into the axillary vein beneath E, the subclavius muscle.

Plate 11

PLATE 12.

A. Axillary vein, cut and tied; a, the basilic vein, cut.

B. Axillary artery; b, brachial artery, in the upper part of its course, having h, the median nerve, lying rather to its outer side; b*, the artery in the lower part of its course, with the median nerve to its inner side.

C. Subclavius muscle.

C*. Clavicle.

D. Axillary plexus of nerves, of which d is a branch on the coracoid border of the axillary artery; e, the musculo-cutaneous nerve, piercing the coraco-brachialis muscle; f, the ulnar nerve; g, musculo-spiral nerve; h, the median nerve; i, the circumflex nerve.

E. Humeral part of the great pectoral muscle.

F. Biceps muscle.

G. Coraco-brachialis muscle.

H. Thoracic half of the lesser pectoral muscle.

I. Thoracic half of the greater pectoral muscle.

K. Coracoid attachment of the lesser pectoral muscle.

K*. Coracoid process of the scapula.

L. Lymphatic glands.

M. Serratus magnus muscle.

N. Latissimus dorsi muscle.

O. Teres major muscle.

P. Long head of triceps muscle.

Q. Inner condyle of humerus.

Plate 12

COMMENTARY ON PLATES 13 & 14.

THE SURGICAL FORM OF THE MALE AND FEMALE AXILLAE COMPARED.

Certain characteristic features mark those differences which are to be found in all corresponding regions of both sexes. Though the male and female bodies, in all their regions, are anatomically homologous or similar at basis, yet the constituent and corresponding organs of each are gently diversified by the plus or minus condition, the more or the less, which the development of certain organs exhibits; and this diversity, viewed in the aggregate, constitutes the sexual difference. That diversity which defines the sexual character of beings of the same species, is but a link in that extended chain of differential gradation which marks its progress through the whole animal kingdom. The female breast is a plus glandular organ, situated, pendent, in that very position where, in a male body, the unevolved mamma is still rudimentarily manifested.

The male and female axillae contain the same number and species of organs; and the difference by which the external configuration of both are marked mainly arises from the presence of the enlarged mammary gland, which, in the female, Plate 14, masks the natural outline of the pectoral muscle, E, whose axillary border is overhung by the gland; and thus this region derives its peculiarity of form, contrasted with that of the male subject.

When the dissected axilla is viewed from below, the arm being raised, and extended from the side, its contained parts, laid deeply in their conical recess, are sufficiently exposed, at the same time that the proper boundaries of the axillary cavity are maintained. In this point of view from which the axillary vessels are now seen, their relative position, in respect to the thorax and the arm, are best displayed. The thickness of that fleshy anterior boundary formed by both pectoral muscles, E F, Plate 13, will be marked as considerable; and the depth at which these muscles conceal the vessels, A B, in the front aspect of the thoracico-humeral interval, will prepare the surgeon for the difficulties he is to encounter when proceeding to ligature the axillary artery at the incision made through the anterior or pectoral wall of this axillary space.

The bloodvessels of the axilla follow the motions of the arm; and according to the position assumed by the arm, these vessels describe various curves, and lie more or less removed from the side of the thorax. While the arm hangs close to the side, the axillary space does not (properly speaking) exist; and in this position, the axillary vessels and nerves make a general curve from the clavicle at the point K, Plate 14, to the inner side of the arm, the concavity of the curve being turned towards the thoracic side. But when the arm is abducted from the side, and elevated, the vessels which are destined to supply the limb follow it, and in this position they take, in reality, a serpentine course; the first curve of which is described, in reference to the thorax, from the point K to the head of the humerus; and the next is that bend which the head of the humerus, projecting into the axilla in the elevated position of the member, forces them to make around itself in their passage to the inner side of the arm. The vessels may be readily compressed against the upper third of the humerus by the finger, passed into the axilla, and still more effectually if the arm be raised, as this motion will rotate the tuberous head of the humerus downwards against them.

The vessels and nerves of the axilla are bound together by a fibrous sheath derived from the membrane called costo-coracoid; and the base or humeral outlet of this axillary space, described by the muscles C, K, E, G, Plate 13, is closed by a part of the fascial membrane, g, extended across from the pectoral muscle, E, to the latissimus dorsi tendon, K. In the natural position of the vessels at that region of their course represented in the Plates, the vein A overlies the artery B, and also conceals most of the principal nerves. In order to show some of these nerves, in contact with the artery itself, the axillary vein is drawn a little apart from them.

The axillary space gives lodgment to numerous lymphatic glands, which are either directly suspended from the main artery, or from its principal branches, by smaller branches, destined to supply them. These glands are more numerous in the female axilla, Plate 14, than in the male, Plate 13, and while they seem to be, as it were, indiscriminately scattered here and there through this region, we observe the greater number of them to be gathered together along the axillary side of the great pectoral muscle; at which situation, h, in the diseased condition of the female breast, they will be felt to form hard, nodulated masses, which frequently extend as far up through the axillary space as the root of the neck, involving the glands of this latter region also in the disease.

The contractile motions of the pectoral muscle, E, of the male body, Plate 13, are during life readily distinguishable; and that boundary which it furnishes to the axillary region is well defined; but in the female form, Plate 14, the general contour of the muscle E, while in motion, is concealed by the hemispherical mammary gland, F, which, surrounded by its proper capsule, lies loosely pendent from the fore part of the muscle, to which, in the healthy state of the organ, it is connected only by free-moving bonds of lax cellular membrane. The motions of the shoulder upon the trunk do not influence the position of the female mammary gland, for the pectoral muscle acts freely beneath it; but when a scirrhus or other malignant growth involves the mammary organ, and this latter contracts, by the morbid mass, a close adhesion to the muscle, then these motions are performed with pain and difficulty.

When it is required to excise the diseased female breast, (supposing the disease to be confined to the structure of the gland itself,) the operation may be performed confidently and without difficulty, in so far as the seat of operation does not involve the immediate presence of any important nerves or bloodvessels. But when the disease has extended to the axillary glands, the extirpation of these (as they lie in such close proximity to the great axillary vessels and their principal branches) requires cautious dissection. It has more than once happened to eminent surgeons, that in searching for and dissecting out these diseased axillary glands, H, h, Plate 14, the main artery has been wounded.

As the coracoid process points to the situation of the artery in the axilla, so the coraco-brachialis muscle, C, marks the exact locality of the vessel as it emerges from this region; the artery ranges along the inner margin of both the process and the muscle, which latter, in fleshy bodies, sometimes overhangs and conceals it. When the vessel has passed the insertion of the coraco-brachialis, it becomes situated at the inner side of the biceps, which also partly overlaps it, as it now lies on the forepart of the brachialis anticus. As the general course of the artery, from where it leaves the axilla to the bend of the elbow, is one of winding from the inner side to the forepart of the limb, so should compression of the vessel, when necessary, be directed in reference to the bone accordingly—viz., in the upper or axillary region of the arm, from within outwards, and in the lower part of the arm, from before backwards.

All incised, lacerated, or contused wounds of the arm and shoulder, happening by pike, bayonet, sabre, bullet, mace, or arrow, on the outer aspect of the limb, are (provided the weapon has not broken the bones) less likely to implicate the great arteries, veins, and nerves. These instruments encountering the inner or axillary aspect of the member, will of course be more likely to involve the vessels and nerves in the wound. In severe compound fractures of the humerus occurring from force applied at the external side of the limb, the brachial vessels and nerves have been occasionally lacerated by the sharp jagged ends of the broken bone,—a circumstance which calls for immediate amputation of the member.

