THE VISCERA. 239 



which, however, when the bladder is empty, is separated from it by the 

 peritoneum. At the sides of the basis are situated : uniting tissue, and Mm. 

 levatores ani. b. In the female : firmly on and above the Vagina, and loosely 

 on the inferior half of collum uteri. 



5. The superior wall, vertex, apex, is directed forwards and upwards, and 

 covered by the peritonteum. In an upright position the intestines rest upon 

 it. In front the urachus s. /.>. suspensorium passes off from it, ascending to 

 the umbilicus. This mom' T.I .ous cord is the remains of a canal which, even 

 in the human embryo (in those of quadrupeds it is certain) up to the fourth 

 month, is said to pass through by the umbilical cord into the allantois. Com- 

 pare the history of development. 



6. The neck of the bladder, collum vesica, in the narrow part of the bladder, 

 at the most inferior region of the anterior vesical wall, which in the male is 

 surrounded by the prostate, and lies close behind the inferior border of the 

 symphys. pubis (in the female above the vagina). 



Structure of the urinary bladder: 1. Mucous membrane, whitish and thin, 

 with a few mucous follicles (in the neighbourhood of the neck) ; strong 

 and sensitive, presents numerous folds, which disappear upon extension of 

 the bladder, and a columnar or network appearance, according as the fibres 

 of the muscular tunic project. Besides, the openings of the two ureters and 

 the urethra, between which arises a smooth triangle, corpus trigonum, bounded 

 by two slight folds, plicee uretericte, which are situated behind the neck of the 

 bladder, and before the fundus vesica, frequently forming a pouch on either 

 side (sinus vesical.). 



2. The muscular coat invests the mucous membrane, with which it is 

 united by a thin layer of uniting tissue (tunica propria) is externally thin, 

 and consists of 



a. An external layer of longitudinal fibres, which ascend from the 

 neck of the bladder on the anterior and posterior wall to the vertex, and 

 pass as m. detrusor urina. 



b. An internal layer, which consists partly of regular or irregular cir- 

 cular fibres crossing each other (the first at the fundus, the last particu- 

 larly on the posterior wall), partly of fibres passing obliquely. 



M. Sphincter Vesica is just such a fasciculus of circular fibres, which 

 closes the orifice of the urethra into the bladder. 



3. The peritoneum covers the vertex and the posterior surface of the bladder 

 only ; reaches in the male (excavat. rectovesical.') deeper downwards than in 

 the female (excav. vesico-uterina). 



Vessels: Artt. vesicates, from the hypogastrica and its branches. Veins form 

 plexus vesical. about the neck of the bladder, and open into V. hypogastric. 

 Lymphatics : they mostly lie between peritoneum and the muscular coat, and 

 pass into plex. hypogastric. Nerves : branches of plexus hypogastriciis lateralis 

 and sacralis (voluntary and involuntary). 



Function of the bladder: to hold the urine which continually 

 and guttatim flows in through the ureters, and when contained in 

 sufficient quantity, the resistance of the sphincter vesic. is over- 

 come, and it flows out. 



