THE ABDOMEN 85J 



portions. The lateral borders start from the apex, whence they 

 pass backwards in a diverging manner, and each marks the separa- 

 tion between the superior surface and the corresponding half of the 

 inferior surface. Posteriorly each lateral border meets the posterior 

 border. The posterior border extends transversely between the 

 superior surface and the base. At either end it is joined by the 

 lateral border. The lateral or ureteric angles are situated on either 

 side at the junction of the lateral with the posterior border. At 

 these angles the ureters pass through the vesical wall. The neck is 

 situated at the meeting of the base and inferior surface. It is 

 surrounded by the base of the prostate gland, and it is in this 

 situation where the vesical cavity becomes continuous with the 

 urethra. The neck lies fully 2 inches behind the symphysis pubis, 

 being a little lower than its upper border, and it is practically fixed 

 in position by the prostate gland and pubo-prostatic ligaments. 



The external trigone is the name given to a limited triangular 

 space upon the exterior of the base, which is bounded as follows : 

 above, by the bottom of the recto-vesical pouch of peritoneum ; 

 laterally, by the ampulla of the vas deferens, external to which is 

 the vesicula seminaJis ; and below, by the approximation of the 

 common ejaculatory ducts at the base of the prostate gland. The 

 length of the space from the apex below to the base above is, as 

 a rule, fully i inch, but its breadth is limited by the encroachment 

 upon it of the deferential ampullae. There is no peritoneum over 

 this region. 



The bladder during distension, and when fully distended. As 

 the bladder becomes distended the neck alters its position only to 

 a very slight extent in a downward direction. The demarcations 

 between the component parts of the viscus gradually disappear, and 

 it becomes ovoid. The apex appears above the symphysis pubis, 

 and, as the organ increases in size, the apex and the superior portion 

 of the body ascend into the hypogastrium in such a manner as to 

 strip of? the parietal peritoneum from the back of the linea alba. 

 In this way a portion of the original inferior surface, devoid of 

 peritoneum, is brought into direct contact with the back of the linea 

 alba, which is now also free from peritoneal covering. A distended 

 bladder may, therefore, be punctured or opened through the linea 

 alba above the symphysis pubis without doing any injury to the 

 peritoneum. The bladder is now becoming spheroidal, and its long 

 axis is directed downwards and backwards. The part which 

 rises highest is not the original urachal apex, but that part of the 

 superior surface which is immediately adjacent to, and behind, the 

 apex. 



Peritoneal Relations. — ^The only part of the bladder which is 

 covered by peritoneum is the superior surface. The peritoneum is 

 reflected from the apex along the urachus, and at either side it 

 leaves the organ along the lateral border. When the bladder is 

 distended the lateral reflection of peritoneum appears to take place 

 along the covu-se of the obliterated hypogastric artery, but this 



