428 DIGESTIVE SYSTEM OF THE HORSE 
have a diameter of about twenty inches (50 cm.). This is sueceeded by a funnel- 
shaped terminal contraction. 
The right ventral part of the great colon is attached to the lesser curvature of 
the cecum by two layers of peritoneum which form the ca@co-colic fold (Plic: 
excocolica). The right parts are united by peritoneum on either side and also by 
areolar tissue and muscular fibers, the surface of contact being about four or five 
inches (ca. 10 to 12 em.) wide; the left parts are attached to each other in a similar 
fashion near the anterior flexures, but further back the connection is a peritoneal 
fold which gradually becomes wide enough to allow them to be drawn apart about 
six inches (ca. 15 cm.) near the pelvie 
flexure. The terminal part of the colon 
is attached by peritoneum and areolar 
tissue to the ventral surface of the pan- 
creas dorsally and to the base of the 
cecum laterally. It is connected in- 
directly with the diaphragm and liver 
by means of a fold derived from the 
right lateral ligament of the liver. 
The relations are complex, but the 
more important facts are as follows: 
The ventral parts have extensive con- 
tact with the abdominal wall ventrally 
and laterally. On the right side the 
colon is almost entirely excluded from 
contact with the flank by the cecum; 
on the left side it has no contact with 
the upper part of the flank, being ex- 
cluded here by coils of the small colon 
and small intestine. Dorsally the chief 
relations are tothe stomach, duodenum, 
liver, pancreas, small colon, small intes- 
tine, aorta, posterior vena cava, and 
portal vein. Since there are no trans- 
verse attachments of the right and left 
parts, and the latter have no attach- 
ment to the wall, they are subject to 
considerable displacement.' The pel- 
vic flexure is variable in position, but 
usually it is directed against the poster- 
Fig. 368.—Posrerior Portion or Lerr Parrs or Coron jor part of the right flank or lies in the 
On Honea) DoRseu NIN: right inguinal region.” 
1, Left dorsal part; 2, left ventral part; 3, pelvic flexure. fa 5 ' 
a ao : , The longitudinal bands (Teniv — 
coli) vary in number on the different 
parts. The ventral parts have four bands. The pelvic flexure has a band along 
its lesser curvature. The left dorsal colon has at first only one band, which is 
a continuation of the preceding one; further forward two other bands appear, and | 
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1 Abnormal displacement, e. g., torsion of the left parts, is not rare, and is liable to produce | 
death if not promptly reduced. 
> The length of the left parts varies and this appears partly to account for the differences to | 
be found in the arrangement of their posterior parts and the pelvic flexure. In subjects in which | 
these parts of the colon are relatively long, their posterior ends are usually bent to the right across 
the pelvic inlet so that the pelvic flexure hes to the right of the inlet. In few cases the left parts | 
of the colon seem relatively short and the pelvic flexure lies at the pelvic inlet. Other dispositions — 
are encountered. 
