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they are united by intermediate cartilage, and thus retain so much mobility upon each other, as well as upon the lower end of the sacrum, as to admit of being forced backwards to the extent of a full inch, thus contributing greatly to increase the capacity of the outlet.

The sacrum not only serves to form the posterior parietes of the pelvis, but by the curve which its lower portion takes forwards, together with the coccyx, it gives a powerful support to the pelvic viscera.

When we take a general view of the bones which collectively form, the pelvis, we find that it is evidently divided into two portions-an upper and a lower one. On the Continent these have been called the large and the small pelvis; in Britain we merely speak of the pelvis above or below the brim, the line of demarkation being the linea ilio-pectinea at the sides, the crista of the os pubis in front, and the promontory of the sacrum behind. The alæ of the ilia form a prominent feature in the upper pelvis, and not only afford an attachment for numerous muscles, but furnish a powerful and ample means of protection and support to the pelvic and lower abdominal viscera. In the female pelvis this is remarkably the case, the cavitas iliaca being well expanded and of greater extent than in the male, the crista of the ilium thrown more outwards; hence the distance between the antero-superior processes is much more considerable.

Distinction between the male and female pelvis. At the brim, the female pelvis presents several well-marked points of distinction from that of the male. The male pelvis has a contracted brim of a rounded or rather triangular form, with the promontory of the sacrum considerably projecting; whereas, that of the female is spacious, of an oval shape, and with a slightly prominent sacrum, thus affording more room for the passage of the child through the brim. The cavity of the male pelvis is deep, while in the female pelvis it is shallow, a circumstance which is very strikingly seen in comparing the length of the symphysis pubis in each, that of the male pelvis being nearly double the length of the female. This is an important point of difference as regards parturition, because in a shallow pelvis, the extent of surface exposed to the pressure of the head will be much less than where it is deep, and hence the resistance to the passage of the child will be proportionably diminished: in confirmation of this, we find that tall women, in whom the pelvis is usually deep, do not, on the whole, bear children so easily as women of middling stature, in whom the pelvis is more shallow. The capacious hollow of the sacrum in the female pelvis adds also greatly to the extent of its cavity, and peculiarly adapts it for parturition, the injurious pressure of the head upon the soft linings of the pelvis being thus prevented, and every facility afforded for its quick and easy transit through the cavity. This applies especially to the neck of the bladder, which would almost inevitably suffer in every labour, were it not for the ample hollow of the sacrum relieving the pressure of the head against the anterior portions of the pelvis. The bones of the female pelvis being more slender and delicately formed, the foramina ovalia and sacro-ischiatic notches are wider, and thus add still farther to the capacity of the cavity.

In no part of the pelvis is the difference between the sexes more strongly marked than at the outlet. The spacious and well rounded arch of

the pubes, in the female, of the slender rami, is a striking contrast to the contracted angular arch of the male pelvis; and the tuberosities of the ischium being much wider apart, the head is enabled to pass under the arch with greater facility, and thus still farther to relieve the anterior of the pelvis from its pressure. The length of the sacro-sciatic ligaments, and the mobility of the coccyx upon the sacrum, by which it can be forced backwards to the extent of an inch by the pressure of the head during labour, not merely serve to distinguish it from the male pelvis, but afford a beautiful instance of design and adaptation.

The greater width of the pubic arch in the female pelvis is seen by comparing its angle with that of the arch in the male pelvis. In the female it has been estimated to form an angle varying between 90° and 100°, whereas in the male it is not more than between 70° and 80°. (Osiander, Handbuch der Embindungs-kunst, cap. iv. p. 58.)

From the greater width of the female pelvis, the acetabula are farther apart, and the great trochanters of the thigh-bones more projecting; hence the greater motion of the hips in the female when she walks, which is still more visible when she runs, for the motion is communicated to the whole trunk, so that each shoulder is turned more or less forwards as the corresponding foot is advanced. The thigh-bones, which are so far apart at their upper extremities, approach each other at the knees, contributing to produce that unsteady gait which is peculiar to the sex. "The woman," says Mr. John Bell, "even of the most beautiful form, walks with a delicacy and feebleness which we come to acknowledge as a beauty in the weaker sex." (Bell's Anat. vol. i.)