The axilla becomes very frequently the seat of morbid growths, which, when they happen to be situated beneath the dense axillary fascia, and have attained to a large size, will press upon the vessels and nerves of this region, and cause very great inconvenience. Adipose and other kind of tumours occurring in the axilla beneath the fascia, and in close contact with the main vessels, have been known to obstruct these vessels to such a degree, as to require the collateral or anastomatic circulation to be set up for the support; of the limb. When abscesses take place in the axilla, beneath the fascia, it is this structure which will prevent the matter from pointing; and it is required, therefore, to lay this fascia freely open by a timely incision. The accompanying Plates will indicate the proper direction in which such incision should be made, so as to avoid the vessels A, B. When the limb is abducted from the side, the main vessels and nerves take their position parallel with the axis of the arm. The axillary vessels and nerves being thus liable to pressure from the presence of large tumours happening in their neighbourhood, will suggest to the practitioner the necessity for fashioning of a proper form and size all apparatus, which in fracture or dislocation of the shoulder-bones shall be required to bear forcibly against the axillary region. While we know that the locality of the main vessels and nerves is that very situation upon which a pad or fulcrum presses, when placed in the axilla for securing the reduction of fractures of the clavicle, the neck of the humerus, or scapula, so should this member of the fracture apparatus be adapted, as well to obviate this pressure upon these structures, as to give the needful support to the limb in reference to the clavicle, &c. The habitual use, for weeks or more, of a hard, resisting fulcrum in the axilla, must act in some degree like the pad of a tourniquet, arresting the flow of a vigorous circulation, which is so essential to the speedy union of all lesions of bones. And it should never be lost sight of, that all grievously coercive apparatus, which incommode the suffering patient, under treatment, are those very instruments which impede the curative process of Nature herself.

The anatomical mechanism of the human body, considered as a whole, or divisible into regions, forms a study so closely bearing upon practice, that the surgeon, if he be not also a mechanician, and fully capable of making his anatomical knowledge suit with the common principles of mechanics, while devising methods for furthering the efforts, of Nature curatively, may be said to have studied anatomy to little or no purpose. The shoulder apparatus, when studied through the principle of mechanics, derives an interest of practical import which all the laboured description of the schools could never supply to it, except when illustrating this principle.

The disposal of the muscular around the osseous elements of the shoulder apparatus, forms a study for the surgeon as well in the abnormal condition of these parts, as in their normal arrangement; for in practice he discovers that that very mechanical principle upon which both orders of structures (the osseous and muscular) are grouped together for normal articular action, becomes, when the parts are deranged by fracture or, other accident, the chief cause whereby rearrangement is prevented, and the process of reunion obstructed. When a fracture happens in the shaft of the humerus, above or below the insertions of the pectoral and latissimus dorsi muscles, these are the very agents which when the bone possessed its integrity rendered it functionally fitting, and which, now that the bone is severed, produce the displacement of the lower fragment from the upper one. To counteract this source of derangement, the surgeon becomes the mechanician, and now, for the first time, he recognises the necessity of the study of topographical anatomy.

When a bone is fractured, or dislocated to a false position and retained there by the muscular force, the surgeon counteracts this force upon mechanical principle; but while he puts this principle in operation, he also acknowledges to the paramount necessity of ministering to the ease of Nature as much as shall be consistent with the effectual use of the remedial agent; and in the present state of knowledge, it is owned, that that apparatus is most efficient which simply serves both objects, the one no less than the other. And, assuming this to be the principle which should always guide us in our treatment of fractures and dislocations, I shall not hesitate to say, that the pad acting as a fulcrum in the axilla, or the perineal band bearing as a counterextending force upon the groin (the suffering body of the patient being, in both instances, subjected for weeks together to the grievous pressure and irritation of these members of the apparatus), do not serve both objects, and only one incompletely; I say incompletely, for out of every six fractures of either clavicle or thigh-bone, I believe that, as the result of our treatment by the present forms of mechanical contrivances, there would not be found three cases of coaptation of the broken ends of the bone so complete as to do credit to the surgeon. The most pliant and portable of all forms of apparatus which constitute the hospital armamentaria, is the judgment; and this cannot give its approval to any plan of instrument which takes effect only at the expense of the patient.

DESCRIPTION OF PLATES 13 & 14.

PLATE 13.

A. Axillary vein, drawn apart from the artery, to show the nerves lying between both vessels. On the bicipital border of the vein is seen the internal cutaneous nerve; on the tricipital border is the nerve of Wrisberg, communicating with some of the intercosto-humeral nerves; a, the common trunk of the venae comites, entering the axillary vein.

B. Axillary artery, crossed by one root of the median nerve; b, basilic vein, forming, with a, the axillary vein, A.

C. Coraco-brachialis muscle.

D. Coracoid head of the biceps muscle.

E. Pectoralis major muscle.

F. Pectoralis minor muscle.

G. Serratus magnus muscle, covered by g, the axillary fascia, and perforated, at regular intervals, by the nervous branches called intercosto-humeral.

H. Conglobate gland, crossed by the nerve called “external respiratory” of Bell, distributed to the serratus magnus muscle. This nerve descends from the cervical plexus.

I. Subscapular artery.

K. Tendon of latissimus dorsi muscle.

L. Teres major muscle.

Plate 13

PLATE 14.

A. Axillary vein.

B. Axillary artery.

C. Coraco-brachialis muscle.

D. Short head of the biceps muscle.

E. Pectoralis major muscle.

F. Mammary gland, seen in section.

G. Serratus magnus muscle.

H. Lymphatic gland; h h, other glands of the lymphatic class.

I. Subscapular artery, crossed by the intercosto-humeral nerves and descending parallel to the external respiratory nerve. Beneath the artery is seen a subscapular branch of the brachial plexus, given to the latissimus dorsi muscle.

K. Locality of the subclavian artery.

L. Locality of the brachial artery at the bend of the elbow.

Plate 14

COMMENTARY ON PLATES 15 & 16.

THE SURGICAL DISSECTION OF THE BEND OF THE ELBOW AND THE FOREARM, SHOWING THE RELATIVE POSITION OF THE ARTERIES, VEINS, NERVES, &c.

The farther the surgical region happens to be removed from the centre of the body, the less likely is it that all accidents or operations which involve such regions will concern the life immediately. The limbs undergo all kinds of mutilation, both by accident and intention, and yet the patient survives; but when the like happens at any region of the trunk of the body, the life will be directly and seriously threatened. It seems, therefore, that in the same degree as the living principle diverges from the body’s centre into the outstanding members, in that degree is the life weakened in intensity; and just as, according to physical laws, the ray of light becomes less and less intense by the square of the distance from the central source, so the vital ray, or vis, loses momentum in the same ratio as it diverges from the common central line to the periphery.

The relative anatomy of every surgical region becomes a study of more or less interest to the surgeon, according to the degree of importance attaching to the organs contained, or according to the frequency of such accidents as are liable to occur in each. The bend of the elbow is a region of anatomical importance, owing to the fact of its giving passage to C, Plate 15, the main artery of the limb, and also because in it are located the veins D, B, E, F, which are frequently the subject of operation. The anatomy of this region becomes, therefore, important; forasmuch as the operation which is intended to concern the veins alone, may also, by accident, include the main arterial vessel which they overlie. The nerves, which are seen to accompany the veins superficially, as well as that which accompanies the more deeply-situated artery, are, for the same reason, required to be known.

The course of the brachial artery along the inner border of the biceps muscle is comparatively superficial, from the point where it leaves the axilla to the bend of the elbow. In the whole of this course it is covered by the fascia of the arm, which serves to isolate it from the superficial basilic vein, B, and the internal cutaneous nerve, both of which nevertheless overlie the artery. The median nerve, d, Plate 15, accompanies the artery in its proper sheath, which is a duplication of the common fascia; and in this sheath are also situated the venae comites, making frequent loops around the artery. The median nerve itself, D, Plate 16, takes a direct course down the arm; and the different relative positions which this nerve holds in reference to the artery, C, at the upper end, the middle, and the lower end of the arm, occur mainly in consequence of the undulating character of the vessel itself.

