The Anatomy of the Human Peritoneum and Abdominal Cavity / Considered from the Standpoint of Development and Comparative Anatomy

by George S. Huntington

[Figs. 462] and [463] show the cæcum of the adult chimpanzee in the ventral and dorsal view. The ventral vascular fold ([Fig. 462], 1) is well developed, heavily fringed with epiploic appendages.

The non-vascular fold is extremely short and tense, fusing with the short appendicular mesentery near the point where in the dorsal view ([Fig. 463]) the appendix is seen bent at its origin sharply to the right.

[Fig. 464], also taken from an adult specimen of the same animal, shows a very well-developed dorsal vascular fold, which fuses with the intermediate fold to limit a distinct ileo-cæcal recess.

The chimpanzee, therefore, agrees closely with the human subject in the arrangement of the folds.

(2) Orang, Simia satyrus.

In [Figs. 458] and [459] the arrangement of the folds in an adult specimen of the orang is shown.

The ventral cæcal artery ([Fig. 458]) is well developed, forming with the peritoneal fold and epiploic appendages surrounding it, a sharp sickle-shaped edge which descends over the ventral surface of the ileo-colic junction following the curve of the left cæcal margin, and turning its concavity to the left toward the entering ileum.

The ventral cæcal artery follows the left margin of the cæcum below the ileo-cæcal junction and passes for 0.5 cm. upon the portion of the pouch which turns up behind the terminal ileum.

The dorsal cæcal artery is a vessel of large size, supplying branches to the narrow appendicular mesentery which extends, with many epiploic appendages, to within 9 mm. of the blunt apex of the appendix. 2.5 cm. beyond the first bend in the appendix the fold is narrowed to a fringe not more than 0.75 cm. wide. Up to this point the dorsal vascular fold measures 1.5 cm. in width, and just where it narrows it is joined by the intermediate non-vascular fold ([Fig. 459]), which forms a membranous band, 3.3 cm. wide in the middle, spread out in the angle between the lower and dorsal surfaces of the ileum and the dorsal surface of the cæcum which turns up behind the ileo-colic junction. Between this fold and the dorsal vascular fold is seen the deep recess of the posterior ileo-cæcal fossa—which by reason of the sharp curve of the cæcum looks not only to the left but also upward and backward.