The Matron's Manual of Midwifery, and the Diseases of Women During Pregnancy and in Childbed / Being a Familiar and Practical Treatise, More Especially Intended for the Instruction of Females Themselves, but Adapted Also for Popular Use among Students and Practitioners of Medicine

by Frederick Hollick

SECTION III.

THE FORM, SIZE, AND POSITION OF THE FŒTUS, AND ITS APPENDAGES, AT FULL TERM.

CHAPTER VIII.

FORM AND SIZE OF THE FŒTUS AT FULL TERM.

SIZE AND FORM OF THE BODY.

The average length of the Fœtus, at full term, is about twelve inches from the head to the breech, and about eighteen inches from the head to the feet. Its weight varies from five to eight pounds, perhaps averaging about six, though some have been born weighing only three pounds, or less, and some even as high as twelve. The breadth across the shoulders is about four inches, and the same across the hips, but both are so easily compressed that during delivery they only measure about three inches, or three and a half at most.

SIZE AND FORM OF THE HEAD.

The head is the most important part, because it is the largest, and usually present first. It is therefore necessary to describe it fully, and with special reference to its importance, in the early stages of labor, as the part by which the position is usually determined.

PLATE XXIV.

The head is generally divided into the Cranium, or that part which contains the brain, and the Face.

The Bones of the Cranium.—These are seven in number, viz., two Frontal Bones, or those forming the forehead; 1, 1, Figs. 1 and 2, (Plate XXIV.)—Two Parietal bones, or those forming the sides of the head; 2, 2, Figs. 1 and 2.—The Occipital bone, or that forming the back of the head; 3, 3, Figs. 1 and 2.—And two Temporal bones, which lie over and between the ear and the eye; 4, Fig. 2.

The Bones of the Face.—These are five in number, viz., two Superior Maxillary, or upper jaw bones; 5, Fig. 2.—Two Malar, or cheek bones; 6, Fig. 2.—And one Inferior Maxillary, or lower jaw bone; 7, Fig. 2.

the fœtal head.

Plate XXIV.

The head is generally divided into the Cranium, or that part which contains the brain, and the Face.

The bones of the cranium are not closed together, as they are in the adult, but are separated to a considerable distance, in certain parts, and connected by a strong membrane. These membranous spaces are called Sutures and Fontanelles, and a knowledge of them is absolutely necessary, as a means of ascertaining the position of the head.

The Sutures.—The first of these spaces, which extends from the lowest part of the middle of the forehead to the occipital bone, is called the Sagittal Suture, or antero posterior Suture: A, B, C, Figs. 1 and 2. It separates the two frontal, and the two parietal bones. The spaces between the two frontal and the two parietal bones are called the Frontal Parietal Sutures, o. o. Fig. 1; and those between the two parietal bones and the occipital, l. l. Figs. 1 and 2, are called the Lambdoidal Sutures.

The Fontanelles.—When the different Sutures meet at a point, the membranous space is greater than at other parts, and is called a Fontanelle. Thus when the two Frontal Parietal Sutures meet the Sagittal Suture, at B, Figs. 1 and 2, there is quite a large diamond shaped space between the different bones, filled up with membrane. This is called the Anterior Fontanelle, or bregma. Where the Sagittal Suture joins the two Lambdoidal there is another space, not so large, and different in shape, being triangular; this is called the Posterior Fontanelle, c. Figs. 1 and 2. And where each of the temporal bones joins the parietal there are two other spaces, called the Temporal Fontanelles, t. Fig. 2, which are also irregularly diamond shaped, but not nearly so large as the anterior fontanelle.

It is evident that if a person can distinguish these Fontanelles, when he touches them with his finger, he can tell what part of the head is presenting, and hence their use.

These spaces allow of the bones lapping over each other, during delivery, and thus the head is made smaller. They do not disappear till sometime after birth, and in very young children the brain may be felt, and seen to work, at the anterior fontanelle. Eventually however, the bones come close together, and are joined by a curious kind of dovetailing. The two frontal bones however, completely coalesce, and form but one, in the adult.

