1016 THE VRIXARY ORGANS 



of tlie papillae above, and with that of the bladder below. ^Mucous follicles of sim- 

 ple form have been found in the upper part of the canal. The muscularis is about 

 one-fiftieth of an inch (.5 mm.) in thickness, and consists of two layers, an exter- 

 nal composed of annular fibres, an internal of filn-es longitudinally disposed. After 

 the tube has entered the bladder the circular fil)res ap})ear as a kind of s})hincter 

 around its vesical orifice; wliile the longitudinal fibres spread out to foi-m with 

 those of the opjiosite side a triangular expanse witli its a})ex at the internal urinary 

 meatus and its base corresponding to a line drawn between the two ureteric orifices, 

 the upper (interureteric) and lower (uretero-meatal) fil)res forming strong bands 

 which bound the triangle 



Vessels and nerves. — The arteries of the ureter come from the renal, sper- 

 matic or utero-ovarian, internal iliac, and vesical; the veins terminatcin the corre- 

 sponding trunks; and the lymphatics pass to the renal, lumbar, and pelvic glands 

 and into the receptaculum chyli. The nerves are supplied by the spermatic, 

 renal, and hypogastric plexuses. 



Varieties. — The most important variation consists in the partial or complete 

 duplication of the tube owing to the late union or to the non-union of the superior 

 and inferior infundibula or pelves. In rare cases three pelves may in like manner 

 remain separate in part or in the whole of their course to the bladder. 



THE BLADDER 



The urinary bladder is a recej^tacle, of which tlie form, size, and position vary 

 with the amount of its contents. The adult organ in its empty or moderately filled 

 condition lies entirely below the level of the oblique plane of the pelvic inlet; but 

 when considerably distended it rises into the abdomen and shows itself beneath the 

 parietes as a characteristic mesial projection above the symphysis, a projection Avhich 

 in certain cases may extend nearly to the level of the umbilicus. It is invested over 

 its whole extent by recto-vesical fascia, and is partially covered above and behind 

 l)y peritoneum (fig. 617). 



Form, — AMien fully distended it assume^ in the male an ovoid shape Avith its 

 longest diameter directed downwards and backAvards, but in women the transverse 

 diameter is commonly the greatest, owing to the different shape of. the pelvic cavity. 

 In the child it is somewhat pear-shaped, the stalk being represented by the urachus. 



The form of the empty bladder is still doubtful, as the appearances in the dead 

 sul)ject do not necessarily coincide with the condition existing during life. In , 

 mesial sagittal section it usually appears somewhat cup-shaped, its upper Avail pre- 

 senting a rounded or pyramidal hoUoAV to the intestines, while its cavitv' is repre- 

 sented by a T or Y-shaped fissure (as in plate 1 of Symington's 'Anatomy of the 

 Child'). It is prol)able that this 'diastolic' form, as it has been termed, is not 

 altogether the normal result of a relaxation preliminary to refilling; but is ]:)artly 

 due to the loss of vital elasticity of the muscular Avail, and that the healthy living 

 bladder maintains a rounded or ovoid form even when empty. 



The three terms, ' apex ' or ' superior fundus,' ' inferior fundus,' and ' neck,' are 

 connnonly applied to parts of the bladder: the first to the point of attachment of the 

 superior ligament or urachus (a relic of the tube of communication l)ctAveen the 

 bladder and allantois) Avhich connects it Avith the umlnlicus; the second to the loAver 

 part of the organ, and the third to the point at Avhich the vesical cavity becomes 

 continuous Avith the urethra; but the expressions are all more or less o]ijectiona])le, 

 and serA'e no useful ])uri)ose. Under ordinary distension the so-called ' a})ex ' is 

 as much rounded as the rest of the viscus; the anatomical limits of the ' inferior 

 fundus' are still undefined; and the only 'neck' that can be assigned to the blad- 

 der is represented by the prostate and prostatic urethra. 



Relations. — The Idadder Avhen moderately filled may be said to present for 



