labia minora are always in contact and require to be artificially separated in order to see their inner surfaces. The fossa navicularis only exists when artificially opened up. Therefore, to see the external genitals fully, the labia must be separated and the prepuce drawn back.

A line running as follows separates mucous membrane from skin. Starting from the base of the inner aspect of the right labium minus, it passes down beside the base of the outer aspect of the hymen, up along the base of the inner aspect of the left labium minus, in beneath the prepuce of the clitoris, and down to where it first started from.

The vulvar slit is vertical, and lies in the middle line between the labia majora and minora.

The vaginal orifice is transverse, only exists when artificially made, and is anatomically defined by the hymen which separates the external genitals from the internal genitals. The sharp line between skin and mucous membrane can be distinctly seen on the living woman. The labia minora are skin, thin and fine, and not mucous membrane as often alleged. The following measurements by Foster are useful for reference :

Meatus urinarius, 2-2.5 cm. from fourchette, in nulliparae; 2-3.1 cm., in women who have borne children.

The virginal vaginal orifice should have the appearances shown at figs. 1, 3, 4, and 5, and the free edge of the hymen should be intact. In a healthy woman who has experienced complete coitus, the hymen

Hymen of Virgin with Vertical Slit. (4) Hymen with oval opening. (1)

is torn or often only stretched. It admits two fingers without pain. In a woman who has borne full-time children, the vaginal orifice is always torn though the fourchette and all behind it may be intact. The

In

remains of the hymen are known as the carunculae myrtiformes. addition, the passage of the child's head may cause tears of the posterior vaginal wall, perineal body, or even anterior wall of rectum.

(2.) THE PELVIC FLOOR AND ORGANS RESTING ON IT
CONSIDERED AS A WHOLE.

The outlet of the bony female pelvis is filled in by what is generally described as the 'soft parts.' This term, however, should not be employed, as it is misleading, especially in scientific obstetrics. It is better named the pelvic floor or pelvic diaphragm.

The pelvic floor is a thick fleshy elastic layer, dovetailed in all round to the bony pelvic outlet (Fig. 6). It may be considered as an

Fig. 6.

Bony Pelvic outlet, with transverse line showing Rectal and Urethral Triangles (D. J. Cunningham). (Į)

irregularly-edged segment of a hollow sphere, with an outer skin aspect and an inner peritoneal one. On the outer skin aspect lie the external genitals already described. On the inner peritoneal surface, we have the organ known as the uterus, and its appendages the Fallopian tubes and ovaries. The vagina runs at an angle of 60° to the horizon from the vaginal orifice upwards to the mouth of the womb, as a transverse slit in the pelvic diaphragm. In front of the vagina lies the bladder, while behind it the rectum is placed; these structures, along with muscles, connective tissue, blood-vessels, nerves, and lymphatics, making up the pelvic diaphragm.

Figure 1 shows, accordingly, the pelvic floor seen from its convex, skin aspect; fig. 53 gives it and the organs resting on it as viewed from its concave, peritoneal side; while fig. 34 displays it as seen in vertical sagittal section.

(8.) THE PELVIS CONSIDERED IN DETAIL.

MUSCULATURE OF THE PELVIC FLOOR.

If a female cadaver be placed in the Lithotomy posture and a transverse line drawn just in front of the ischial tuberosities, the perineal region will be divided into a posterior rectal triangle and an anterior urethral one (Fig. 6). The former contains the anus, the latter the external genitals. By suitable incisions the skin and superficial fascia, fat, &c., can be removed around the anus, and the ischiorectal fossa defined. This is a small pyramidal cavity on each side of the rectum, bounded externally by the obturator internus muscle, internally by the levator ani. Its apex is formed by the junction of these muscles, while its base is partially closed in by the transversus perinei and the edge of the gluteus maximus muscle (Fig. 7). If the skin, superficial fascia, and anterior layer of the triangular ligament be now removed from the urethral triangle, the following muscles, &c., will be exposed (Fig. 7).

a is just above Transversus Perinei; b Base of Perineal body; e Bulbocavernosus; d lies on Levator Ani and in Ischiorectal Fossa; e Erector Clitoridis; f Bulb of Vagina; g Bartholinian Gland; Vestibule Glans Clitoridis. (4)

Perineal muscles.-On each side of the vaginal orifice three muscles lie, viz., the bulbocavernosus (fig. 8, b c), erector clitoridis or ischiocavernosus (fig. 8, e c), and trans

versus perinei (fig. 8, tp).

t.p.

e.o

The Bulbocavernosi consist of two muscular slips, b.c one on each side of the vaginal orifice, which spring behind from the perineal body and pass round the vaginal orifice, partially covering the bulb and the vagina (fig. 7, c). The anterior end of each slip splits into three portions, which end as follows:one passes to the under surface of the corpus cavernosum of the clitoris, a second goes to the posterior surface of the bulb, and a third blends with the mucous membrane between the clitoris and urethral orifice (Henle, v. Fig. 9).

Fig. 8.

a Symphysis Pubis, showing muscles in connection with Clitoris and Bulb. The Clitoris, c, e", is cut across near its point, and thrown down with the vestibulary mucous membrane (Henle).

e Erector Clitoridis; f Bulbocavornosus with its three insertions; d venous branch to Dorsal Vein of Clitoris. (4)

The Erector Clitoridis arises from the inside of the ischial tuberosity, and becomes inserted into back and sides of the crus clitoridis. (Fig. 9, e).

The Transversus Perinei arises from the ramus of the ischium and passes to the perineal body. It is difficult to define practically in dissection (fig. 7, a).

Now that these muscles are defined, we are in a position to localize more important structures.

The Bulbi Vagina (corpora cavernosa uretræ) are small masses of erectile tissue about the size of a bean, lying one on each side of the vaginal orifice and partly under cover of the bulbo-cavernosus muscle. Each rests posteriorly on the triangular ligament, internally on the mucous membrane of the vagina; while, as already said, they are partly covered superiorly by the bulbo-cavernosus muscle. Anteriorly each blends with its fellow, and this pars intermedia becomes continuous with the clitoris (fig. 7, f).

The Bartholinian Glands lie one on each side of the vaginal orifice, close to the posterior end of the bulb and behind the anterior layer of the triangular ligament (figs. 7, g, and 10, e). Each has a long duct opening into the fossa navicularis.

Oblique Section, parallel to the Anterior Pelvic Wall and through the External Genitals (Henle). a Vagina; Urethra; e Corpus Cavernosum Clitoridis, covered by its Erector; d Bulbus Vaginae, covered by Bulbocavernosus Muscle; e Bartholinian Gland.

Between the lower one-third of the posterior wall of the vagina and the anterior wall of the rectum is an angular interspace (fig. 2, b) filled up by the structure known as the perineal body. This will be more fully described afterwards. At the present stage of the dissection only its base is seen, with the following muscles taking origin from or having an insertion into it,-sphincter ani, transversus perinei, bulbocavernosus, levator ani (fig. 7).

Between the layers of the triangular ligament lie the urethra, a portion of the vagina, compressor urethrae, dorsal vein of the clitoris, internal