| , THE COLON. 1035 
and somewhat inwards, lying in front of the iliacus muscle. A little way above 
Poupart’s ligament it turns inwards over the psoas, and ends at the inner border 
of this. muscle by dipping into the pelvis and becoming the pelvic colon (Fig. 699). 
It usually measures about 5 or 6 inches (12°5 to 15 cm.) in length, but it varies 
considerably in this respect. 
Relations.— Behind, it lies upon, and, as a rule, is connected by areolar tissue to, 
the front of the ilio-psoas muscle. Jn frond, it 1s ‘usually covered by coils of small 
intestine, which hide it from view; but when distended, or when it occupies a lower 
position than usual, it comes into direet contact with the anterior abdominal wall. 
As a rule (90 per cent 
of bodi Jonnesco), 
it is covered by peri- 
toneum only on its an- 
terior and two lateral [uieree or 
surfaces. Occasionally _ Situation of 
> “ intersigmoid- 
(10 per cent of cases) it “fossa 
18 completely covered, ee colton 
has a short mesentery 
Ea 9 Oe Pelvic 
@! inch, ZiEO ems) AI +. snesscoton 
is Shehtly movable. Beginning of 
= ‘i rectum 
In its course it passes 
down over the iliac fossa 
near its middle, generally — Pelvic colon 
forming a curve with its 
concavity directed in- 
wards and upwards, and 
ee reached a point 
14 or 2 inches (4 to 5 em.) 
above ‘Poupart’ s ligament, 
it turns inwards across the 
psoas towards the pelvic 
cavity. Occasionally the 
iliac colon occupies a lower 
position than usual, and 
runs along the deep sur- Fic. 700.—THE ILIAC AND PELVIC COLONs, from a formalin-hardened male 
Bladder 
face of Poupart’ s ligament, body, aged 30. 
immediately behind the The pelvic colon was unusually long ; its course is shown, as well as that of the 
anterior abdominal wall. beginning of the rectum, by dotted lines. It first ran across the upper 
surface of bladder to the right pelvic wall, then recrossed the pelvis in a 
Pelvic Colon line posterior to its first crossing ; finally it returned towards the middle 
(colon pelvinum).— line, and passed into the rectum. As a rule, after crossing to the right 
side of the pelvis, the pelvic colon turns backwards and inwards to reach 
F TA 2 "pag - Q Re 
This corresponds to the middle line, where it passes into the rectum. 
the portion of the 
“sigmoid flexure” which lies in the pelvis, together with the so-called “ first part of 
the rectum.” The pelvic colon is a large coil of intestine, which begins at the inner 
border of the left psoas muscle, where it is continuous with the ilaec colon, and 
ends at the level of the third sacral vertebra by passing into the rectum proper. 
Between these two points it has a well-developed mesentery, and forms a large and 
variously-shaped coil, which usually les in the cavity of the pelvis (95 per cent). 
Whilst the loop of the pelvic colon is very irregular in form, the following may 
be given as perhaps its most common arrangement. Beginning at the inner margin 
of the left psoas, it first plunges over the brim into the pelvis, and crosses this 
cavity from left to right; it next bends backwards and then returns along the 
posterior wall of the pelvis towards the middle line, where it turns down and passes 
into the rectum (Figs. 699 and 700). 
Relations.—In its passage into the pelvis it crosses the external iliac vessels : 
in running from left to right across the cavity, 1t rests on the bladder or uterus, 
according to the sex ; whilst above it lie the coils of the small intestine. 
It is completely covered by peritoneum, and is furnished with an extensive 
mesentery—the pelvic mesocolon—which permits of considerable movement. 
Sometimes, when longer than usual (Fig. 700), the pelvic colon, in returning from the right 
side of the pelvis, crosses the middle line, ¢ going even as far as the left wall, and then turns 
