sacrum is that the transverse (T) diameter of the pelvic brim is shorter instead of longer than the antero-posterior (c. v). The sides of the pelvis have a tendency to parallelism, as well as the antero-posterior walls; and this is stated by Wood to be a peculiar characteristic of the infantile pelvis. The iliac bones are not spread out as in adult life, so that the centres of the crests of the ilia are not more distant from each other than the anterior superior spines. The cavity of the true pelvis is small, and the tuberosities of the ischia are proportionately nearer to each other than they afterward become; the pelvic viscera are consequently crowded up into the abdominal cavity, which is, for this reason, much more prominent in children than in adults. The bones are soft and semi-cartilaginous until after the period of puberty, and yield readily to the mechanical influences to which they are subjected; and the three divisions of the innominate bone remain separate until about the twentieth year.

As the child grows older the transverse development of the sacrum increases, and the pelvis begins to assume more and more of the adult shape. The mere growth of the bones, however, is not sufficient to account for the change in the shape of the pelvis, and it has been well shown by Duncan that this is chiefly produced by the pressure to which the bones are subjected during early life. The iliac bones are acted upon by two principal and opposing forces. One is the weight of the body above, which acts vertically upon the sacral extremity of the iliac beam through the strong posterior sacro-iliac ligaments, and tends to throw the lower or acetabular ends of the sacro-cotyloid beams outward. This outward displacement, however, is resisted, partly by the junction between the two acetabular ends at the front of the pelvis, but chiefly by the opposing force, which is the upward pressure of the lower extremities through the femurs. The result of these counteracting forces is that the still soft bones bend near their junction with the sacrum, and thus the greater transverse development of the pelvic brim characteristic of adult life is established. In treating of pelvic

deformities it will be seen that the same forces applied to diseased and softened bones explain the peculiarities of form that they assume.

Pelvis in Different Races.-The researches that have been made on the differences of the pelvis in different races prove that these are not so great as might have been expected. Joulin pointed out that in all human pelves the transverse (T) diameter was larger than the antero-posterior (c. v), while the reverse was the case in all the lower animals, even in the highest simiæ. This observation has been more recently confirmed by Von Franque,' who has made careful measurements of the pelvis in various races. In the pelvis of the gorilla the oval form of the brim, resulting from the increased length of the conjugate (c. v) diameter, is very marked. In certain races there is so far a tendency to animality of type that the difference between the transverse (T) and conjugate (c. v) diameters is much less than in European women, but it is not sufficiently marked to enable us to refer any given pelvis to a particular race. Von Franque makes the general observation that the size of the pelvis increases from south to north, but that the conjugate (c. v) diameter increases in proportion to the transverse (T) in southern races.

Soft Parts in Connection with Pelvis.-In closing the description of the pelvis, the attention of the student must be directed to the muscular and other structures which cover it. It has already been pointed out that the measurements of the pelvic diameters are considerably lessened by the soft parts, which also influence parturition in other ways. Thus, attached to the crests of the ilia are strong muscles which not only support the enlarged uterus during pregnancy, but are powerful accessory muscles in labor: in the pelvic cavity are the obturator and pyriformis muscles lining it on either side; the pelvic cellular tissue and fasciæ; the rectum and bladder; the vessels and nerves, pressure on which often gives rise to cramps and pains during pregnancy and labor; while below, the outlet of the pelvis is closed, and its axis directed forward by the numerous muscles forming the floor of the pelvis and perineum. The structures closing the pelvis have been accurately described by Dr. Berry Hart, who points out that they form a complete diaphragm stretching from the pubis to the sacrum, in which are three " faults" or "slits" formed by the orifices of the urethra, vagina, and rectum. The first of these is a mere capillary slit, the last is closed by a strong muscular sphincter, while the vagina, in a healthy condition, is also a mere slit, with its walls in accurate apposition. Hence it follows that none of these apertures impairs the structural efficiency of the pelvic floor, or the support it gives to the structures above it.

Scanzoni's Beiträge, 1867.

The Structural Anatomy of the Female Pelvic Floor.

CHAPTER II.

THE FEMALE GENERATIVE ORGANS.

THE reproductive organs in the female are conveniently divided, according to their function, into: 1. The external or copulative organs, which are chiefly concerned in the act of insemination, and are only of secondary importance in parturition: they include all the organs situate externally which form the vulva; and the vagina, which is placed internally and forms the canal of communication between the uterus and the vulva. 2. The internal or formative organs: they include the ovaries, which are the most important of all, as being those in which the ovule is formed; the Fallopian tubes, through which the ovule is carried to the uterus; and the uterus, in which the impregnated ovule is lodged and developed.

1. The external organs consist of:

The mons Veneris (Fig. 14, F), a cushion of adipose and fibrous tissue which forms a rounded projection at the upper part of the vulva. It is in relation above with the lower part of the hypogastric region, from which it is often separated by a furrow, and below it is continuous with the labia majora on either side. It lies over the symphysis and horizontal rami of the pubes. After puberty it is covered with hair. On its integument are found the openings of numerous sweat and sebaceous glands.