These characteristic marks of the female figure, upon which its beauty in great measure depends, are well seen in all great works of art, whether of sculpture or painting, "The ancients," as Mr. Abernethy has observed, "who had a clear and strong perception of whatever is beautiful or useful in the human figure, and who, perhaps, delicately exaggerated beauty to render it more striking, have represented Venus as measuring one-third more across the hips than the shoulders, whilst, in Apollo, they have reversed these measurements." (Physiological Lectures.)

Diameters of the pelvis. It is of the utmost importance to the obstetrician, that he should be thoroughly acquainted with the various dimensions of the female pelvis, for, without this, he can form no correct idea of the manner in which the presenting part of the child passes through its brim, cavity and outlet during labour; indeed, unless he be thoroughly versed in this necessary point of obstetric knowledge, he will remain in almost total ignorance of the whole mechanism of parturition, which must, in great measure, be looked upon as the basis of practical midwifery. The dimensions of the brim cavity and outlet of the pelvis may be given with sufficient correctness for all practical purposes, by measuring three of their diameters,-1. the straight, antero-posterior, or conjugate; 2. the transverse; and 3. the oblique. At the brim they are as follow:the straight diameter, drawn from the middle of the promontorium sacri to the upper edge of the symphysis pubis, 4-3 inches; the transverse diameter, from the middle of the linea ilio-pectinea of one ilium to that of the other, 5.4 inches; and the oblique diameter, from one sacro-iliac synchondrosis to the opposite acetabulum, 4.8 inches. The oblique di

ameters are called right and left, according to the sacro-iliac symphysis from which they are drawn.

In the cavity these dimensions vary more or less. The straight dia

[merged small][merged small][graphic]

In the annexed representation of the superior and inferior aspects of
the female pelvis are shown the three diameters of its brim and outlet;
those of the former in fig. 1, and those of the latter in fig. 2. The same
letters of reference are used in each figure to indicate the several di-
ameters; thus a p refers to the antero-posterior, t t to the transverse,
oo to the right oblique, and o" o' to the left oblique diameters.
In fig. 2, the coccyx is represented in situ.

meter, measured from the centre of the hollow of the sacrum to that of the symphysis pubis, is 4.8 inches; the transverse, from the point corre sponding to the lower margin of the acetabulum on one side to that of the other, 43; and the oblique, drawn from the centre of the free space formed by the sacro-ischiatic notch and ligaments on one side of the fo ramen ovale of the other, 5.2.

At the inferior aperture or outlet the alteration is still more remarkable. The straight diameter, from the point of the coccyx to the lower edge of the symphysis pubis, measures only 3.8 inches; but from the mobility of the coccyx enabling it to be pushed back during labour to the extent of a whole inch, it is capable of being extended to 4.8 inches. The transverse diameter from one tuberosity of the ischium to the other, measures 4.3 inches and the oblique, from the middle of the lower edge of the sacrosciatic ligament of one side, to the point of union between the ischium and descending ramus of the pubes on the other 4.8 inches.

Although these are the proportions of the brim cavity and outlet of the female pelvis in the skeleton state, their real dimensions during life, when the pelvis is thickly lined with muscular and other structures, are very different. The large masses of the psoas magnus and iliacus internus, besides other muscles of inferior size, contribute to alter materially the relations of the pelvic diameters to each other; hence we find that, so far from being the longest, the transverse diameter is one of the shortest, being little more than the antero-posterior. This holds good, especially during labour, because these muscles being thrown into powerful contrac tion, their bellies swell, and thus tend still farther to diminish its length. The oblique diameters are, in fact, the longest during life, because not only are the parietes of the pelvis at the brim covered by a very thin layer of soft tissues in these directions; but as the extremities of these diameters, in the cavity and outlet, correspond to free spaces which are merely filled up with soft yielding structure, it follows that their length can be somewhat increased when pressure is applied in these directions; the antero-posterior diameter of the outlet can alone be compared with

the oblique diameters in this respect, and then only when the coccyx is forced backwards to its full extent by the pressure of the head.

Pelvis before puberty. The proportions of the adult female pelvis are no longer what they were during childhood; before the age of puberty they resemble those of the male pelvis, the brim being contracted, and more or less triangular, and the antero-posterior diameter equalling or even exceeding the transverse. Indeed, at a still earlier period, it presents many points of resemblance even to the pelvis of animals; as, however, growth and development advance, and the various changes which constitute puberty take place, the transverse diameters of the brim, cavity, and outlet increase at the expense of the antero-posterior, until, at length, it has assumed the proper proportions of the adult female pelvis.

