i ; THE ABDOMINAL CAVITY. 1227 
The orifice of the appendix opens upon the postero-internal aspect of the 
excum about an inch below the ileo-czeeal valve. The appendix will generally be 
found to pass either upwards and inwards behind the lower end of the ileum, or 
downwards and inwards so as to overhang the external iliac vessels at the brim of 
the pelvis; less frequently it ascends in the pouch behind the commencement of 
the ascending colon. The blood supply of the appendix is derived from a single 
artery (a branch of the ileo-colic) which occupies the small mesentery of the 
appendix ; hence interference with the flow of blood along this vessel, either 
mechanically or from disease, predisposes to gangrene of the appendix. In expos- 
ing the appendix, the centre of the incision should be about 1 in. below and 
external to the mid-point between the umbilicus and the anterior superior iliac 
spine. The sheath of the rectus should, if possible, not be opened. After dividing 
the peritoneum, the appendix is sought for by passing the finger behind the angle 
formed by the inner aspect of the czecum and the lower end of the ileum. It may 
be necessary to bring the cxecum out of the wound, in order that: the anterior 
longitudinal band of muscular fibres (tenia coli) may be traced downwards to the 
root of the appendix. 
The ascending colon, after crossing the iliac crest, lies deeply in the night 
lumbar region upon the quadratus luamborum and the right kidney. 
The hepatic flexure reaches upwards beneath the tenth costal cartilage into the 
lowest’ part of the right hypochondrium, where it lies immediately to the right of the 
gall-bladder, between the liver and the lower half of the anterior surface of the kidney. 
The transverse colon crosses the upper part of the umbilical region. Not 
infrequently it forms a U-shaped or a V-shaped loop which reaches for a variable 
distance below the level of the umbilicus; when the intestines are distended it 
-Inay ascend in front of the stomach. 
The splenic flexure reaches upwards behind the greater curvature of the 
stomach into the left hypochondriac region, as far as the lower extremity of the 
spleen, from which it is separated by the costocolic fold of peritoneum. 
The descending colon lies deeply in the left lumbar region, along the lower half 
. 
| of the outer border of the left kidney. 
The iliac and pelvic portions of the colon lie respectively in the left iliac fossa 
-and in the true pelvis; the latter is provided with a distinct mesentery which, 
a it crosses the left ureter and the bifurcation of the common iliac vessels, forms 
the intersigmoid peritoneal fossa. This fossa is sometimes the starting-point of an 
| internal retroperitoneal hernia. The mouth of the fossa looks downwards and to the 
left ; above and to its right is the sigmoid artery. The iliac colon can generally be felt 
through the abdominal wall as it descends from the crest of the ileum to the inner 
‘margin of the psoas muscle. The iliac colon is the part of the bowel which is most 
frequently opened when it is desired to make an artificial anus. It is exposed 
through an oblique incision, the centre of which is at the junction of the middle and 
outer thirds of a line drawn from the umbilicus to the anterior superior iliac spine. 
Kidneys.—The kidneys, which lie behind the peritoneum, extend higher up 
than is often supposed, and laterally they do not extend so far away from the 
spine as is almost invariably depicted ; hence it is that, unless enlarged, the kidneys 
can seldom be felt through the abdominal wall. The right kidney as a rule hes a 
little lower than the left, as well as a little further away from the mesial plane. 
The hilus of the right kidney lies 2 in. from the mesial plane; that of the left 
14 in. from the mesial plane. For practical purposes the hilus of the kidney may be 
regarded as opposite a point on the anterior abdominal wall a finger’s breadth 
internal to the tip of the ninth costal cartilage; and a line joining the two hih 
erosses the vertebral column opposite the disc between the first and second lumbar 
vertebrie, that is to say, on a level with the transpyloric me. The highest point 
of the kidney is situated two inches from the mesial plane, on a level with a line 
crossing the abdomen midway between the xiphisternal and transpyloric planes. The 
lowest point of the kidney reaches down to, or a little below, the infracostal plane. 
The student should make himself familiar with the feel of the parts im relation 
to the kidneys, as far as they can be made out by introducing the hand through a 
esial abdominal incision. The lower half of the right kidney is covered by the 
