In the middle third of the forearm, the inner edge of the supinator radii longus marks the line of the incision, which should be to the extent of three inches. The fascia being divided, the supinator longus is to be separated from the flexor carpi radialis, and, on the division of the deep fascia, the artery will be found passing with its venæ comites over the insertion of the pronator radii teres and the radial origin of the flexor digitorum sublimis. The musculo-spiral nerve lies close to the radial side of the artery.
Near the wrist, the radial artery may be tied with great facility. Make an incision two inches and a half long on the radial side of the tendon of the flexor carpi radialis, which becomes prominent on bending the wrist; the superficial and deep fasciæ are to be divided, when the artery and its veins will be exposed; the nerve has not accompanied the artery to this point, where it lies on the pronator quadratus, whence it turns below the styloid process of the radius to the back of the hand.
The radial artery, on giving off the superficialis volæ to the palm of the hand, near the end of the radius, inclines outward, and, when between its styloid process and the trapezium, lies beneath the two first extensors of the thumb. Passing onward to reach the angle formed by the metacarpal bones of the thumb and forefinger, it lies first in a triangular space between these two extensor muscles and the third, in which situation a ligature may readily be placed upon it by a simple incision. Proceeding onward, the artery passes under the third extensor and lies to the outside of it, where it may also be secured by ligature without difficulty, just before it dips into the palm and gives off the principal artery to the thumb. After the radial artery has reached the inside of the hand, to form the deep-seated palmar arch, it crosses the metacarpal bones nearly at a right angle, covered by all the muscles, tendons, and nerves of the palm. A branch of the ulnar nerve is here seen going to the muscles of the thumb. If the graduated compression recommended in Aphorism 208, page 238, together with due pressure on the radial and ulnar arteries at the wrist, should fail to arrest the bleeding from a wound at this part, the two muscles, forming what may be and is called the web, between the thumb and forefinger should be divided until the wounded artery can be seen. These muscles are the adductor pollicis on the inside, and the adductor indicis on the back of the hand; and their division would lead to little or no inconvenience. If a man, in opening an oyster, were to divide these muscles by an accidental thrust of his knife, it would not be considered a serious accident, although some surgeons might be dismayed if desired to divide them surgically, to expose the artery at the spot where it has been wounded.
LECTURE XVI.
INJURIES OF THE BRAIN.
242. Injuries of the head affecting the brain are difficult of distinction, doubtful in their character, treacherous in their course, and for the most part fatal in their results. The symptoms which appear especially to indicate one kind of accident are frequently met with in another. It may even be said that there is no one symptom which is presumed to demonstrate a particular lesion of the brain, which has not been shown to have taken place in another of a different kind. Examination after death has often proved the presence of a most serious injury the existence of which had not even been suspected; and death has often ensued immediately, or shortly after the most marked and alarming symptoms, without any adequate cause for the event being discovered on dissection. One man shall lose a considerable portion of his brain without its being productive at the moment of the slightest apparent functional inconvenience; while another shall fall, and shortly die without an effort at recovery, in spite of any treatment which may be bestowed upon him, after a very much slighter injury inflicted apparently on the same part. During the war with the United States, in 1814, a soldier in Canada was struck by a ball which lodged in the posterior part of the side of the head; the wound healed, and the man returned to his duty. Twelve months afterward, having got drunk, he fell in the streets of Montreal, and died. The ball was found lying on the corpus callosum, where it had made a small hole or sac for itself. After the battle of Waterloo, I recommended, in the case of a soldier similarly wounded, that nothing should be done unless symptoms arose demanding the use of the trephine; as none occurred, and the wound healed, the man was sent home to Colchester, where he got drunk, and fell dead in the marketplace. The ball was lodged deeply in a cyst in the posterior lobe of the brain. Persons rarely live with a foreign body lodged in the anterior lobe of the brain, although many recover with the loss of a portion of the brain at that part. An injury of apparently equal extent is more dangerous on the forehead than on the side or middle of the head, and much less so on the back part than on the side. A fracture of the vertex is of infinitely less importance than one at the base of the cranium, which, although not necessarily fatal, is always attended with the utmost danger. The treatment of these several injuries (although they may be at first sight apparently similar) cannot, and must not be alike in all—a fact which should always be borne in mind in their management. In civil life, both in hospitals and among private persons, injuries of the base of the cranium are most frequently met with, because they are generally the consequence of falls; while in military life injuries of the base of the skull are rare, and those of other parts are common. The practice of the military surgeon, with respect to injuries of the cranium and its contents, is therefore more successful, all things considered, than that of the surgeon in civil life, and particularly in a great metropolis; this may perhaps account for some of the discrepancies in opinion which have existed between them.
