THE SOFT PARTS OP THE GENITAL PASSAGE 57 



The urinary bladder rests upon the floor of the pelvis. 

 When emptied, it lies on the more elevated portion of the 

 pelvic floor ; when filled, it reaches up to, or even bejond, the 

 anterior pubic border. It usually does not interfere with the 

 passage of the foetus either during eutokia or dystokia, being 

 mostly emptied in the preparatory period. 



The reflectory contractions of the muscularis of the 

 rectum and detrusor muscle of the bladder are of physio- 

 logical importance in preparing the genital passage. 



The internal wall of the genital passage is principally 

 formed by the vagina and vestibule. Since they fill the pelvic 

 cavity, the abdominal cavity is practically closed by them. In 

 speaking of the uterus, it was stated that its attachment 

 depends on two folds of the peritoneum, termed mesometrium. 

 (Fig. l.j 



From the upper face of the uterus the peritoneum runs 

 posteriorly to the vagina, turns upward and forward, to end in 

 the serous lining of the rectum. The peritoneal fold thus 

 formed has a space between its two layers communicating with 

 the abdominal cavity, known as the recto-uterine or recto-vaginal 

 excavation. That part of the mesometrium, respectively peri- 

 toneum, lining the lower face of the womb, runs also toward 

 the vagina, about to the meatus urinarius, turning then down- 

 ward and forward, covering the upper face of the urinary 

 bladder. These vesico-vagiual folds enclose a space also con- 

 necting with the abdominal cavity, and termed the vesico- 

 uterine excavation. 



Both excavations play an important role in the aetiology 

 of the prolapsus vagiuse and prolapsus vesicae. This shows 

 that only the anterior part of the vagina has a serous covering ; 

 its outer line posteriorly is an adventitia, composed of con- 

 nective tissue and elastic fibres. This adventitia connects 

 above the vagina with the rectum and below with the visceral 

 layer of the pelvic fascia. Laterally, tlie adventitia joins the 

 coccygeal muscles and pelvic fascia. 



The vagina is least elastic where it becomes the "vestibule, 

 as certain muscles of that region end in a fibrous layer, 



