SPLANCHNOLOGY 



large size, and correspond with the arteries. They end in the uterine plexuses. In the impreg- 

 nated uterus the arteries carry the blood to, and the veins convey it away from, the intervillous 

 space of the placenta (see page 63). The lymphatics are described on page 714. The nerves 

 are derived from the hypogastric and ovarian plexuses, and from the third and fourth sacral 

 nerves. 



The Vagina (Fig. 1166). 



The vagina extends from the vestibule to the uterus, and is situated behind the 

 bladder and in front of the rectum; it is directed upward and backward, its axis 

 forming with that of the uterus an angle of over 90, opening forward. Its walls 

 are ordinarily in contact, and the usual shape of its lower part on transverse section 

 is that of an H, the transverse limb being slightly curved forward or backward, 

 while the lateral limbs are somewhat convex toward the median line; its middle 

 part has the appearance of a transverse slit. Its length is 6 to 7.5 cm. along its 

 anterior wall, and 9 cm. along its posterior wall. It is constricted at its commence- 

 ment, dilated in the middle, and narrowed near its uterine extremity ; it surrounds 

 the vaginal portion of the cervix uteri, a short distance from the external orifice 

 of the uterus, its attachment extending higher up on the posterior than on the 

 anterior wall of the uterus. To the recess behind the cervix the term posterior 

 fornix is applied, while the smaller recesses in front and at the sides are called the 

 anterior and lateral fornices. 



Relations. The anterior surface of the vagina is in relation with the fundus of the bladder, 

 and with the urethra. Its posterior surface is separated from the rectum by the rectouterine 

 excavation in its upper fourth, and by the rectovesical fascia in its middle two-fourths; the lower 

 fourth is separated from the anal canal by the perineal body. Its sides are enclosed between 

 the Levatores ani muscles. As the terminal portions of the ureters pass forward and medial- 

 ward to reach the fundus of the bladder, they run close to the lateral fornices of the vagina, and 

 as they enter the bladder are slightly in front of the anterior fornix. 



Structure. The vagina consists of an internal mucous lining and a muscular coat separated 

 by a layer of erectile tissue. 



The mucous membrane (tunica mucosa) is continuous above with that lining the uterus. Its 

 inner surface presents two longitudinal ridges, one on its anterior and one on its posterior wall. 

 These ridges are called the columns of the vagina and from them numerous transverse ridges 

 or rugse extend outward on either side. These rugae are divided by furrows of variable depth, 

 giving to the mucous membrane the appearance of being studded over with conical projections 

 or papillae; they are most numerous near the orifice of the vagina, especially before parturition. 

 The epithelium covering the mucous membrane is of the stratified squamous variety. The sub- 

 mucous tissue is very loose, and contains numerous large veins which by their anastomoses form 

 a plexus, together with smooth muscular fibers derived from the muscular coat; it is regarded 

 by Gussenbauer as an erectile tissue. It contains a number of mucous crypts, but no true glands. 



The muscular coat (tunica muscularis) consists of two layers: an external longitudinal, which 

 is by far the stronger, and an internal circular layer. The longitudinal fibers are continuous 

 with the superficial muscular fibers of the uterus. The strongest fasciculi are those attached 

 to the rectovesical fascia on either side. The two layers are not distinctly separable from each 

 other, but are connected by oblique decussating fasciculi, which pass from the one layer to the 

 other. In addition to this, the vagina at its lower end is surrounded by a band of striped muscular 

 fibers,- the Bulbocavernosus (see page 430). 



External to the muscular coat is a layer of connective tissue, containing a large plexus of 

 bloodvessels. 



The erectile tissue consists of a layer of loose connective tissue, situated between the mucous 

 membrane and the muscular coat; imbedded in it is a plexus of large veins, and numerous bundles 

 of unstriped muscular fibers, derived from the circular muscular layer. The arrangement of the 

 veins is similar to that found in other erectile tissues. 



The External Genital Organs (Partes Genitales Externae Muliebres) 



(Fig. 1171). 



The external genital organs of the female are: the mons pubis, the labia majora 

 et minora pudendi, the clitoris, the vestibule of the vagina, the bulb of the vestibule, 

 and the greater vestibular glands. The term pudendum or vulva, as generally applied, 

 includes all these parts. 