When it is required to ligature the artery in the middle of the arm, the median nerve will be found, in general, at its outer side, between it and the biceps; but as the course of the artery is from the inner side of the biceps to the middle of the bend of the elbow, so we find it passing under the nerve to gain this locality, C, Plate 16, where the median nerve, D, then becomes situated at the inner side of the vessel. The median nerve, thus found to be differently situated in reference to the brachial artery, at the upper, the middle, and the lower part of the arm, is (with these facts always held in memory) taken as the guide to that vessel. An incision made of sufficient length (an inch and a half, more or less) over the course of the artery, and to the outer side of the basilic vein, B, Plate 16, will divide the skin, subcutaneous adipose membrane, which varies much in thickness in several individuals, and will next expose the common fascial envelope of the arm. When this fascia is opened, by dividing it on the director, the artery becomes exposed; the median nerve is then to be separated from the side of the vessel by the probe or director, and, with the precaution of not including the venal comites, the ligature may now be passed around the vessel. In the lower third of the arm it is not likely that the operator will encounter the ulnar nerve, and mistake it for the median, since the former, d, Plate 16, is considerably removed from the vessel. If the incision be made precisely in the usual course of the brachial artery, the ulnar nerve will not show itself. It will be well, however, to bear in mind the possible occurrence of some of those anomalies to that normal relative position of the artery, the median, and the ulnar nerve, which the accompanying Plates represent.

The median nerve, D, Plate 16, is sometimes found to lie beneath the artery in the middle and lower third of the arm. At other times it is found far removed to the inner side of the usual position of the vessel, and lying in close contact with the ulnar nerve, d. Or the brachial artery may take this latter position, while the median nerve stands alone at the position of D, Plate 16. Or both the main artery and the median nerve may course much to the inner side of the biceps muscle, A, Plate 16, while in the usual situation of the nerve and vessel there is only to be found a small arterial branch (the radial), which springs from the brachial, high up in the arm. Or the nerve and vessel may be lying concealed beneath a slip of the brachialis anticus muscle, E, Plate 16, in which case no appearance of them will be at all manifested through the usual place of incision made for the ligature of the brachial vessel. Or, lastly, there may be found more arteries than the single main brachial appearing at this place in the arm, and such condition of a plurality of vessels occurs in consequence of a high division of the brachial artery. Each of these variations from the normal type is more or less frequent; and though it certainly is of practical import to bear them in mind, still, as we never can foretell their occurrence by a superficial examination of the limb, or pronounce them to be present till we actually encounter them in operation, it is only when we find them that we commence to reason upon the facts; but even at this crisis the knowledge of their anatomy may prevent a confusion of ideas.

That generalization of the facts of such anomalies as are liable to occur to the normal character of the brachial artery, represented in Plates 15 and 16, which appears to me as being most inclusive of all their various conditions, is this—viz., that the point of division into radial, ulnar, and interosseous, which F, Plate 16, usually marks, may take place at any part of the member between the bend of the elbow and the coracoid process in the axillary space.

At the bend of the elbow, the brachial artery usually occupies the middle point between e, the inner condyle of the humerus and the external margin of the supinator radii longus muscle, G. The structures which overlie the arterial vessel, C, Plate 16, at this locality, numbering them from its own depth to the cutaneous surface, are these— viz., some adipose cellular membrane envelopes the vessel, as it lies on E, the brachialis anticus muscle, and between the two accompanying veins; at the inner side of the artery, but separated from it by a small interval occupied by one of the veins, is situated the median nerve d, Plate 15. Above all three structures is stretched that dense fibrous band of the fascia, H, Plate 16, which becomes incorporated with the common fascial covering of the forearm. Over this fascial process lies the median basilic vein, F B, Plate 15, accompanying which are seen some branches of the internal cutaneous nerve. The subcutaneous adipose tissue and common integument cover these latter. If it be required to ligature the artery at this locality, an incision two inches and a half in length, made along the course of the vessel, and avoiding the superficial veins, will expose the fascia; and this being next divided on the director, the artery will be exposed resting on the brachialis anticus, and between the biceps tendon and pronator teres muscle. As this latter muscle differs in width in several individuals, sometimes lying in close contact with the artery, and at other times leaving a considerable interval between the vessel and itself, its outer margin is not, therefore, to be taken as a sure guide to the artery. The inner border of the biceps indicates much more generally the situation of the vessel.

The bend of the elbow being that locality where the operation of phlebotomy is generally performed, it is therefore required to take exact account of the structures which occupy this region, and more especially the relation which the superficial veins hold to the deeper seated artery. In Plate 15, the artery, C, is shown in its situation beneath the fascial aponeurosis, which comes off from the tendon of the biceps, a portion of which has been cut away; and the venous vessel, F B, which usually occupies the track of the artery, is pushed a little to the inner side. While opening any part of the vessel, F B, which overlies the artery, it is necessary to proceed with caution, as well because of the fact that between the artery, C, and the vein, F B, the fascia alone intervenes, as also because the ulnar artery is given off rather frequently from the main vessel at this situation, and passes superficial to the fascia and flexors of the forearm, to gain its usual position at K, Plate 15. I have met with a well marked example of this occurrence in the living subject.

The cephalic vein, D, is accompanied by the external cutaneous nerve, which branches over the fascia on the outer border of the forearm. The basilic vein, B, is accompanied by the internal cutaneous nerve, which branches in a similar way over the fascia of the inner and fore part of the forearm. The numerous branches of both these nerves interlace with the superficial veins, and are liable to be cut when these veins are being punctured. Though the median basilic, F, and the basilic vein, B, are those generally chosen in the performance of the operation of bleeding, it will be seen, in Plate 15, that their contiguity to the artery necessarily demands more care and precision in that operation executed upon them, than if D, the cephalic vein, far removed as it is from the course of the artery, were the seat of phlebotomy.

As it is required, in order to distend the superficial veins, D, B, F, that a band should be passed around the limb at some locality between them and the heart, so that they may yield a free flow of blood on puncture, a moderate pressure will be all that is needful for that end. It is a fact worthy of notice, that the excessive pressure of the ligaturing band around the limb at A B, Plate 15, will produce the same effect upon the veins near F, as if the pressure were defective, for in the former case the ligature will obstruct the flow of blood through the artery; and the vein, F, will hence be undistended by the recurrent blood, just as when, in the latter case, the ligature, making too feeble a pressure on the vein, B, will not obstruct its current in that degree necessary to distend the vessel, F.

Whichever be the vein chosen for phlebotomy at the bend of the elbow, it will be seen, from an examination of Plates 15 and 16, that the opening may be made with most advantage according to the longitudinal axis of the vessel; for the vessel while being cut open in this direction, is less likely to swerve from the point of the lancet than if it were to be incised across, which latter mode is also far more liable to implicate the artery. Besides, as the nerves course along the veins from above downwards—making, with each other, and with the vessels, but very acute angles—all incisions made longitudinally in these vessels, will not be so likely to divide any of these nerves as when the instrument is directed to cut crossways.

The brachial artery usually divides, at the bend of the elbow, into the radial, the ulnar, and the interosseous branches. The point F, Plate 16, is the common place of division, and this will be seen in the Plate to be somewhat below the level of the inner condyle, e. From that place, where the radial and ulnar arteries spring, these vessels traverse the forearm, in general under cover of the muscles and fascia, but occasionally superficial to both these structures. The radial artery, F N, Plate 16, takes a comparatively superficial course along the radial border of the forearm, and is accompanied, for the upper two-thirds of its length, by the radial branch of the musculo-spiral nerve, seen in Plate 16, at the outer side of the vessel. The supinator radii longus muscle in general overlaps, with its inner border, both the radial artery and nerve. At the situation of the radial pulse, I, Plate 15, the artery is not accompanied by the nerve, for this latter will be seen, in plate 16, to pass outward, under the tendon of the supinator muscle, to the integuments.

The ulnar artery, whose origin is seen near F, Plate 16, passes deeply beneath the superficial flexor muscles, L M K, and the pronator teres, I, and first emerges from under cover of these at the point O, from which point to S, Plate 16, the artery may be felt, in the living body, obscurely beating as the ulnar pulse. On the inner border of the ulnar artery, and in close connexion with it, the ulnar nerve may be seen looped round by small branches of the vessel.

