1028 THE FEMALE ORGANS OF GENERATION. 



Relations. Its anterior surface is in relation with the base of the bladder and 

 with the urethra. Its posterior surface is connected for the lower three-fourths of 

 its extent to .the anterior wall of the rectum, the upper fourth being separated from 

 that tube by the recto-vaginal pouch of peritoneum, or pouch of Douglas, between 

 the vagina and rectum. Its sides are enclosed between the Levatores ani muscles. 



Structure. The vagina consists of an internal mucous lining, of a muscular 

 coat, and between the two of a layer of erectile tissue. 



The mucous membrane is continuous above with that lining the uterus. Its 

 inner surface presents, along the anterior and posterior walls, a longitudinal ridge 

 or raphe', called the columns of the vagina, and numerous transverse ridges or 

 rugae, extending outward from the raphe' on either side. These rugse 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 in females before parturition. The epi- 

 thelium covering the mucous membrane is of the 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 fibres 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 consists of two layers : an external longitudinal, which is 

 far the stronger, and an internal circular layer. The longitudinal fibres are 

 continuous with the superficial muscular fibres of the uterus. The strongest 

 fasciculi are those attached to the recto-vesical fascia on each side. The two layers 

 are not distinctly separable from each other, but are connected by oblique decus- 

 sating 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 fibres, the 

 sphincter vagina; (see page 375). 



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

 large plexus of blood-vessels. 



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 fibres derived from the circular 

 muscular layer. The arrangement of the veins is similar to that found in other 

 erectile tissues. 



THE UTEEUS. 



The Uterus is the organ of gestation, receiving the fecundated ovum in its cavity, 

 retaining and supporting it during the development of the foetus, and becoming 

 the principal agent in its expulsion at the time of parturition. 



In the virgin state it is pear-shaped, flattened from before backward, and 

 situated in the cavity of the pelvis between the bladder and the rectum ; it is 

 retained in its position by the round and broad ligaments on each side, and projects 

 into the upper end of the vagina below. Its upper end, or base, is directed 

 upward and forward; its lower end, or apex, downward and backward, in the 

 line of the axis of the inlet of the pelvis. It therefore forms an angle with the 

 vagina, since the direction of the vagina corresponds to the axis of the cavity and 

 outlet of the pelvis. The uterus measures about three inches in length, two in 

 breadth at its upper part, and nearly an inch in thickness, and it weighs from an 

 ounce to an ounce and a half. 



It consists of two parts : (1) the body, with its upper broad extremity, the 

 fundus ; and (2) the cervix, or neck, which is partly above the vagina and partly 

 in the vagina. The fundus is placed on a line below the level of the brim of the 

 pelvis, and its direction varies with the condition of the bladder. 



The division between the body and cervix is indicated externally by a slight 

 constriction, and by the reflection of the peritoneum from the anterior surface of 

 the uterus on to the bladder, and internally by a narrowing of the canal, called 

 the internal os. 



