113 UROGENITAL SYSTEM. 
Douglas. Lower down, the posterior wall les close against the rectum, from which 
it is separated by a layer of the pelvic fascia. As, however, the orifice of the vagina 
is approached, the rectum and vagina become separated by a considerable interval, 
which is occupied by a mass of fibrous and fatty tissue, often called the “ perineum ” 
x “perineal body.” At the sides the vagina is supported by the levatores ani 
chee The terminal part of the ureter lies not far from the side wall of the 
upper part of the vagina, as it passes from above and behind downwards, inwards, 
and a little forwards to reach the bladder. Near its termination the vagina pierces 
the triangular ligament, and is related laterally to the bulbus vestibuli, the gland 
of Bartholin, and the sphincter vaginze muscle. 
Structure of the Vagina.—The vaginal wall has a distinct muscular coat (tunica 
muscularis), composed of unstriped muscle fibres, most of which are longitudinally dis- 
posed. Towards the lower end of the passage circularly-disposed striped muscle fibres are 
found in the deeper part of the muscular coat. The thick mucous membrane (tunica 
mucosa), which has a stratified scaly epithelium, is corrugated, and presents a number of 
transverse ridges or elevations called ruge vaginales. In addition to these transverse 
rugee, a slightly marked longitudinal ridge, or column, is to be seen on the anterior and 
on the posterior wall of the vagina. These receive the name columne rugarum, and, like 
the transverse ruge, are best seen in young subjects, and in the lower part of the vagina. 
The urethral canal lies in close relationship to the anterior column of the vagina in its 
lower part, and hence this portion of the anterior column is sometimes called the 
carina urethralis (Figs. 746, B and 776). 
Within the mucous coat are to be found small collections, or nodules, of lymphoid 
tissue. 
The vaginal wall is surrounded by a layer of loose vascular connective tissue contain- 
ing numerous large communicating veins. 
Variation.—In rare cases the vagina has been found divided by an incomplete septum into 
two passages. Such abnormality is due to an incomplete fusion of the lower portions of the 
Miillerian ducts from which the vagina is developed in the embryo. 
Vessels and Nerves of the Vagina. —The blood supply of the vagina is for the most part 
derived from branches of the vesico-vaginal artery, the vaginal branch ‘of the uterine artery, the 
vaginal branches of the middle hemorrhoidal artery, and fr om the branches of the internal pudic. 
The veins form a plexus surrounding the vaginal wall, and drain their blood into the tributaries 
of the internal iliac. The lymphatics from the upper part of the vagina join the internal iliac 
group of glands, while those from the lower part end in the superficial inguinal glands. The 
nerves of the \ vagina are derived from the plexus utero-vaginalis, and from the plexus vesicalis. 
Other fibres are derived directly from the third and fourth sacral nerves. 
THE FEMALE EXTERNAL GENITAL ORGANS. 
The term vulva, or pudendum (pudendum muliebere), is often applied collec- 
tively to the female external genital organs, 7.e. to the libia majora and the struc- 
bures which lie between them. 
Labia Majora.—The labia majora represent the scrotum in the male, and 
form the largest part of the female external genital organs. They form the lateral 
boundaries of the urogenital cleft (rima pudendi), into which the urethra and 
vagina open. Each labium is a prominent rounded fold of skin, narrow behind 
where it approaches the anus, but increasing in size as 1t passes forwards and up- 
wards to end in a median elevation, nee mons pubis or Veneris. The mons 
Veneris, also called the anterior commissure (commissura labiorum anterior), lies 
over the symphysis pubis, and, like the labia majora, it is composed chiefly of fatty 
and areolar tissue, and is covered by hair. The outer convex surface of each 
labium majus is covered by skin resembling that of the scrotum in the male, but 
the inner flatter surface is smooth, and presents a more delicate integumentary 
covering. In some cases the posterior narrow ends of the labia majora are con- 
nected across the middle line in front of the anus by a slight transverse fold—the 
posterior commissure (commissura labiorum posterior). 
Usually, especially in young subjects, the labia majora are the only visible parts 
of the external genital organs, since they are in contact with one another, and 
completely enclose the structures within the urogenital cleft. 
