ABDOMEN AND PELVIS 537 



Compare the general structure of the rectum with that of the 

 colon, noting any differences. 



Urinary Bladder (Vesica urinaria). (Vide Spalteholz, Figs. 640- 



642.) 



Distend the bladder with air by a bicycle-pump before the 

 dissection of its wall is made. Study the layers. 



(a) Serous tunic (tunica serosa). 



(aa) Transverse vesical fold (plica vesicalis transversa), when the 

 bladder is empty. 



(b) Muscular coat (tunica muscularis). 



(ba) External layer (stratum externum). 



(baa) Pubovesical muscle (M. pubovesicalis). 



(bab) Rectovesical muscle (M. rectovesicalis) . 



(bb) Middle layer (stratum medium). 



(bba) Sphincter muscle of bladder (M. sphincter ure- 

 thrae). 



What is the relation of this latter to the pros- 

 tatic muscle (M. prostaticus) 1 

 (be) Internal layer (stratum internum). 



(c) Submucous tela (tela submucosa). 



The mucous membrane of the bladder may be seen to the best 

 advantage if the bladder is opened along the anterior surface from 

 the apex to the neck. The incision should be made in the median 

 line and the urethra opened up along its whole length, to the 

 external urethral orifice. (See Fig. 289.) 



(d) Mucous membrane (tunica mucosa). 



Note that when the bladder is empty or only partially 

 distended the mucous membrane is thrown into folds. 

 Study the following: 



(da) Vesical lymph-nodules (noduli lymphatici vesicales). 



(db) Lieutaud's trigone of the bladder (trigonum vesicae [Lieu- 



taudi\ ) . 



(dba) Vesical uvula (uvula vesicae). 



(dbb) Ureteral fold (plica ureterica). 



(dbc) Orifice of ureter (oriftcium ureteris). 



Pass a probe through the ureter into the bladder 

 and note the angle at which it pierces the bladder 

 wall. Why does urine not pass from the bladder 

 back through the ureter? 



(dc) Internal orifice of urethra (orificium urethrae internum). 



(dd) Urethral ring (annulus urethralis). 



Raise carefully the mucous membrane covering the trigone 

 and note the muscular tissue in the folds which bound it. 



The penis should now be pinned down upon a block or a dis- 

 secting-tray and the mucous membrane of the different divisions 

 of the urethra examined. 



