238 SPECIAL ANATOMY. 



downwards, forwards, and lastly inwards, where, arriving at the sides of the 

 fundus vesicce, it passes in this for about ten lines between the muscular and 

 mucous coats, and opens with a narrow mouth into the cavity of the urinary 

 bladder, at the posterior angle of Corp. trigonum. Position : as far as to Basis 

 oss. sacri, along the anterior border of m. psoas ; behind the peritoneum and 

 Va-sa Spermatica (which cross obliquely with it) ; the right ureter (extern- 

 ally) close to V. cava inferior. At the basis oss. sacri the ureter crosses the 

 vasa lliaca (forwards and inwards); in the small pelvis: with Art. umbili- 

 calis, vasa obturatoria, Vas deferens (in the male) ; the superior and lateral 

 parts of the vagina (in the female). When within the bladder it lies behind 

 Collum uteri (hence retention of urine at child-birth, &c.). 



Structure of the excretory ducts. 1. The mucous membrane is white, 

 smooth, and in folds, without valves, covered with pavement epithelium. 

 2. The middle coat, tunica propria. 3. The external coat is thick, consists 

 of smooth muscular tissue, the circular fibres of which as in all excretory 

 ducts of glands) form the external, the longitudinal fibres, the internal .thicker 

 layer. 



472. 3. The urinary bladder, vesica urinaria s. cystis, 



is a membranous, roundish sac (in the foetus pointed above), which 

 is situated in the cavity of the small pelvis close behind the bones 

 of the pubes, and is for the purpose of holding the urine. It is 

 held in its situation by fascia pelvis, and peritonseum ; Hgg. vesi- 

 calia lateralia (the obliterated artt. um.bilicales) and -medium 

 (the obliterated urachus) ; ligg. pubo-vesicalia (3) from the sym- 

 physis to the neck of the bladder in the female, or ligg. pubo- 

 prostatica in the male. The capacity of the bladder is different 

 according to the habits of individuals, &c., before birth propor- 

 tionably larger than afterwards, in the female likewise larger than 

 in the male, where it holds from 7 to 14 ounces of fluid. Direc- 

 tion of the axis : from above and before downwards and back- 

 wards. 



Divisions : the top, vertex, is the superior, smallest ; body, 

 corpus, the central; basis, fundus, is the most inferior and broad- 

 est part of the bladder. 



The external convex surface presents the following parts : 



1. The anterior wall is situated close behind the symphysis, corp. oss. pubis, 

 and mm. obturat. intern., with loose, uniting tissue only interspersed, and with- 

 out peritoneum ; in the female (because the prostate is wanting), rather under 

 the Symphysis and above it, close behind the abdominal walls, when the 

 bladder is distended. 



2. The posterior wall, quite covered by peritonaeum^ is situated before the 

 rectum (in the male) ; before the Uterus (in the female) ; nevertheless, small 

 intestines generally slip in between. 



3. The lateral parietes, covered by peritoneum, close to Art. umbilicales 

 (s. lig. lateralis), and Vasa deferentia (in the male). 



4. The inferior wall, basis, a. In the male : above the vesicute seminales 

 and Vasa deferentia, and the triangular piece of the rectum between them, 



