1040 THE DIGESTIVE SYSTEM. 
on the other hand, it may be considerably higher than normal, sometimes being placed at a dis- 
tance of 4 or 44 inches (10:0 to 11:2 em.) from "the anus. It should also be added ate the level is 
generally believed to be somewhat raised by distension of the rectum and bladder, and lowered 
by emptying these viscera, although this is denied by Jonnesco. 
In the child at birth, the peritoneum extends down to the base of the prostate (Symington), 
and is thus lower in relation to the bladder; but this may be partly accounted for by the high 
position of this organ in the child. 
As a rule it will be found that 2 inches (5:0 em.) of the front of the reetum, exclusive of the anal 
canal, are entirely free from peritonewn, and it is this and the adjacent portion of the bowel which, 
being free from the restraining influence of the peritoneum, is most distensible, and is known as 
the rectal ampulla. Including the anal canal, 35 inches (8°7 em.) of the rectum, measured along 
the front of the tube, have no serous covering. On the other hand, the back is free from peri- 
toneum for 5 or 6 iaches (12°5 to 150 cm.)—or sometimes much mor Ae the anus. 
It is also of interest to notice that the connexion of the peritoneum to the rectum varies in 
its character at different parts :—Above and in front it is closely adherent, and can be removed 
only with the greatest difficulty ; at the sides and below the connexion is much looser. As a 
Second sacral vertebra ponding of pelvic mesocolon 
Sacro-iliae joint 
/ 
Rectum Liss 
y 
Pararectal fossa 
Ureter (cut) hs wS 
Crescentic fold of NMG 
peritoneum (recto- [3 Ni 
genital fold) sé 
Seminal vesicle 
beneath this < 
_v Ureter (cut) 
Internal iliac artery 
_— Obturator nerve 
External iliac 
es Fossa 
obturatoria 
ae (Waldeyer) 
External iliac 
artery 
: : Iliacus 
Deep epigastric artery 
Ureter J External iliac artery 
j : 
Ia ravesic Osse 7 
Paravesical fossa Vas deferens 
: A ee f / / \ \ 
Plica vesicalis transversa Vi 7, \ \ Obliterated hypogastric artery 
/ / \ ed z e 
Rectus Bladder 
Pyramidalis Urachus 
Fic. 703.—THE PERITONEUM OF THE PELVIC CAVITY. 
The pelvis was sawn across obliquely in a thin male subject aged 60. Owing to the absence of fat the various 
pelvic organs were visible through the peritoneum, though not quite as distinctly as represented here. 
The bladder and rectum were both empty and contracted ; the paravesical and pararectal fossa, as a 
result, were very well marked. 
result, the peritoneum can be stripped off the rectum in its lower third or half without much 
difficulty, whilst in its upper portion this is not the case—an arrangement which admits of the 
free expansion of the rectal ampulla. 
General Relations of the Rectum (Figs. 701 and 702).—Behind, the rectum 
rests on the front of the sacrum and coccyx, and below these upon the posterior part 
of the pelvic floor—here formed by the meeting of the two levatores ani in the ano- 
coecygeal raphe. When much distended it also comes into relation on each side with 
the lower part of the pyriformis and the sacral plexus. The bowel is separated 
from these structures by a very considerable amount of connective tissue, arranged 
(apparently in several layers) around the tube. In this tissue the two chief 
branches of the superior heemorrhoidal vessels he behind the upper part of the 
bowel, but lower down they are placed in relation to its sides. 
At its sides above are the pararectal fossee and their contents (pelvic colon, or 
ileum); below this the rectum is in contact with the coccygei and levatores ani 