Axes. Of not less importance is it that the obstetrician should be thoroughly acquainted with the direction which the central line or axis of the entrance and outlet of the pelvis takes. The axis of the superior aperture has been considered to form with the horizon an angle varying between 50° and 60°; this was noticed long ago by Dr. Smellie: "When the body of a woman," says this valuable author, "is reclined backwards, or half sitting, half lying, the brim of the pelvis is horizontal; and an imaginary straight line, descending from the navel, would pass through the middle of the cavity; but in the last month of pregnancy such a line must take its rise from the middle space between the navel and scrobiculus cordis in order to pass through the same point of the pelvis." (Treatise of Midwifery, book i. chap. i. sect. 2.)

Inclination of the pelvis. The angle which the axis of the superior aperture of the pelvis forms with the horizon, when a woman is in the upright posture, necessarily marks what has been called the inclination of her pelvis, and varies, of course, in proportion to the angle which the above mentioned axis forms. In a tall woman of slender figure, where the different curves of the spinal columns are slight, the inclination of the pelvis is much less than in a short thick-set woman, where the spine is much more strongly curved. Where the inclination is slight, the hollow of the sacrum is generally small, and the vulva directed more forwards; where, on the other hand, the pelvis is much inclined, the hollow of the sacrum is generally observed to be deep, and the vulva directed more or less backwards. The axis of the lower aperture or outlet appears to depend, in great measure, on the curve which the lower part of the sacrum takes downwards and forwards; but, as a general rule, we think it will be found to form, more or less, a right angle with the axis of the brim. The greater the angle which the axis of the brim forms with the horizon, the less will be that which the axis of the outlet forms, and vice versa; or, in other words, the angle with the horizon which the axis of the one forms is inversely to that of the other.

The consideration of the various deviations, as to size and form, from the natural proportions which the female pelvis occasionally presents, belongs, more strictly speaking, to that species of faulty labour which arises from these conditions. We, therefore, refer to the fourth species of dystocia, viz. Dystocia Pelvica, where the different pelvic anormalities are described.

CHAPTER II.

FEMALE ORGANS OF GENERATION.

INTERNAL AND EXTERNAL.-OVARIA.-OVUM.-CORPUS LUTEUM.-FALLOPIAN TUBES.

UTERUS.-VAGINA.-HYMEN.-CLITORIS.-NYMPHE.-LAEIA.

THE female organs of generation have been usually classed by the English authors, under the two heads of internal and external; a similar arrangement has also been followed by the Continental writers, but with the advantage of usi distinctive terms which are more expressive of their peculiar functions, viz. the formative and copulative organs. Under the first are included the ovaria, Fallopian tubes, and uterus: under the second, the vagina and external parts. We propose to give a short description of these in the unimpregnated state, and then to describe the changes which they present during pregnancy, labour, and the puerperal Condition. In point of situation and arrangement they bear a considerable resemblance to the generative organs in the male, being situated at the lower portion of the trunk, and arranged in symmetrical order, so that they either occur in pairs, one on each side the median line of the body, or singly, being equally divided by it throughout their whole length. Although there is in many points considerable difference between the male and female organs, still there is sufficient resemblance to entitle them to be considered as being formed upon the same fundamental type, a resemblance which is seen still more strikingly in the earlier periods of fœtal life. They differ essentially from all the other organs of the system, being in activity during a portion of a woman's life only, and then only at intervals.

Ovaria. The ovaries are situated in the upper part of the cavity of the pelvis, one on each side, near to the uterus, to which they are merely attached by a ligament (the ligamentum ovarii) which is a portion of that duplicature of the peritoneum which connects the uterus to the pelvis, and is known by the name of ligamentum latum, or broad liga

ment.

They are of an oval figure; their anterior and posterior surface is convex, the superior margin is also convex, while their lower edge is straight, or somewhat concave: towards their inner and outer extremities they become thinner.

Their external surface in the virgin state is usually smooth, but in advanced age they become uneven and shrivelled; when fully developed they are about an inch and a half in length; their greatest breadth, which is at that portion of the ovary which is farthest from the uterus, is half an inch; their thickness is somewhat less.

The ovaries are supplied with blood by the spermatic arteries, which are of course considerably shorter in the female; they pass between the

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