84. Large intestine.—Let us now trace the large intestine and see where it is accessible to pressure. The ‘cæcum,’ or ‘caput coli,’ and the ileo-cæcal valve lie in the right iliac fossa. The ascending colon runs up the right lumbar region over the right kidney. The transverse colon crosses the abdomen two or three inches above the umbilicus. The descending colon lies in the left lumbar region in front of the left kidney. The sigmoid flexure occupies the left iliac fossa.
Throughout this tortuous course, except at the hepatic and splenic flexures, the colon is accessible to pressure, and we could, under favourable circumstances, detect hardened fæces in it. In a case which occurred in St. Bartholomew’s Hospital, a collection of fæces in the transverse colon formed a distinct tumour in the abdomen. All the symptoms yielded to large and repeated injections of olive oil. In another case an accumulation of fæcal matter in the sigmoid flexure during life was mistaken for a malignant disease.
85. Colotomy.—The operation of opening the colon (colotomy) may be done in the right or left loin, below the kidney, in that part of the colon not covered by peritoneum.
The landmarks of the operation are:—(1) The last rib, of which feel the sloping edge; (2) the crest of the ilium; (3) the outer border of the ‘erector spinæ.’ The incision should be about three inches long, midway between the rib and the ilium. It should begin at the outer border of the ‘erector spinæ,’ and should slope downwards and outwards in the direction of the rib. The edge of the ‘quadratus lumborum,’ which is the guide to the colon, is about one inch external to the edge of the ‘erector spinæ,’ or three full inches from the lumbar spines. The line of the gut is vertical, and runs for a good two inches between the lower border of the kidney and the iliac crest on the left side; rather less on the right.
Small intestines.—All the room below the umbilicus is occupied by the small intestines. The coils of the jejunum lie nearer to the umbilicus (one reason of the great fatality of umbilical herniæ). Those of the ilium are lower down.
On the right side, a little below the ninth rib, the colon lies close to the gall bladder, and is, after death, sometimes tinged with bile. Posteriorly, this part of the colon is in contact with the kidney and duodenum.
86. Bladder.—When the bladder distends, it gradually rises out of the pelvis into the abdomen, pushes the small intestines out of the way, and forms a swelling above the pubes, reaching in some instances up to the navel. The outline of this swelling is perceptible to the hand as well as to percussion. More than this, fluctuation can be felt through the distended bladder by tapping on it in front with the fingers of one hand, while the forefinger of the other passed up the rectum feels the bottom of the ‘trigone.’
THE PERINEUM.
The body is supposed to be placed in the usual position for lithotomy.
87. Bony framework.—We can readily feel the osseous and ligamentous boundaries of the perineum; namely, the rami of the pubes and ischia, the tuberosities of the ischia, the great sacro-ischiatic ligaments, and the apex of the coccyx. This framework forms a lozenge-shaped space. If we draw an imaginary line across it from the front of one tuber ischii to the other, we divide this space into an anterior and a posterior triangle. The anterior is nearly equilateral, and, in a well-formed pelvis, its sides are from three to three and a half inches long. It is called the urethral triangle. The posterior, containing the greater part of the anus and the ischio-rectal fossa on each side, is called the anal triangle.