The labia majora (Fig. 14, a) form two symmetrical sides to the longitudinal aperture of the vulva. They have two surfaces, one external, of ordinary integument, covered with hair, and another internal, of smooth mucous membrane, in apposition with the corresponding portion of the opposite labium, and separated from the external surface by a free convex border. They are thicker in front, where they run into the mons Veneris, and thinner behind, where they are united, in front of the perineum, by a thin fold of integument called the fourchette, which is almost invariably ruptured in the first labor. In the virgin the labia are closely in apposition, and conceal the rest of the generative organs. After childbearing they become more or less separated from each other, and in the aged they waste, and the internal nymphæ protrude through them. Both their cutaneous and mucous surfaces contain a large number of sebaceous glands, opening either directly on the surface or into the hair follicles. In structure the labia are composed of connective tissue, containing a varying amount of fat, and parallel with their external surface are placed tolerably close plexuses of elastic tissue, interspersed with regularly arranged smooth muscular fibres. These fibres are described by Broca as forming a membranous sac, resembling the dartos of the scrotum, to which the labia majora are analogous. Toward its upper

and narrower end this sac is continuous with the external inguinal ring, and in it terminate some of the fibres of the round ligament. The analogy with the scrotum is further borne out by the occasional hernial protrusion of the ovary into the labium, corresponding to the normal descent of the testis in the male.

External genitals of virgin with diaphragmatic hymen. a. Labium majus. b. Labium minus. c. Præputium clitoridis. d. Glans clitoridis. e. Vestibule just above urethral orifice. F. Mons Veneris. (After SAPPEY.)

The labia minora, or nymphæ (Fig. 14, b), are two folds of mucous membrane, commencing below, on either side, about the centre of the internal surface of the labium externum; they converge as they proceed upward, bifurcating as they approach each other. The lower branch of this bifurcation is attached to the clitoris (Fig. 14, d), while the upper and larger unites with its fellow of the opposite side, and forms a fold round the clitoris, known as its prepuce, c. The nymphæ are usually entirely concealed by the labia majora, but after childbearing and in old age they project somewhat beyond them; then they lose their delicate pink color and soft texture, and become brown, dry, and like skin in appearance. This is especially the case in some of the negro races, in whom they form long projecting folds called the

apron.

The surfaces of the nymphæ are covered with tessellated epithelium, and over them are distributed a large number of vascular papillæ, somewhat enlarged at their extremities, and sebaceous glands, which are more numerous on their internal surfaces. The latter secrete an odorous, cheesy matter, which lubricates the surface of the vulva, and prevents its folds adhering to each other. The nymphæ are composed of trabeculæ of connective tissue, containing muscular fibres.

The clitoris (Fig. 14, d) is a small erectile tubercle situated about half an inch below the anterior commissure of the labia majora. It is the analogue of the penis in the male, and is similar to it in structure, consisting of two corpora cavernosa, separated from each other by a fibrous septum. The crura are covered by the ischio-cavernous muscles, which serve the same purpose as in the male. It has also a suspensory ligament. The corpora cavernosa are composed of a vascular plexus with numerous traversing muscular fibres. The arteries are derived from the internal pudic artery, which gives a branch, the cavernous, to each half of the organ; there is also a dorsal artery distributed to the prepuce. According to Gussenbauer, these cavernous arteries pour their blood directly into large veins, and a finer venous plexus near the surface receives arterial blood from small arterial branches. By these arrangements the erection of the organ which takes place during sexual excitement is favored. The nervous supply of the clitoris is large, being derived from the internal pudic nerve, which supplies branches to the corpora cavernosa, and terminates in the glans and prepuce, where Paccinian corpuscles and terminal bulbs are to be found. On this account the clitoris has been supposed by some to be the chief seat of voluptuous sensation in the female.

The vestibule (Fig. 14, e) is a triangular space, bounded at its apex by the clitoris, and on either side by the folds of the nymphæ. It is smooth, and, unlike the rest of the vulva, is destitute of sebaceous glands, although there are several groups of muciparous glands opening on its surface. At the centre of the base of the triangle, which is formed by the upper edge of the opening of the vagina, is a prominence, distant about an inch from the clitoris, on which is the orifice of the urethra. This prominence can be readily made out by the finger, and the depression upon it-leading to the urethra-is of importance as our guide in passing the female catheter. This little operation ought to be performed without exposing the patient, and it is done in several ways. The easiest is to place the tip of the index finger of the left hand (the patient lying on her back) on the apex of the vestibule, and slip it gently down until we feel the bulb of the urethra, and the dimple of its orifice, which is generally readily found. If there is any difficulty in finding the orifice, it is well to remember that it is placed immediately below the sharp edge of the lower border of the symphysis pubis, which will guide us to it. The catheter (and a male elastic catheter is always the best, especially during labor, when the urethra is apt to be stretched) is then passed under the thigh of the patient, and directed to the orifice of the urethra by the finger of the left hand, which is placed upon it. We must be careful that the instrument is really passed into the urethra, and not into the vagina.