allel — ‘ : 
THE BLADDER. 1093 
The part of the bladder which connects the apex with the base, and which is not 
sharply marked off from either, is called the body, or corpus vesice. 
Position of the Urethral Orifice. —During the various changes in form and 
position which the bladder undergoes, the region of the urethral orifice remains 
almost fixed in position. When the bladder is very much distended this region 
merely lies at a shehtly lower level in the pelvis than it does when the organ is 
empty ; on the other hand, distension of the lower part of the rectum raises, to 
some extent, the level of the urethral orifice. The urethral orifice les immedi- 
ately above the prostate, behind and shehtly below the level of the upper margin 
of the symphysis pubis, and about two to two and a half inches from it. It can 
be peily reached by a finger introduced into the bladder through the abdominal 
wall above the symphysis pubis. It is usually placed half an inch to one inch 
ete the level of a plane passing through the lower margin of the symphysis and 
the lower end of the sacrum, but in some cases it is found to be somewhat lower. 
In the female it normally occupies a lower level than in the male. Since the 
position of the internal urethral orifice varies, in the manner above described, with 
the condition of the rectum and of the bladder itself, it follows that it hes at its 
lowest limit when the bladder is full and the rectum empty, and at its highest 
level when the bladder is empty and the rectum distended. 
Under Aspect of the Bladder.—The lower part of the bladder, which is 
directed towards the pelvic floor, changes, as we have seen, but sheghtly with the 
varying amount of distension of the 
viscus. When the organ has been 
carefully hardened before its removal 
from the body, it is possible to map out 
on its under aspect three convex 
triangular areas which may be distin- 
cuished from one another by the direc- 
tions in which they look. The three 
areas approach one another in the 
region of the urethral orifice, where, 
in the male, a portion of the under 
aspect of the bladder wall is structur- 
ally continuous with the upper part 
of the prostate. Behind the urethral 
Bladder apex 
————Tl[Lateral border 
Infero-lateral 
~ area 
Area continuous 
with prostate 
Base of bladder 
-Ureter 
qj 
Fic. 739.— UNDER ASPECT OF THE EMPTY MALE BLADDER 
from a subject in which the viscera had been har- 
orifice 1s a triangular district, directed dened in siti. 
downwards and backwards, and related, The prostate has been severed from the bladder, and the 
in the male, to the seminal vesicles white area in the drawing indicates the position 
. : : ; where the two structures were continuous. 
and the terminal portions of the vasa K eae: 
deferentia which, together with the recto-vesical layer of the pelvic fascia, 
intervene between this part of the bladder and the rectum. This triangular 
area of the bladder wall is known as the base, or postero-inferior surface of the 
bladder, and in the femaie is directed against the anterior wall of the vagina. 
The rest of the under aspect of the bladder is formed by two infero-lateral areas, 
or surfaces, which meet in the middle line in front of the urethral orifice, and are 
directed for the most part downwards and outwards (see Fig. 739). Each of these 
areas extends backwards to join the postero-inferior surface, or base, along a 
rounded border which lies between the point where the ureter reaches the bladder 
and the urethral orifice. The infero-lateral part of the bladder wall rests against 
the fascia covering the levator ani and obturator internus muscles, and, nearer the 
middle line, upon the as and retro-pubie pad of fat. 
The three rounded borders which mark off the three triangular areas on the 
under aspect of the bladder, just described, extend from the region of the urethral 
orifice to the bladder apex, ‘and to the points where the ureters reach the bladder 
wall (see Fig. 739). 
Shape and Relations of the Empty Bladder.— When the bladder is empty, 
or nearly so, it has, roughly speaking, the shape of an inverted tetrahedron, whose 
apex corresponds to the point where the urethra leaves the organ, while the base 
of the tetrahedron is formed by the superior surface of the bladder. The three 
Ri 
