Fig. 569.—Human adult. Ileo-colic junction and cæcum. (Columbia University Museum, No. 1610.)
A similar series is shown in Figs. 569, 570 and 571. In Fig. 569, taken from an adult subject, the intermediate non-vascular fold is entirely free, the dorsal branch of the ileo-cæcal artery passes to cæcum and appendix in an area of adhesion between parietal peritoneum and the intestine which includes the dorsal vascular fold. There is consequently no caudal boundary to the ileo-cæcal fossa. Figs. 570 and 571 are both taken from infantile preparations.
In Fig. 570 the dorsal vascular and the intermediate folds nearly meet at the root of the appendix. They serve to outline the fossa, which appears completed in Fig. 571 by the actual meeting and fusion of the folds.
The Ileo-cæcal Folds in the Anthropoid Apes.—(1) Chimpanzee, Troglodytes niger.
The structures in a juvenile specimen of this animal are shown in [Figs. 460] and [461].
The ventral vascular fold ([Fig. 460], 3), containing epiploic fat, descends over the ileo-colic junction nearly to the level of the lower ileal margin. The intermediate non-vascular fold ([Figs. 460] and [461], 2), derived from the ileum opposite to the mesenteric border, passes to the ventral and left aspects of the cæcum and meets, near the root of the appendix, the dorsal vascular fold ([Fig. 461], 3) carrying the dorsal cæcal branch of the ileo-colic artery, which ramifies over the cæcum and supplies the appendix.
The appendix measures 12.3 cm. and presents a terminal hook, slightly dilated.
The appendicular mesentery terminates within the concavity of this hook and measures 1.5 cm. in width at the broadest part, about 4.5 cm. from the root of the appendix.