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1024 THE DIGESTIVE SYSTEM. 
The rectum, the terminal part of the large bowel, succeeds the pelvic colon, 
and ends at the anal orifice. 
In its course the large bowel is arranged in an arched manner around the 
small intestine, which lies within the concavity of its curve (Fig. 670). 
In length, t the oreat intestine is equal to about one-fifth of the whole intestinal 
canal, and usually measures between 5 and 54 feet (180 to 195 em.). Its breadth is 
greatest at the caecum, and from this—with the exception of a dilatation at the 
rectum—it gradually decreases to the anus. At the cecum it measures, when 
distended, about 3 inches (75 mim.) in diameter; beyond this it gradually 
diminishes, and measures only 1} inch (37 mm.) or less in the descending and 
illae divisions of the colon. 
The large intestine, with the exception of the rectum and vermiform appendix, 
nee be easily distinguished Horn ae ROgUEn erates Sel Beene by () 
the presence of three lon: 
(Fig. 692); (6) by the f fact ne its il are sacculated ; and () i. a tsence 
of numerous little peritoneal processes, known as appendices epiploice, projecting 
from its serous coat. In addition, the larger intestine is usually wider than the 
small, but too much reliance cannot be placed on this character, for the jejunum is 
often—indeed, generally —wider than the empty descending colon. 
Tznie Coli. In the large bowel, unlike the small, the longitudinal fibres of 
the muscular coat do not form a complete layer, continuous all round’ the tube, 
sacculations ‘Tenia coli 
Appendices epiploice 
Fic. 692.—LARGE INTESTINE. 
A piece of transverse colon from a child two years old. ‘The three chief characteristics of the large intestine— 
sacculations, tenia, and appendices epiploicee—are shown. 
but, on the contrary, are broken up (Fig. 692) into three bands, known as the 
tenie coli, These bands, which are about } inch (6 min.) wide, begin at the base 
of the vermiform appendix, and run along the surface of the gut at nearly equal 
distances from one another until the rectum is reached. Here they spread out 
and form a layer of longitudinal muscular fibres, which is continuous all round the 
tube (see page 1056). The bands are about one-sixth shorter than the intestine to 
which they belong; consequently, in order to accommodate the bowel to the length 
of the teni, the gut is tucked up, giving rise to a sacculated condition (Fig. 692). 
Three rows of pouches or saccules are thus produced, alone the length of the tube, 
between the tenis. If the tenice be dissected off, the sacculations cisappear, 
the intestine becomes cylindrical, and at the same time about one-sixth longer. 
The appendices epiploice (Fig. 692) are little processes or pouches of peritoneum, 
venerally more or less distended with fat, except in emaciated subjects, which 
project from the serous coat along the whole length of the large intestine, with the 
exception of the rectum proper. 
When the interior of a piece of distended and dried large intestine is examined, its 
saccules appear as rounded pouches (haustra), separated by crescentic folds (plice 
semilunares coli), correspondiug to the creases on the exterior separating the saccules 
from one another. 
The position of the three teenie on the intestines is as follows :—On the ascending, descending, 
and iliac colons one tenia lies on the anterior aspect of the gut, and two behind, namely, one to 
the outer (postero-external), the other to the inner side (postero- -internal). It is chielly along 
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