The radial and ulnar arteries may be exposed and ligatured in any part of their course; but of the two, the radial vessel can be reached with greater facility, owing to its comparatively superficial situation. The inner border of the supinator muscle, G, Plate 16, is the guide to the radial artery; and the outer margin of the flexor carpi ulnaris muscle, K, Plate 16, indicates the locality of the ulnar artery. Both arteries, I, K, Plate 15, at the wrist, lie beneath the fascia. If either of these vessels require a ligature in this region of the arm, the operation may be performed with little trouble, as a simple incision over the track of the vessels, through the skin and the fascia, will readily expose each.

Whenever circumstances may call for placing a ligature on the ulnar artery, as it lies between the superficial and deep flexor muscles, in the region of I L M, Plate 16, the course of the vessel may be indicated by a line drawn from a central point of the forearm, an inch or so below the level of the inner condyle—viz., the point F, and carried to the pisiform bone, T. The line of incision will divide obliquely the superficial flexors; and, on a full exposure of the vessel in this situation, the median nerve will be seen to cross the artery at an acute angle, in order to gain the mid-place in the wrist at Q. The ulnar nerve, d, Plate 16, passing behind the inner condyle, e, does not come into connexion with the ulnar artery until both arrive at the place O. It will, however, be considered an awkward proceeding to subject to transverse section so large a mass of muscles as the superficial flexors of the forearm, when the vessel may be more readily reached elsewhere, and perhaps with equal advantage as to the locality of the ligature.

When either the radial or ulnar arteries happen to be completely divided in a wound, both ends of the vessel will bleed alike, in consequence of the free anastomosis of both arteries in the hand.

DESCRIPTION OF PLATES 15 & 16.

PLATE 15.

A. Fascia covering the biceps muscle.

B. Basilic vein, with the internal cutaneous nerve.

C. Brachial artery, with the venae comites.

D. Cephalic vein, with the external cutaneous nerve; d, the median nerve.

E. A communicating vein, joining the venae comites.

F. Median basilic vein.

G. Lymphatic gland.

H. Radial artery at its middle.

I. Radial artery of the pulse.

K. Ulnar artery, with ulnar nerve.

L. Palmaris brevis muscle.

Plate 15

PLATE 16.

A. Biceps muscle.

B. Basilic vein, cut.

C. Brachial artery.

D. Median nerve; d, the ulnar nerve.

E. Brachialis anticus muscle; e, the internal condyle.

F. Origin of radial artery.

G. Supinator radii longus muscle.

H. Aponeurosis of the tendon of the biceps muscle.

I. Pronator teres muscle.

K. Flexor carpi ulnaris muscle.

L. Flexor carpi radialis muscle.

M. Palmaris longus muscle.

N. Radial artery, at its middle, with the radial nerve on its outer side.

O. Flexor digitorum sublimis.

P. Flexor pollicis longus.

Q. Median nerve.

R. Lower end of radial artery.

S. Lower end of ulnar artery, in company with the ulnar nerve.

T. Pisiform bone.

U. Extensor metacarpi pollicis.

Plate 16

COMMENTARY ON PLATES 17, 18, & 19.

THE SURGICAL DISSECTION OF THE WRIST AND HAND.

A member of such vast importance as the human hand necessarily claims a high place in regard to surgery. The hand is typical of the mind. It is the material symbol of the immaterial spirit, It is the prime agent of the will; and it is that instrument by which the human intellect manifests its presence in creation. The human hand has a language of its own. While the tongue demonstrates the thought through the word, the hand realizes and renders visible the thought through the work. This organ, therefore, by whose fitness of form the mind declares its own entity in nature, by the invention and creation of the thing, which is, as it were, the mind’s autograph, claims a high interest in surgical anatomy; and accordingly the surgeon lays it down as a rule, strictly to be observed, that when this beautiful and valuable member happens to be seriously mutilated, in any of those various accidents to which it is exposed, the prime consideration should be, not as to the fact of how much of its quantity or parts it can be deprived in operation, but rather as to how little of its quantity should it be deprived, since no mechanical ingenuity can fashion an apparatus, capable of supplying the loss of a finger, or even of one of its joints.

The main blood vessels and nerves of the arm traverse the front aspect of the wrist, and are distributed chiefly to supply the palmar surface of the hand, since in the palm are to be found a greater variety and number of structures than are met with on the back of the hand. The radial artery, A, Plate 17, occupies (as its name indicates) the radial border of the forepart of the wrist, and the ulnar artery, C, Plate 17, occupies the ulnar border; both vessels in this region of their course lie parallel to each other; both are comparatively superficial, but of the two, the radial artery is the more superficial and isolated, and thereby occasions the radial pulse. The anatomical situation of the radial artery accounts for the fact, why the pulsation of this vessel is more easily felt than that of the ulnar artery.

The radial vessel, A, Plate 17, at the wrist, is not accompanied by the radial nerve; for this nerve, C, Plate 19, passes from the side of the artery, at a position, C, Plate 19, varying from one to two or more inches above the wrist, to gain the dorsal aspect of the hand. The ulnar artery, C, Plate 17, is attended by the ulnar nerve, D, in the wrist, and both these pass in company to the palm. The ulnar nerve, D E, lies on the ulnar border of the artery, and both are in general to be found ranging along the radial side of the tendon of the flexor carpi ulnaris muscle, T, and the pisiform bone, G. The situation of the radial artery is midway between the flexor carpi radialis tendon, I, and the outer border of the radius. The deep veins, called comites, lie in close connexion with the radial and ulnar arteries. When it is required to lay bare the radial or ulnar artery, at the wrist, it will be sufficient for that object to make a simple longitudinal incision (an inch or two in length) over the course of the vessel A or C, Plate 17, through the integument, and this incision will expose the fascia, which forms a common investment for all the structures at this region. When this fascia has been cautiously slit open on the director, the vessels will come into view. The ulnar artery, however, lies somewhat concealed between the adjacent muscles, and in order to bring this vessel fully into view, it will be necessary to draw aside the tendon of the flexor ulnaris muscle, T.

The radial artery, A, Plate 18, passes external to the radial border of the wrist, beneath the extensor tendons, B, of the thumb; and after winding round the head of the metacarpal bone of the thumb, as seen at E, Plate 19, forms the deep palmar arch E, Plate 18. This deep palmar arch lies close upon the forepart of the carpo-metacarpal joints; it sends off branches to supply the deeply situated muscles, and other structures of the palm; and from it are also derived other branches, which pierce the interosseal spaces, and appear on the back of the hand, Plate 19. The deep palmar arch, E, Plate 18, inosculates with a branch of the ulnar artery, I, Plate 18, whilst its dorsal interosseal branches, Plate 19, communicate freely with the dorsal carpal arch, which is formed by a branch of the radial artery E, Plate 19, and the terminal branch of the posterior interosseous vessel.

The ulnar artery, C, Plate 17, holds a direct and superficial course, from the ulnar border of the forearm through the wrist; and still remains superficial in the palm, where it forms the superficial palmar arch, F. From this arch arise three or four branches of considerable size, which are destined to supply the fingers. A little above the interdigital clefts, each of these digital arteries divides into two branches, which pass along the adjacent sides of two fingers—a mode of distribution which also characterises the digital branches of the median, b b, and ulnar nerves, e e. The superficial palmar arch of the ulnar vessel anastomoses with the deep arch of the radial vessel. The principal points of communication are, first, by the branch, (ramus profundus,) I, Plate 18, which passes between the muscles of the little finger to join the deep arch beneath the long flexor tendons. 2nd, by the branch (superficialis volae) which springs from the radial artery, A, Plate 17, and crosses the muscles of the ball of the thumb, to join the terminal branch of the superficial arch, F, Plate 17. 3rd, by another terminal branch of the superficial arch, which joins the arteries of the thumb, derived from the radial vessel, as seen at e, Plate 18.