243. Many physiologists have thought they could indicate the part of the brain injured from the symptoms which followed, and there are some which do not admit of dispute as to their cause; but there are very many which at present do not admit of being distinctly traced to their source. Birds, small quadrupeds, fishes, and reptiles will live for some weeks after nearly all the contents of the skull have been removed. Sensation, volition, memory, judgment, sight, hearing, and all other sensations are lost by the removal of the cerebral hemispheres. The mobility of the iris is destroyed, not by the removal of the hemispheres, but of the corpora quadrigemina. If the cerebellum be cut away, a bird can no longer jump, walk, or retain its natural position, but it can move and live. When the medulla oblongata, or medulla spinalis, or the nerves of these parts, have been divided, muscular contraction ceases, and all power of movement is lost. Life is destroyed because respiration ceases when the medulla oblongata is divided at or immediately below the origin of the eighth pair of nerves. The removal of any one of these nervous parts in the lower animals only weakens the powers of those which remain. In man it destroys them, and life is extinguished.
244. Respiration consists of four movements—1, the opening of the mouth and dilatation of the nostrils; 2, the opening of the glottis; 3, the elevation of the ribs; 4, the contraction of the diaphragm. The division of the dorsal spinal marrow, below the origin of the phrenic nerve, paralyzes the movement of the ribs; above the phrenic nerves it paralyzes the diaphragm, and respiration ceases; the yawning or opening of the mouth and glottis alone remain. On dividing the point of origin of the par vagum, the movements of the glottis cease. On slicing the upper part of the medulla oblongata instead of the lower, from before backward, the opening or yawning of the mouth ceases; another slice, and the dilatations of the nose are arrested, and the inspiratory movements of the trunk alone remain.
While the power of motion in each part seems thus to be dependent on isolated points of the medulla oblongata and the medulla spinalis, an indirect or connecting influence is admitted to take place between them and the remaining parts of the brain; and whatever may be its nature or extent in animals, there can be no doubt of its being so infinitely greater in man as to be essentially different; for none of these experiments can be made either artificially or accidentally on any one of these parts in him, without being productive of the ultimate if not almost immediate death of the whole.
Dr. Marshall Hall, in the comprehensive and luminous view he has taken of the nervous system, supposes that each sentient and motor nerve of the spinal marrow is further endowed with an excito-motor power for reflex action. He calls these generally excito-motor nerves, and considers them to be connected with a part of the medulla spinalis, distinct from that portion which is strictly an appendage to the brain. Incident nerves arise from the skin and certain mucous membranes, and convey impressions from them to the spinal marrow. Reflex nerves convey back the nervous influence excited through the medium of the incident nerves, to the voluntary muscles in which they terminate; and Dr. Marshall Hall further considers that these nerves, and the part he calls the true spinal cord, constitute the true spinal system which presides over ingestion and exclusion, retention and egestion; and consequently that its influence is exerted upon the muscles which belong to the entrances and outlets of the animal frame; or, in other words, upon the sphincters, and the muscles of deglutition and of respiration; and that the true spinal system maintains the tone of the whole muscular system. Stimulating an incident or excitor nerve of the extremities, by tickling or pricking the sole of the foot or the palm of the hand after sensation is apparently destroyed, causes a special muscular contraction or motion in the limb, if the excito-motor system be uninjured. Irritating the eyelashes induces contraction of the eyelids; and the irritation of one will sometimes cause contraction of both. Tickling the verge of the anus induces contraction of the sphincter muscle. Irritating the fauces and the root of the tongue, by pressing it down with the handle of a spoon, induces an action of deglutition. Respiration is excited by irritating or exciting the trifacial or fifth pair of nerves, by throwing cold water on the face, and stimulating the nostrils; by influencing the spinal nerves by a similar use of cold water to the body and chest, and by tickling or stimulating the sides, soles of the feet, and verge of the anus.