ANATOMY IN A NUTSHELL. 471 



communicate with the venous plexus in the adipose capsule and by means of 

 this with the visceral and parietal veins close by. These vein> are very dis- 

 tinct when the organ is congested. 



The renal lymphatics may be divided into two sets, capsular and parenchy- 

 matous. They terminate in a series of glands lying with the renal vessels in 

 the subperitoneal tissue, and their contents are ultimately conveyed into the 

 receptaculum chyli. 



LESSON CLI. 



The ureter (Plate VIII.) is a tube conveying the urine from the kid- 

 ney to the blader in mammals, or into the cloaca in case no bladder exists. 

 The human ureter is a slender tube from fifteen to eighteen inches long running 

 from the pelvis of the kidney to the base of the bladder, at the posterior angle 

 of the trigonum. It is behind the peritoneum and rests upon the Psoas muscle. 



Its structure includes (1) a fibrous coat. (2) longitudinal and circular 

 muscular fibers, and (3) a lining of mucous membrane with vessels and nerves 

 from various sources. The ureter pierces the wall of the bladder very oblique- 

 ly. It runs for nearly an inch behind the muscular and mucous coats of the 

 bladder. 



Blood Supply. — (1) The renal, (2) Spermatic. (3) Internal iliac, and 

 \ Inferior vesical. 



Nerve Supply. — (1) Inferior mesenteric. (2) Spermatic plexus, (3) Pel- 

 vic plexus. 



The bladder is the reservoir in which the urine is collected from the ureters. 

 It has four coats. (1) the mucous, which is nearest the cavity. (2) the areolar. 

 (3) the muscular, and (-4) the serous. The trigonum is a triangular space or 

 area at the base of the bladder, whose apex is at the beginning of the urethra. 

 and whose other two angles are at the point of entrance of the ureters into the 

 bladder. 



When the bladder is collapsed its mucous walls fall together in such a way 

 that a sagittal section shows the line between them in the shape of a V with 

 unequal and widely spread arms, the point of the V indicating the opening of 

 the urethra. Its dimensions are three by five inches. It> capacity is about 

 a pint. In the child the bladder is almost an abdominal organ, while in the 

 adult it is in the pelvis. 



The urachus is a fibrous cord extending from the fundus of the bladder to 

 the umbilicus. It represents in the adult a part of the sac of the allantoic and 

 associate allantoic vessels of the fetus, whose cavities have been obliterated. 

 It is that intra-abdominal section of the navel-string which is constituted by 

 bo much of the allantoic sac and hypogastric arteries a- becomes impervious, 

 the section remaining pervious being the bladder and superior vesical arteries. 

 It sometimes remains pervious, as a malformation, when the child may urinate 

 l)v the navel. 