Sometimes the bones will be very perfectly formed, and the fontanelles nearly filled up, before birth, and then the head cannot be crushed much smaller, and so the labor becomes both painful and difficult. This is usually called an ossified, or solid head.

Diameters of the Head.—The diameters of the head are the distances between its most prominent points. They are necessary to be known before we can judge as to the possibility of its passing the straits of the Pelvis, in the various positions.

Generally there are reckoned ten diameters, and they are represented in the following Plate:—

PLATE XXV.

Diameters of the Head.

Fig. 1.

Fig. 2.

1. The Occipito Mental, or from the back of the head to the chin, M, O, Fig. 1, five inches.

2. The Mento Bregmatic, or from the chin to the anterior fontanelle at the top of the head, M, O, Fig. 1, four inches.

3. The Occipito Frontal, or from the back of the head to the top of the forehead, O, F, Fig. 1, four inches.

4. The Trachelo Occipital, or from the throat to the back of the head, T, O, Fig. 1, four inches.

5. The Sub Occipito Bregmatic, or from the nape of the neck to the top of the head, S, B, Fig. 1, three inches and a half.

6. The Trachelo Bregmatic, or from the top of the throat to the top of the head, T, B, Fig. 1, about three inches and a half.

7. The Trachelo Frontal, or from the top of the throat to the top of the forehead, T, F, Fig. 1, about three inches.

8. The Sub Occipito Frontal, or from the nape of the neck to the top of the forehead, S, F, Fig. 1, about three inches.

9. The Bi Parietal, or across the head from one side to the other at the middle of the parietal bones, the widest part, B, P, Fig. 2, three inches and a quarter to three and a half.

10. The Bi Temporal, or across the head from one temporal bone to the other, B, T, Fig. 2, about two inches and a half.

The necessity for knowing these diameters will be obvious. It is only by being acquainted with them, and with the straits of the Pelvis, already described, that we can tell whether the child can pass or not in certain positions, and how we must change its position, when possible, to give relief.

On comparing the diameters of the head with those of the Pelvis, it will be seen that some of them correspond in size while others do not, so that in one position delivery can take place spontaneously, while in another it will be difficult, and in some nearly impossible, without assistance. Thus, for instance, if the head should present by the occipito mental diameter, (O, M, Fig. 1,) it evidently could not pass while in that position, because by this diameter it is five inches in width, and the greatest diameter of the Pelvis is only about four inches and a half. Its position must therefore be changed, and the accoucheur must know how to change it with advantage.

ATTITUDE OF THE FŒTUS AT FULL TERM.

The attitude of the Fœtus is represented in the following Plate:—

PLATE XXVI.

Attitude of the Fœtus.

The arms, it will be seen, are crossed on the breast, upon which the chin is also bent; the thighs are close together, and brought against the Abdomen; the legs are close bent on the Thighs, and the feet are turned up against the front of the legs, the whole body being curved forward.

The position in which the Fœtus most usually lies in the Womb has already been shown, particularly in Plate XII, and in Plate XVI. The head is downwards, and the back part of it turned to the mother's left side. What is the cause of this almost universal position is not certainly known. It was formerly thought to depend on the head being heavier than the other parts, and thus sinking down; but this supposition has been shown to be entirely without foundation. M. P. Dubois has lately advanced the notion that it depends on an instinctive feeling in the Fœtus itself, which directs it to take that position by which it can most easily make its exit. This opinion appears very reasonable, and is apparently well founded. It is well known that the Fœtus is susceptible of various impressions while in the Womb, and impelled by unerring instinct to take the breast immediately it is born; nay, it has even been known to suck the finger of the assistant, in cases of face presentation, even before birth! We can readily believe, therefore, that it is directed to place itself in the Womb, in the best position, the same as it is directed to take the finger in its mouth.

In the young of many of the lower animals this is also strikingly exemplified. The young duck in the shell taps with its little beak against the part that is to be broken, and rushes into the water even with a part of the shell still on its back. The young oppossums, who are born imperfect from the Womb, shelter themselves, immediately they come into the world, in the pouch on the mother's breast, and fasten themselves to the mammæ till they are more perfectly grown.

