Large Intestines of the Horse

1. Cecum:

The cecum of the horse is comma-shaped and situated chiefly to the right of the median plane. It extends from the right iliac and sublumbar regions to the floor of the abdomen caudal to the xiphoid cartilage. For description it presents a base, a body, and an apex. The base of the cecum is the most dorsal part. It is strongly curved, with its greater curvature dorsally and its lesser curvature ventrally. Connected with the lesser curvature are the termination of the ileum and the origin of the colon.

The body extends cranioventrally from the base and rests largely on the abdominal floor. It gradually tapers toward the apex. The body of the cecum has four longitudinal bands, the dorsal, ventral, medial and lateral. The four muscular bands make four rows of sacculations. The ileocecal fold attaches the ileum to the dorsal band of the cecum, whereas the cecocolic fold attaches the right ventral colon to the lateral band of the cecum. The apex lies on the abdominal floor, usually to the right of the median plane behind the xiphoid cartilage.

The ileum terminates into the cecum through the ileocecal orifice (opening) on the lesser curvature of the base of the cecum. It is partially telescoped into the cecum and it is surrounded by a fold of mucous membrane. The cecocolic orifice connects the base of the cecum with the ascending colon. It is about two inches caudolateral to the ileocecal orifice. The two openings are separated by a large fold which projects into the interior of the cecum.