The frequent anastomosis thus seen to take place between the branches of the radial, the ulnar, and the interosseous arteries in the hand, should be carefully borne in mind by the surgeon. The continuity of the three vessels by anastomosis, renders it very difficult to arrest a haemorrhage occasioned by a wound of either of them. It will be at once seen, that when a haemorrhage takes place from any of these larger vessels of the hand, the bleeding will not be commanded by the application of a ligature to either the radial, the ulnar, or the interosseous arteries in the forearm; and for this plain reason, viz., that though in the arm these arteries are separate, in the hand their communication renders them as one.

If a haemorrhage therefore take place from either of the palmar vessels, it will not be sufficient to place a ligature around the radial or the ulnar artery singly, for if F, Plate 17, bleeds, and in order to arrest that bleeding we tie the vessel C, Plate 17, still the vessel F will continue to bleed, in consequence of its communication with the vessel E, Plate 18, by the branch 1, Plate 18, and other branches above mentioned. If E, Plate 18, bleeds, a ligature applied to the vessel A, Plate 18, will not stop the flow of blood, because of the fact that E anastomoses with G, by the branch I and other branches, as seen in Plates 17 and 19.

Any considerable haemorrhage, therefore, which may be caused by a wound of the superficial or deep palmar arches, or their branches, and which we are unable to arrest by compression, applied directly to the patent orifices of the vessel, will in general require that a ligature be applied to both the radial and ulnar arteries at the wrist; and it occasionally happens that even this proceeding will not stop the flow of blood, for the interosseous arteries, which also communicate with the vessels of the hand, may still maintain the current of circulation through them. These interosseous arteries being branches of the ulnar artery, and being given off from the vessel at the bend of the elbow, if the bleeding be still kept up from the vessel wounded in the hand, after the ligature of the ulnar and radial arteries is accomplished, are in all probability the channels of communication, and in this case the brachial artery must be tied. A consideration of the above mentioned facts, proper to the normal distribution of the vessels of the upper extremity, will explain to the practitioner the cause of the difficulty which occasionally presents itself, as to the arrest of haemorrhage from the vessels of the hand. In addition to these facts he will do well to remember some other arrangements of these vessels, which are liable to occur; and upon these I shall offer a few observations.

While I view the normal disposition of the arteries of the arm as a whole, (and this view of the whole great fact is no doubt necessary, if we would take within the span and compass of the reason, all the lesser facts of which the whole is inclusive,) I find that as one main vessel (the brachial) divides into three lesser branches, (the ulnar, radial and interosseous,) so, therefore, when either of these three supplies the haemorrhage, and any difficulty arises preventing our having access at once to the open orifices of the wounded vessel, we can command the flow of blood by applying a ligature to the main trunk—the brachial. If this measure fail to command the bleeding, then we may conclude that the wounded vessel (whichever it happen to be, whether the radial, the ulnar, or the interosseous) arises from the brachial artery, higher up in the arm than that place whereat we applied the ligature. To this variety as to the place of origin, the ulnar, radial, and interosseous arteries are individually liable.

Again, as the single brachial artery divides into the three arteries of the forearm, and as these latter again unite into what may (practically speaking) be termed a single vessel in the hand, in consequence of their anastomosis, so it is obvious that in order to command a bleeding from any of the palmar arteries, we should apply a ligature upon each of the vessels of the forearm, or upon the single main vessel in the arm. When the former proceeding fails, we have recourse to the latter, and when this latter fails (for fail it will, sometimes,) we then reasonably arrive at the conclusion that some one of the three vessels of the forearm, springs higher up than the place of the ligature on the main brachial vessel.

But however varied as to the normal locality of their origin, at the bend of the elbow, these vessels of the forearm may at times manifest themselves, still one point is quite fixed and certain, viz., that they communicate with each other in the hand. Hence, therefore, it becomes evident, that in order to command, at once and effectually, a bleeding, either from the palmar arteries, or those of the forearm, we attain to a more sure and successful result, the nearer we approach the fountain-head and place a ligature on it—the brachial artery. It is true that to stop the circulation through the main vessel of the limb, is always attended with danger, and that such a proceeding is never to be adopted but as the lesser one of two great hazards. It is also true that to tie the main brachial artery for a haemorrhage of anyone of its terminal branches, may be doing too much, while a milder course may serve; or else that even our tying the brachial may not suffice, owing to a high distribution of the vessels of the arm, in the axilla, above the place of the ligature. Thus doubt as to the safest measure, viz., that which is sufficient and no more, enveils the proper place whereat to apply a ligature on the principal vessel; but whatever be the doubt as to this particular, there can be none attending the following rule of conduct, viz., that in all cases of haemorrhage, caused by wounds of the vessels of the upper limb, we should, if at all practicable, endeavour to stop the flow of blood from the divided vessels in the wound itself, by ligature or otherwise; and both ends of the divided vessel require to be tied. Whenever this may be done, we need not trouble ourselves concerning the anomaly in vascular distribution.

The superficial palmar arch, F, Plate 17, lies beneath the dense palmar fascia; and whenever matter happens to be pent up by this fascia, and it is necessary that an opening be made for its exit, the incision should be conducted at a distance from the locality of the vessel. When matter forms beneath the palmar fascia, it is liable, owing to the unyielding nature of this fibrous structure, to burrow upwards into the forearm, beneath the annular ligament D, Plates 17 and 18. All deep incisions made in the median line of the forepart of the wrist are liable to wound the median nerve B, Plate 17. When the thumb, together with its metacarpal bone, is being amputated, the radial artery E, Plate 19, which winds round near the head of that bone, may be wounded. It is possible, by careful dissection, to perform this operation without dividing the radial vessel.

DESCRIPTION OF PLATES 17, 18, & 19.

PLATE 17.

A. Radial artery.

B. Median nerve; b b b b, its branches to the thumb and fingers.

C. Ulnar artery, forming F, the superficial palmar arch.

D. Ulnar nerve; E e e, its continuation branching to the little and ring fingers, &c.

G. Pisiform bone.

H. Abductor muscle of the little finger.

I. Tendon of flexor carpi radialis muscle.

K. Opponens pollicis muscle.

L. Flexor brevis muscle of the little finger.

M. Flexor brevis pollicis muscle.

N. Abductor pollicis muscle.

OOOO. Lumbricales muscles.

P P P P. Tendons of the flexor digitorum sublimis muscle.

Q. Tendon of the flexor longus pollicis muscle.

R. Tendon of extensor metacarpi pollicis.

S. Tendons of extensor digitorum sublimis; P P P, their digital prolongations.

T. Tendon of flexor carpi ulnaris.

U. Union of the digital arteries at the tip of the finger.

Plate 17

PLATE 18.

A. Radial artery.

B. Tendons of the extensors of the thumb.

C. Tendon of extensor carpi radialis.

D. Annular ligament.

E. Deep palmar arch, formed by radial artery giving off e, the artery of the thumb.

F. Pisiform bone.

G. Ulnar artery, giving off the branch I to join the deep palmar arch E of the radial artery.

H. Ulnar nerve; h, superficial branches given to the fingers. Its deep palmar branch is seen lying on the interosseous muscles, M M.

K. Abductor minimi digiti.

L. Flexor brevis minimi digiti.

M. Palmar interosseal muscles.

N. Tendons of flexor digitorum sublimis and profundus, and the lumbricales muscles cut and turned down.

O. Tendon of flexor pollicis longus.

P. Carpal end of the metacarpal bone of the thumb.

Plate 18

PLATE 19. AAA. Tendons of extensor digitorum communis; A*, tendon overlying that of the indicator muscle.

B. Dorsal part of the annular ligament.

C. End of the radial nerve distributed over the back of the hand, to two of the fingers and the thumb.

D. Dorsal branch of the ulnar nerve supplying the back of the hand and the three outer fingers.

E. Radial artery turning round the carpal end of the metacarpal bone of the thumb.

F. Tendon of extensor carpi radialis brevis.

G. Tendon of extensor carpi radialis longus.

H. Tendon of third extensor of the thumb.

I. Tendon of second extensor of the thumb.

K. Tendon of extensor minimi digiti joining a tendon of extensor communis.

Plate 19

COMMENTARY ON PLATES 20 & 21.

