It will be observed that beyond the duodeno-colic isthmus the coils of the jejuno-ileum have resulted from the increase in length of the descending limb, the apex and the proximal part of the ascending or recurrent limb, carrying the ileo-colic junction and cæcum. The remainder of the ascending limb, terminating in the embryonic condition at the splenic flexure by passing into the descending colon, has in the course of further development in this individual produced a straight segment—the misplaced ascending colon—and a convoluted and bent representative of the normal transverse colon.

The same disposition of the large intestine may be noted in the other preparations.

Fig. 120.—Abdominal viscera of adult human male; non-rotation of intestine. (Columbia University Museum, Study Collection.)   Fig. 121.—Abdominal viscera of adult human male; non-rotation of intestine. (Columbia University Museum, Study Collection.)
Fig. 122.—Abdominal viscera of child, two years old; non-rotation of intestine. (Columbia University Museum, Study Collection.)   Fig. 123.—Human fœtus at term; abdominal viscera, hardened in situ; non-rotation of cæcum. (Columbia University Museum, No. 1813.)

Fig. 122 shows an instance of non-rotation observed in the human infant at two years of age.

Fig. 123, taken from a fœtus at term, shows the result of failure to completely rotate in the region of the cæcum and ileo-colic junction. The rest of the large intestine has rotated as usual and assumed the normal position. The terminal ileum, however, passes behind the cæcum and enters the large intestine on its right side; the cæcum is turned upwards and to the right and the appendix lies ventrad of the beginning of the ascending colon. In order to produce the normal arrangement, shown in Fig. 124, taken from another fœtus at term, it would be necessary to turn the cæcum and ileo-colic junction in Fig. 123 through half a circle. The cæcum would then turn upwards and to the left, the ileum entering the large intestine from left to right, and the appendix would be placed behind the cæcum and ileo-colic junction. Figs. 125 and 126 show the normal and abnormal arrangement presented by these two preparations diagrammatically. The instances in which in the adult the ileo-colic entrance is placed on the right side of the large intestine and in which the appendix is situated laterad of the ascending colon unquestionably find their explanation in the failure of the intestine to completely rotate at the ileo-colic junction.

Fig. 124.—Human fœtus at term; abdominal viscera, hardened in situ; normalposition of completely rotated cæcum and appendix. (Columbia University Museum,No. 1814.)

 

Figs. 125, 126.—Schematic representation of final stages in rotation of cæcum and large intestine.

Fig. 125.—Just before final rotation of cæcumand terminal ileum. Concavity of cæcum directedcephalad and to right. Terminal ileum enterscolon from right to left.

 

Fig. 126.—Rotation completed. Concavityof cæcum turns caudad and toleft. Terminal ileum enters colon fromleft to right.

Fig. 127.—Adult human subject with non-rotated cæcum. The terminal ileum turns caudad from right to left to enter right side of colon.