The ventral wall and part of the lateral walls of the abdomen are
removed. _C_, Cæcum; _r.v.C._, right ventral part of colon; _v.Q._,
sternal flexure of colon; _l.v.C._, left ventral part of colon;
_d.Q._, diaphragmatic flexure of colon; _D_, small intestine; _M_,
small colon; _a_, ventral free band of cæcum; _b_, inner band of
cæcum; _c_, lateral band of ventral part of colon; _d_, ventral band
of ventral part of colon; _e_, point of elbow; _f_, anterior end of
sternal region; _g_, xiphoid cartilage; _h_, teats. (After
Ellenberger-Baum, Top. Anat. d. Pferdes.)
]
The =caliber= of the great colon varies greatly at different points. At
its origin it is only about two to three inches (ca. 5 to 7.5 cm.) in
diameter. This soon increases to about eight to ten inches (ca. 20 to 25
cm.) for the ventral portions. Beyond the pelvic flexure the diameter is
reduced to about three or four inches (ca. 8 to 9 cm.). Near the
diaphragmatic flexure the caliber rapidly increases, and reaches its
maximum in the last division, where it may be about twenty inches (50
cm.) in its widest part. This is succeeded by a somewhat funnel-shaped
terminal contraction.
[Illustration: