VAGINA. UTERUS. 607 



near the uterus becomes dilated ; and is closed by the contact of the 

 anterior with the posterior wall. Its length is variable ; but it is 

 always longer upon the posterior than upon the anterior wall, the 

 former being usually about five or six inches in length, and the latter 

 four or five. It is attached to the cervix of the uterus, which latter 

 projects into the upper extremity of the canal. 



In Structure the vagina is composed of a mucous lining, a layer of 

 erectile tissue, and an external tunic of contractile fibrous tissue, re- 

 sembling the dartos of the scrotum. The upper fourth of the posterior 

 wall of the vagina is covered, on its pelvic surface, by the peritoneum ; 

 while in front the peritoneum is reflected from the upper part of the 

 cervix of the uterus to the posterior surface of the bladder. On each 

 side it gives attachment superiorly to the broad ligaments of the 

 uterus ; and inferiorly to the pelvic fascia and levatores ani. 



The Mucous membrane presents a number of transverse papilla or 

 rugce upon its upper and lower surfaces, which extend outwards on 

 each side from a middle raphe. The transverse papilla and raphe are 

 more apparent upon the upper than upon the lower surface, and the 

 two raphe are called the columns of the vagina. The mucous mem- 

 brane is covered by a thin cuticular epithelium, which is continued 

 from the labia, and terminates by a fringed border at about the middle 

 of the cervix uteri. 



The Middle or erectile layer consists of erectile tissue enclosed be- 

 tween two layers of fibrous membrane ; this layer is thickest near the 

 commencement of the vagina, and becomes gradually thinner as it 

 approaches the uterus. 



The External, or dartoid layer of the vagina, serves to connect it to 

 the surrounding viscera. Thus, it is very closely adherent to the 

 under surface of the bladder, and drags that organ down with it in 

 prolapsus uteri. To the rectum it is less closely connected, and that 

 intestine is therefore less frequently affected in prolapsus. 



The Uterus is a flattened organ of a pyriform shape, having the base 

 directed upwards and forwards, and the apex downwards and back- 

 wards in the line of the axis of the inlet of the pelvis, and forming a 

 considerable angle with the course of the vagina. It is convex on its 

 posterior surface, and somewhat flattened upon its anterior aspect. In 

 the unimpregnated state it is about three inches in length, two in 

 breadth across its broadest part, and one in thickness, and is divided 

 into fundus, body, cervix, and os uteri. At the period of puberty the 

 uterus weighs about one ounce and a half ; after parturition from two 

 to three ounces ; and at the ninth month of utero-gestation from two 

 to four pounds. 



The Fundus and body are enclosed in a duplicature of peritoneum, 

 which is connected with the two sides of the pelvis, and forms a trans- 