THE RELATIVE POSITION OF THE CRANIAL, NASAL, ORAL, AND PHARYNGEAL CAVITIES, &c.

On making a section (vertically through the median line) of the cranio-facial and cervico-hyoid apparatus, the relation which these structures bear to each other in the osseous skeleton reminds me strongly of the great fact enunciated by the philosophical anatomists, that the facial apparatus manifests in reference to the cranial structures the same general relations which the hyoid apparatus bears to the cervical vertebrae, and that these relations are similar to those which the thoracic apparatus bears to the dorsal vertebrae. To this anatomical fact I shall not make any further allusions, except in so far as the acknowledgment of it shall serve to illustrate some points of surgical import.

The cranial chamber, A A H, Plate 20, is continuous with the spinal canal C. The osseous envelope of the brain, called calvarium, Z B, holds serial order with the cervical spinous processes, E I, and these with the dorsal spinous processes. The dura-matral lining membrane, A A A*, of the cranial chamber is continuous with the lining membrane, C, of the spinal canal. The brain is continuous with the spinal cord. The intervertebral foramina of the cervical spine are manifesting serial order with the cranial foramina. The nerves which pass through the spinal region of this series of foramina above and below C are continuous with the nerves which pass through the cranial region. The anterior boundary, D I, of the cervical spine is continuous with the anterior boundary, Y F, of the cranial cavity. And this common serial order of osseous parts—viz., the bodies of vertebrae, serves to isolate the cranio-spinal compartment from the facial and cervical passages. Thus the anterior boundary, Y F D I, of the cranio-spinal canal is also the posterior boundary of the facial and cervical cavities.

Now as the cranio-spinal chamber is lined by the common dura-matral membrane, and contains the common mass of nervous structure, thus inviting us to fix attention upon this structure as a whole, so we find that the frontal cavity, Z, the nasal cavity, X W, the oral cavity, 4, 5, S, the pharyngeal and oesophageal passages 8 Q, are lined by the common mucous membrane, and communicate so freely with each other that they may be in fact considered as forming a common cavity divided only by partially formed septa, such as the one, U V, which separates to some extent the nasal fossa from the oral fossa.

As owing to this continuity of structure, visible between the head and spine, we may infer the liability which the affections of the one region have to pass into and implicate the other, so likewise by that continuity apparent between all compartments of the face, fauces, oesophagus, and larynx, we may estimate how the pathological condition of the one region will concern the others.

The cranium, owing to its comparatively superficial and undefended condition, is liable to fracture. When the cranium is fractured, in consequence of force applied to its anterior or posterior surfaces, A or B, Plate 20, the fracture will, for the most part, be confined to the place whereat the force has been applied, provided the point opposite has not been driven against some resisting body at the same time. Thus when the point B is struck by a force sufficient to fracture the bone, while the point A is not opposed to any resisting body, then B alone will yield to the force applied; and fracture thus occurring at the point B, will have happened at the place where the applied force is met by the force, or weight, or inertia of the head itself. But when B is struck by any ponderous body, while A is at the same moment forced against a resisting body, then A is also liable to suffer fracture. If fracture in one place be attended with counter-fracture in another place, as at the opposite points A and B, then the fracture occurs from the force impelling, while the counter-fracture happens by the force resisting.

Now in the various motions which the cranium A A B performs upon the top of the cervical spine C, motions backwards, forwards, and to either side, it will follow that, taking C as a fixed point, almost all parts of the cranial periphery will be brought vertical to C in succession, and therefore whichever point happens at the moment to stand opposite to C, and has impelling force applied to it, then C becomes the point of resistance, and thus counter-fractures at the cranial base occur in the neighbourhood of C. When force is applied to the cranial vertex, whilst the body is in the erect posture, the top of the cervical spine, E D C, becomes the point of resistance. Or if the body fall from a height upon its cranial vertex, then the propelling force will take effect at the junction of the spine with the cranial base, whilst the resisting force will be the ground upon which the vertex strikes. In either case the cranial base, as well as the vertex, will be liable to fracture.

The anatomical form of the cranium is such as to obviate a frequent liability to fracture. Its rounded shape diffuses, as is the case with all rotund forms, the force which happens to strike upon it. The mode in which the cranium is set upon the cervical spine serves also to diffuse the pressure at the points where the two opposing forces meet—viz., at the first cervical vertebra E and the cranial basilar process F. This fact might be proved upon mechanical principle.

The tegumentary envelope of the head, as well as the dura-matral lining, serves to damp cranial vibration consequent upon concussion; while the sutural isolation of the several component bones of the cranium also prevents, in some degree, the extension of fractures and the vibrations of concussion. The contents of the head, like the contents of all hollow forms, receive the vibratory influence of force externally applied. The brain receives the concussion of the force applied to its osseous envelope; and when this latter happens to be fractured, the danger to life is not in proportion to the extent of the fracture here, any more than elsewhere in the skeleton fabric, but is solely in proportion to the amount of shock or injury sustained by the nervous centre.

When it is required to trephine any part of the cranial envelope, the points which should be avoided, as being in the neighbourhood of important bloodvessels, are the following—the occipital protuberance, B, within which the “torcular Herophili” is situated, and from this point passing through the median line of the vertex forwards to Z the frontal sinus, the trephine should not be applied, as this line marks the locality of the superior longitudinal sinus. The great lateral sinus is marked by the superior occipital ridge passing from the point B outwards to the mastoid process. The central point B of the side of the head, Plate 21, marks the locality of the root of the meningeal artery within the cranium, and from this point the vessel branches forwards and backwards over the interior of the cranium.

The nasal fossae are situated on either side of the median partition formed by the vomer and cartilaginous nasal septum. Both nasal fossae are open anteriorly and posteriorly; but laterally they do not, in the normal state of these parts, communicate. The two posterior nares answering to the two nasal fossae open into the upper part of the bag of the pharynx at 8, Plate 20, which marks the opening of the Eustachian tube.

The structures observable in both the nasal fossae absolutely correspond, and the foramina which open into each correspond likewise. All structures situated on either side of the median line are similar. And the structure which occupies the median line is itself double, or duality fused into symmetrical unity. The osseous nasal septum is composed of two laminae laid side by side. The spongy bones, X W, are attached to the outer wall of the nasal fossa, and are situated one above the other. These bones are three in number, the uppermost is the smallest. The outer wall of each naris is grooved by three fossae, called meatuses, and these are situated between the spongy bones. Each meatus receives one or more openings of various canals and cavities of the facial apparatus. The sphenoidal sinus near F opens into the upper meatus. The frontal, Z, and maxillary sinuses open into the middle meatus, and the nasal duct opens into the inferior sinus beneath the anterior inferior angle of the lower spongy bone, W.

In the living body the very vascular fleshy and glandular Schneiderian membrane which lines all parts of the nasal fossa almost completely fills this cavity. When polypi or other growths occupy the nasal fossae, they must gain room at the expense of neighbouring parts. The nasal duct may have a bent probe introduced into it by passing the instrument along the outer side of the floor of the nasal fossa as far back as the anterior inferior angle of the lower spongy bone, W, at which locality the duct opens. An instrument of sufficient length, when introduced into the nostrils in the same direction, will, if passed backwards through the posterior nares, reach the opening of the Eustachian tube, 8.

While the jaws are closed, the tongue, R, Plate 20, occupies the oral cavity almost completely. When the jaws are opened they form a cavity between them equal in capacity to the degree at which they are sundered from each other. The back of the pharynx can be seen when the jaws are widely opened if the tongue be depressed, as R, Plate 20. The hard palate, U, which forms the roof of the mouth, is extended further backwards by the soft palate, V, which hangs as the loose velum of the throat between the nasal fossae above and the fauces below. Between the velum palati, V, and the root of the tongue, we may readily discern, when the jaws are open, two ridges of arching form, 5, 6, on either side of the fauces. These prominent arches and their fellows are named the pillars of the fauces. The anterior pillar, 5, is formed by the submucous palato-glossus muscle; the posterior pillar, 6, is formed by the palato-pharyngeus muscle. Between these pillars, 5 and 6, is situated the tonsil, S, beneath the mucous membrane. When the tonsils of opposite sides become inflamed and suppurate, an incision may be made into either gland without much chance of wounding the internal carotid artery; for, in fact, this vessel lies somewhat removed from it behind. In Plate 21, that point of the superior constrictor of the pharynx, marked D, indicates the situation of the tonsil gland; and a considerable interval will be seen to exist between D and the internal carotid vessel F.

