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

by George S. Huntington

1. Either the retro-colic appendix has become early attached to the adjacent large intestine, whose dorsal surface in large part remains free, or

2. The arrangement of the peritoneum indicated in schema, [Fig. 552], may be subsequently changed into that shown in schema, [Fig. 553], by a continued downward displacement of the cæcum, producing a secondary serous investment of the dorsal surface of appendix and part of ascending colon.

Examples of this type are found both in infantile and adult subjects.

In [Fig. 538], taken from an infant three years of age, the cæcum is lifted up to show the vertical position of the appendix behind the cæcum and ascending colon, the dorsal surface of the large intestine retaining its free serous covering. Another illustration of this arrangement in a juvenile subject is shown in [Fig. 529]. The same condition in the adult subject is illustrated in [Figs. 539] and [540].

Fig. 559.—Human infant. Ileo-colic junction and cæcum; dorsal view. Retro-colic appendix, adherent to the free dorsal serous surface of the large intestine, with intermediate extraperitoneal segment. (Columbia University Museum, No. 1638.)

(c) (Schema, [Fig. 554].)—Occasionally, with the appendix erected vertically behind the ascending colon, the apex of the cæcum and the proximal portion of the appendix are invested by peritoneum for a short distance and the tip of the appendix likewise obtains a free serous investment, while the intermediate greater portion of the appendix and the corresponding segment of the dorsal surface of the ascending colon are extraperitoneal, adherent to the abdominal parietes. Examples of this peritoneal relation of the appendix in an infant are shown in Figs. 559 and 560, while [Fig. 509] represents the same arrangement in an adult specimen. The condition is produced from the arrangement of schema, [Fig. 554], by secondary adhesion and obliteration of the serous surfaces over the intermediate portion of the retroverted appendix and the adjacent dorsal surface of the ascending colon.

Fig. 560.—Human adult. Ileo-colic junction and cæcum; dorsal view. Appendix with intermediate non-peritoneal segment, while the proximal portion and the tip are covered by serous investment. (Columbia University Museum, No. 1615.)

C. ILEO-CÆCAL FOLDS AND FOSSÆ.