Large Intestines of the Ruminants
2. Colon:
A. Ascending colon:
The proximal loop of ascending colon continues cranially from the cecum at the ileocecal orifice. At first its diameter is same as that of the cecum, but decreases in size. Ventral to the right kidney the proximal loop doubles back on itself dorsolaterally between the cecum and the descending duodenum. Then it doubles on itself once more mediodorsally, and passes cranially on the left side of the mesentery to become continuous with the spiral loop. In the ox the spiral loop is formed of two centripetal turns, the central flexure and two centrifugal turns. In sheep and goats there are usually three centripetal and three centrifugal turns. The distal loop proceeds from the last centrifugal turn (gyrus) dorsally and caudally on the proximal loop. It turns around the caudal border of the mesentery from left to right and then passes cranially medial to the proximal loop. The distal loop joins the short transverse colon.
B. Transverse colon:
It passes from right to left around the cranial surface of the cranial mesenteric artery and is continued by the descending colon.
C. Descending colon:
The descending colon passes caudally dorsal to the descending duodenum. It forms slight sigmoid flexure near the pelvic inlet and joins the rectum.
3. Rectum:
It continues the descending colon into the pelvic cavity. Its short caudal part is retroperitoneal.