If the head be thrown backwards the nasal and oral cavities will look almost vertically towards the pharyngeal pouch. When the juggler is about to “swallow the sword,” he throws the head back so as to bring the mouth and fauces in a straight line with the pharynx and oesophagus. And when the surgeon passes the probang or other instruments into the oesophagus, he finds it necessary to give the head of the person on whom he operates the same inclination backwards. When instruments are being passed into the oesophagus through the nasal fossa, they are not so likely to encounter the rima glottidis below the epiglottis, 9, as when they are being passed into the oesophagus by the mouth. The glottis may be always avoided by keeping the point of the instrument pressing against the back of the pharynx during its passage downwards.

When in suspended animation we endeavour to inflate the lungs through the nose or mouth, we should press the larynx, 10, 11,12, backwards against the vertebral column, so as to close the oesophageal tube.

DESCRIPTION OF PLATES 20 & 21.

PLATE 20.

A A. The dura-matral falx; A*, its attachment to the tentorium.

B. Torcular Herophili.

C. Dura-mater lining the spinal canal.

D D*. Axis vertebra.

E E*. Atlas vertebra.

F F*. Basilar processes of the sphenoid and occipital bones.

G. Petrous part of the temporal bone.

H. Cerebellar fossa.

I I*. Seventh cervical vertebra.

K K*. First rib surrounding the upper part of the pleural sac.

L L*. Subclavian artery of the right side overlying the pleural sac.

M M*. Right subclavian vein.

N. Right common carotid artery cut at its origin.

O. Trachea.

P. Thyroid body.

Q. Oesophagus.

R. Genio-hyo-glossus muscle.

S. Left tonsil beneath the mucous membrane.

T. Section of the lower maxilla.

U. Section of the upper maxilla.

V. Velum palati in section.

W. Inferior spongy bone.

X. Middle spongy bone.

Y. Crista galli of oethmoid bone.

Z. Frontal sinus.

2. Anterior cartilaginous part of nasal septum.

3. Nasal bone.

4. Last molar tooth of the left side of lower jaw.

5. Anterior pillar of the fauces.

6. Posterior pillar of the fauces.

7. Genio-hyoid muscle.

8. Opening of Eustachian tube.

9. Epiglottis.

10. Hyoid bone.

11. Thyroid bone.

12. Cricoid bone.

13. Thyroid axis.

14. Part of anterior scalenus muscle.

15. Humeral end of the clavicle.

16. Part of posterior scalenus muscle.

Plate 20

PLATE 21.

A. Zygoma.

B. Articular glenoid fossa of temporal bone.

C. External pterygoid process lying on the levator and tensor palati muscles.

D. Superior constrictor of pharynx.

E. Transverse process of the Atlas.

F. Internal carotid artery. Above the point F, is seen the glosso-pharyngeal nerve; below F, is seen the hypoglossal nerve.

G. Middle constrictor of pharynx.

H. Internal jugular vein.

I. Common carotid cut across.

K. Rectus capitis major muscle.

L. Inferior constrictor of pharynx.

M. Levator anguli scapulae muscle.

N. Posterior scalenus muscle.

O. Anterior scalenus muscle.

P. Brachial plexus of nerves.

Q. Trachea.

R R*. Subclavian artery.

S. End of internal jugular vein.

T. Bracheo-cephalic artery.

U U*. Roots of common carotid arteries.

V. Thyroid body.

W. Thyroid cartilage.

X. Hyoid bone.

Y. Hyo-glossus muscle.

Z. Upper maxillary bone.

2. Inferior maxillary branch of fifth cerebral nerve.

3. Digastric muscle cut.

4. Styloid process.

5. External carotid artery.

6 6. Lingual artery.

7. Roots of cervical plexus of nerves.

8. Thyroid axis; 8*, thyroid artery, between which and Q, the trachea, is seen the inferior laryngeal nerve.

9. Omo-hyoid muscle cut.

10. Sternal end of clavicle.

11. Upper rings of trachea, which may with most safety be divided in tracheotomy.

12. Cricoid cartilage.

13. Crico-thyroid interval where laryngotomy is performed.

14. Genio-hyoid muscle.

15. Section of lower maxilla.

16. Parotid duct.

17. Lingual attachment of styloglossus muscle, with part of the gustatory nerve seen above it.

Plate 21

COMMENTARY ON PLATE 22.

THE RELATIVE POSITION OF THE SUPERFICIAL ORGANS OF THE THORAX AND ABDOMEN.

In the osseous skeleton, the thorax and abdomen constitute a common compartment. We cannot, while we contemplate this skeleton, isolate the one region from the other by fact or fancy. The only difference which I can discover between the regions called thorax and abdomen, in the osseous skeleton, (considering this body morphologically,) results, simply, from the circumstance that the ribs, which enclose thoracic space, have no osseous counterparts in the abdomen enclosing abdominal space, and this difference is merely histological. In man and the mammalia the costal arches hold relation with the pulmonary organs, and these costae fail at that region where the ventral organs are located. In birds, and many reptiles, the costal arches enclose the common thoracico-abdominal region, as if it were a common pulmonary region. In fishes the costal arches enclose the thoracico-abdominal region, just as if it were a common abdominal region. I merely mention these general facts to show that costal enclosure does not actually serve to isolate the thorax from the abdomen in the lower classes of animals; and on turning to the human form, I find that this line of separation between the two compartments is so very indefinite, that, as pathologists, we are very liable to err in our diagnosis between the diseased and the healthy organs of either region, as they lie in relation with the moveable diaphragm or septum in the living body. The contents of the whole trunk of the body from the top of the sternum to the perineum are influenced by the respiratory motions; and it is most true that the diaphragmatic line, H F H*, is alternately occupied by those organs situated immediately above and below it during the performance of these motions, even in health.

The organs of the thoracic region hold a certain relation to each other and to the thoracic walls. The organs of the abdomen hold likewise a certain relation to each other and to the abdominal parietes. The organs of both the thorax and the abdomen have a certain relation to each other, as they lie above and below the diaphragm. In dead nature these relations are fixed and readily ascertainable, but in living, moving nature, the organs influence this relative position, not only of each other, but also of that which they bear to the cavities in which they are contained. This change of place among the organs occurs in the normal or healthy state of the living body, and, doubtless, raises some difficulty in the way of our ascertaining, with mathematical precision, the actual state of the parts which we question, by the physical signs of percussion and auscultation. In disease this change of place among these organs is increased, and the difficulty of making a correct diagnosis is increased also in the same ratio. For when an emphysematous lung shall fully occupy the right thoracic side from B to L, then G, the liver, will protrude considerably into the abdomen beneath the right asternal ribs, and yet will not be therefore proof positive that the liver is diseased and abnormally enlarged. Whereas, on the other hand, when G, the liver, is actually diseased, it may occupy a situation in the right side as high as the fifth or sixth ribs, pushing the right lung upwards as high as that level; and, therefore, while percussion elicits a dull sound over this place thus occupied, such sound will not be owing to a hepatized lung, but to the absence of the lung caused by the presence of the liver.

