Arrangement of the tunica muscularis of the ileum, cecum and colon at the transition between the small and the large intestines of swine.

The arrangement of the bundles of muscular fibers in the transition between the small and the large intestines was studied in 12 male adult crossbred swine by dissection, after immersion in 50% nitric acid solution. The connection between the small and the large intestines was formed by the association of the muscular tissue, the connective tissue and the fat tissue. The tunica muscularis of these organs was organized in thin thread-like bundles and wide ribbon-like bundles of variable width and thickness. The superficial bundles of the longitudinal stratum of the tunica muscularis of the ileum established the continuity with the large intestine; the deep bundles penetrated into the ileal papilla. The limit between the cecum and the ascending colon was externally marked by the sulcus cecocolicus dorsalis and ventralis. The connection between the cecum and the ascending colon was formed by bundles of muscular fibers coming from the ileum, and the taeniae ventralis, lateralis and medialis of the cecum. Some bundles of muscular fibers from the ascending colon and the cecum headed toward the sulcus cecocolicus. The median bundles of muscular fibers of the taenia ventralis of the cecum, near the termination of the ileum, were arranged to form a loop around the termination of the ileum, mixing with the musculature of the ascending colon at the level of this junction.