It must be remarked however, that the head does not always present first, though it usually does so. Occasionally we have the breech present, and still rarer even other parts; but these are merely exceptional deviations, the causes of which are unknown. Out of every sixteen children born, fifteen usually come head first. This however, will be shown better further on.

CHAPTER IX.

THE APPENDAGES OF THE FŒTUS AT TERM.

THE MEMBRANES.

The uses and arrangements of the membranes surrounding the Fœtus have already been explained, so that little more is needed to be said here, because they are not much different at the full term from what they are at an earlier period, excepting perhaps that the amnion is a little more dense and firm. This membrane appears not only to surround the Fœtus like a bag, to contain the waters, but is also reflected close on to its body, like its skin, with which in fact it is thought by some to be connected. The child is certainly born with this membrane still on its body, and does not part with it till some days after birth, when it peels off like a thin dead skin, or powder.

The waters, enclosed within the Amnion, (see Plate [XII],) have now increased to their greatest quantity; and there is also, in most cases, a second body of fluid between the Amnion and the Chorion, which coming away before the real discharge, is called the false waters.—(See Plate [XII].)

The quantity of the true waters, at birth, is about twenty, or from that to thirty ounces, but is very variable. It is of a greenish color, rather muddy, and heavier than water. It contains albumen, (white of egg,) sulphate of soda, and lime. Ninety-eight per cent. of it however, is pure water. It appears to be excreted, like perspiration, from the surface of the membranes, and most likely is merely the watery portion of the blood exuded through. The uses of this fluid are various. As already stated, it probably supplies some nutriment to the fœtus, which it also protects, in a great measure, from pressure and from concussions. It also prevents the limbs from adhering, and helps to distend the mouth of the Womb, in the earlier stages of labor, besides affording an abundant slippery fluid for the purpose of lubricating the passages, thus making the passage of the child more easy.—(See Plate [XII].)

The other two membranes, the Chorion and Decidua, are not of much importance in our present explanation; and practically, in fact, the whole three may be regarded as one envelope, surrounding the child and the waters in which it floats.

THE PLACENTA.

At the full term the Placenta, (See Plate [XII],) is about six or seven inches in diameter, and nearly circular, though often irregular. Its thickness varies from one to two inches, and is greatest where the cord is inserted. Sometimes it is very large, or very thick, and may then be difficult to extract, and even cause serious accidents.

As already explained the Placenta is composed of a mass of blood-vessels, by means of which the blood of the fœtus is, in some way, brought into contact, or commingled with that of the mother. Its uterine face is irregular, being broken into lobes, or cotyledons, on which may be seen a vast number of little veins and arteries, corresponding with others on the inner surface of the Womb. Its outer surface is of a grey red color, and covered with the fœtal membranes, under which the large blood-vessels can be traced. The Placenta is usually attached to one side of the Uterus, near the fundus, or at the fundus, but sometimes it grows wholly, or in part, over the mouth of the Womb; an occurrence which may cause serious consequences.

When there is more than one child each usually has a separate placenta, and they are all intimately connected. In some rare cases however, one placenta only exists with twins. Each child has also a separate amnion, and waters; but there may be only one chorion and decidua for the whole, or each may have a complete set of membranes itself. Instances have been known however, of two children being enclosed in the same amnion, and surrounded by the same waters, having but one placenta between them.

These possible diversities show the accoucheur how necessary it is for him, in any case of multiple pregnancy, to be sure that he has abstracted all the after birth; and they also caution him not to proceed to unnecessary manipulations merely because it is not the same as in other cases.

THE UMBILICAL CORD.

This is composed, as already stated, of an artery and two veins, which twist round the artery, like the strands of a rope. These are all enclosed in a sheath, and surrounded by a thick kind of mucus, called the Gelatine of Wharton. Its thickness is about that of the little finger, though it may be much larger, having been seen as thick as the child's body. Its usual length is about eighteen or twenty inches, but it has measured as much as five feet. Then again it has been found so small that the vessels in it could not nourish the child. These exceptional variations however, are very rare. The veins may also be enlarged, or full of knots, and the circulation may be so much impeded thereby as to cause abortion. The various accidents which may result from anomalies in the cord will however, engage our attention in another place.