In the healthy adult male body, Plate 22, the two lungs, D D*, whilst in their ordinary expanded state, may be said to range over all that region of the trunk of the body which is marked by the sternal and asternal ribs. The heart, E, occupies the thoracic centre, and part of the left thoracic side. The heart is almost completely enveloped in the two lungs. The only portion of the heart and pericardium, which appears uncovered by the lung on opening the thorax, is the base of the right ventricle, E, situated immediately behind the lower end of the sternum, where this bone is joined by the cartilages of the sixth and seventh ribs. The lungs range perpendicularly from points an inch above B, the first rib, downwards to L, the tenth rib, and obliquely downwards and backwards to the vertebral ends of the last ribs. This space varies in capacity, according to the degree in which the lungs are expanded within it. The increase in thoracic space is attained, laterally, by the expansion of the ribs, C I; and vertically, by the descent of the diaphragm, H, which forces downwards the mass of abdominal viscera. The contraction of thoracic space is caused by the approximation of all the ribs on each side to each other; and by the ascent of the diaphragm. The expansion of the lungs around the heart would compress this organ, were it not that the costal sides yield laterally while the diaphragm itself descends. The heart follows the ascent and descent of the diaphragm, both in ordinary and forced respiration.

But however much the lungs vary in capacity, or the heart as to position in the respiratory motions, still the lungs are always closely applied to the thoracic walls. Between the pleura costalis and pulmonalis there occurs no interval in health. The thoracic parietes expand and contract to a certain degree; and to that same degree, and no further, do the lungs within the thorax expand and contract. By no effort of expiration can the animal expel all the air completely from its lungs, since by no effort of its own, can it contract thoracic space beyond the natural limit. On the other hand, the utmost degree of expansion of which the lungs are capable, exactly equals that degree in which the thoracic walls are dilatable by the muscular effort; and, therefore, between the extremes of inspiration and expiration, the lungs still hold closely applied to the costal parietes. The air within the lungs is separated from the air external to the thorax, by the thoracic parietes. The air within and external to the lungs communicate at the open glottis. When the glottis closes and cuts off the communication, the respiratory act ceases—the lungs become immovable, and the thoracic walls are (so far as the motions of respiration are concerned) rendered immovable also. The muscles of respiration cannot, therefore, produce a vacuum between the pulmonic and costal pleura, either while the external air has or has not access to the lungs. Upon this fact the mechanism of respiration mainly depends; and we may see a still further proof of this in the circumstance that, when the thoracic parietes are pierced, so as to let the external air into the cavity of the pleura, the lung collapses and the thoracic side ceases to exert an expansile influence over the lung. When in cases of fracture of the rib the lung is wounded, and the air of the lung enters the pleura, the same effect is produced as when the external air was admitted through an opening in the side.

When serous or purulent effusion takes place within the cavity of the pleura, the capacity of the lung becomes lessened according to the quantity of the effusion. It is more reasonable to expect that the soft tissue of the lung should yield to the quantity of fluid within the pleural cavity, than that the rigid costal walls should give way outwardly; and, therefore, it seldom happens that the practitioner can discover by the eye any strongly-marked difference between the thoracic walls externally, even when a considerable quantity of either serum, pus, or air, occupies the pleural sacs.

In the healthy state of the thoracic organs, a sound characteristic of the presence of the lung adjacent to the walls of the thorax may be elicited by percussion, or heard during the respiratory act through the stethoscope, over all that costal space ranging anteriorly between B, the first rib, and I K, the eight and ninth ribs. The respiratory murmur can be heard below the level of these ribs posteriorly, for the lung descends behind the arching diaphragm as far as the eleventh rib.

When fluid is effused into the pleural cavity, the ribs are not moved by the intercostal muscles opposite the place occupied by the fluid, for this has separated the lung from the ribs. The fluid has compressed the lung; and in the same ratio as the lung is prevented from expanding, the ribs become less moveable. The presence of fluid in the pleural sac is discoverable by dulness on percussion, and, as might be expected, by the absence of the respiratory murmur at that locality which the fluid occupies. Fluid, when effused into the pleural sac, will of course gravitate; and its position will vary according to the position of the patient. The sitting or standing posture will therefore suit best for the examination of the thorax in reference to the presence of fluid.

Though the lungs are closely applied to the costal sides at all times in the healthy state of these organs, still they slide freely within the thorax during the respiratory motions—forwards and backwards—over the serous pericardium, E, and upwards and downwards along the pleura costalis. The length of the adhesions which supervene upon pleuritis gives evidence of the extent of these motions. When the lung becomes in part solidified and impervious to the inspired air, the motions of the thoracic parietes opposite to the part are impeded. Between a solidified lung and one which happens to be compressed by effused fluid it requires no small experience to distinguish a difference, either by percussion or the use of the stethoscope. It is great experience alone that can diagnose hydro-pericardium from hypertrophy of the substance of the heart by either of these means.

The thoracic viscera gravitate according to the position of the body. The heart in its pericardial envelope sways to either side of the sternal median line according as the body lies on this or that side. The two lungs must, therefore, be alternately affected as to their capacity according as the heart occupies space on either side of the thorax. In expiration, the heart, E, is more uncovered by the shelving edges of the lungs than in inspiration. In pneumothorax of either of the pleural sacs the air compresses the lung, pushes the heart from its normal position, and the space which the air occupies in the pleura yields a clear hollow sound on percussion, whilst, by the ear or stethoscope applied to a corresponding part of the thoracic walls, we discover the absence of the respiratory murmur.

The transverse diameter of the thoracic cavity varies at different levels from above downwards. The diameter which the two first ribs, B B*, measure, is the least. That which is measured by the two eighth ribs, I I*, is the greatest. The perpendicular depth of the thorax, measured anteriorly, ranges from A, the top of the sternum, to F, the xyphoid cartilage. Posteriorly, the perpendicular range of the thoracic cavity measures from the spinous process of the seventh cervical vertebra above, to the last dorsal spinous process below. In full, deep-drawn inspiration in the healthy adult, the ear applied to the thoracic walls discovers the respiratory murmur over all the space included within the above mentioned bounds. After extreme expiration, if the thoracic walls be percussed, this capacity will be found much diminished; and the extreme limits of the thoracic space, which during full inspiration yielded a clear sound, indicative of the presence of the lung, will now, on percussion, manifest a dull sound, in consequence of the absence of the lung, which has receded from the place previously occupied.

Owing to the conical form of the thoracic space, the apex of which is measured by the first ribs, B B*, and the basis by I I*, it will be seen that if percussion be made directly from before, backwards, over the pectoral masses, R R*, the pulmonic resonance will not be elicited. When we raise the arms from the side and percuss the thorax between the folds of the axillae, where the serratus magnus muscle alone intervenes between the ribs and the skin, the pulmonic sound will answer clearly.

At the hypochondriac angles formed between the points F, L, N, on either side the lungs are absent both in inspiration and expiration. Percussion, when made over the surface of the angle of the right side, discovers the presence of the liver, G G*. When made over the median line, and on either side of it above the umbilicus, N, we ascertain the presence of the stomach, M M*. In the left hypochondriac angle, the stomach may also be found to occupy this place wholly.

Beneath the umbilicus, N, and on either side of it as far outwards as the lower asternal ribs, K L, thus ranging the abdominal parietes transversely, percussion discovers the transverse colon, O, P, O*. The small intestines, S S*, covered by the omentum, P*, occupy the hypogastric and iliac regions.

The organs situated within the thorax give evidence that they are developed in accordance to the law of symmetry. The lungs form a pair, one placed on either side of the median line. The heart is a double organ, formed of the right and left heart. The right lung differs from the left, inasmuch as we find the former divided into three lobes, while the latter has only two. That place which the heart now occupies in the left thoracic side is the place where the third or middle lobe of the left lung is wanting. In the abdomen we find that most of its organs are single. The liver, stomach, spleen, colon, and small intestine form a series of single organs: each of these may be cleft symmetrically. The kidneys are a pair.

The extent to which the ribs are bared in the figure Plate 22, marks exactly the form and transverse capacity of the thoracic walls. The diaphragm, H H*, has had a portion of its forepart cut off, to show how it separates the thin edges of both lungs above from the liver, G, and the stomach, M, below. These latter organs, although occupying abdominal space, rise to a considerable height behind K L, the asternal ribs, a fact which should be borne in mind when percussing the walls of the thorax and abdomen at this region.