) | THE CAECUM AND APPENDIX. 1025 
at | eacail 
the first of these (the anterior) that the appendices epiploicee are found. On the transverse 
colon their arrangement is different, but 1s rendered exactly similar by tuming the great 
omentum, with the colon, up over the thorax. On the transverse colon in the natural position, 
the anterior tenia of the ascending and descending colons becomes the posterior (or postero- 
inferior, tenia libera), the postero- -external becomes the anterior (or omental), and the postero- 
internal the superior or mesocolic. The anterior and postero-external tenia of the iliae eolon 
pass below on to the front of the pelvic colon and rectum. 
In formalin-hardened bodies portions of the large intestine, but particularly of the fee ending 
and sigmoid colons, are often found fixed in what appears to be a state of contraction, when 
they are reduced to a diameter of about $ or # of an inch (16 to 19 mm.). Under similar con- 
ditions parts of the small intestine are found correspondingly reduced. 
The appendices epiploicie, although generally said to be absent in the foetus, can be distinctly 
seen as early as the seventh month, but at this time they contain no fat. 
Structure of the Large Intestine. — The serous coat is complete on the 
vermiform appendix, czecum, transverse colon, and pelvic colon; incomplete on the 
ascending, descending, and ae divisions of he colon and on the rectum. It will be 
described in detail with each of these portions of the intestine. 
The mucous coat is of a pale, or yellowish, ash colour in the colon, but becomes much 
redder in the rectum. Unlike that of the small intestine, its surface is smooth, owing to 
the absence of villi, but it is closely studded with the orifices of numerous large 
Lieberkithn’s glands. Solitary glands are also numerous, particularly in the vermiform 
process (Fig. 697). 
Vessels and Nerves.—The cecum and vermiform appendix receive their blood from the 
ileo-colic artery ; the ascending colon from the right colic; and the transverse colon from the 
middle colic which lies in the transverse mesocolon. These are all branches of the superior 
inesenteric artery. The descending colon is supphed by the left colic, and the iliac and pelvie 
colons by the sigmoid arteries, branches of the inferior mesenteric. The rectum derives its blood 
from the three hemorrhoidal arteries, which will be described with that division of the gut. 
The veins correspond to the arteries, and join the inferior and superior mesenteric vessels, 
which send their blood into the portal vein. 
The lymphatics begin in the mucous membrane, and form a large plexus in the submucosa ; 
leaving the gut, those of the caecum, ascending, transverse, and upper half of the desce nding colon, 
pass to the mesocolic glands, which lie behind the ascending and descending divisions of the colon 
and between the layers of the transverse mesocolon. The lymphatics from the lower half of 
the descending, and from the iliac and pelvic colons, join the left lymphatic trunk of the lumbar 
glands. bose. of the rectum will be deseribed later. 
Nerves. — The nerves come from the superior mesenteric plexus, an offshoot of the solar 
plexus, and from the inferior mesenteric, 
a derivation of the aortic plexus. The 
arrangement is similar to that of the 
nerves of the small intestine. 
Anterior tenia coli 
Upper segment of 
7 ileo-colic valve 
Frenuluin of the 
valve 
THE CHCUM AND APPENDIX. 
After leaving the pelvic 
cavity, as already described, the Frenntum 
terminal portion of the small colic valve 
intestine passes upwards, back- 
wards, and to the right, and 
opens, by the ileo-ceecal orifice, 
into the large intestine some 24 
inches from its lower end. The 
en of the large gut which 
lies below the level of this orifice 
is known as the cecum (caput RoE By. < i 
eeecum coli). In shape (Fie. 69: 3) PIG: ie iictgeets SHOWING ILEO-CHCAL VALVE. . 
it is a wide, unsymmetrical, or The cecum has been distended with air and dried, and a portion 
: of its anterior wall has been removed. 
lop-sided cul-de-sac, furnished 
with the teniz and sacculations usually found in the large intestine. Its lower 
end or fundus is directed downwards and inwards, and usually rests on the front 
of the right psoas muscle, close to the brim of the pelvis; whilst the opposite 
end is directed upwards and outwards, and is continued into the ascending colon. 
-Orifice of valve 
Inferior 
segment 
Terminal 
vm part of ileum 
Teenie colit 
Orifice of appendix” 
Its unsymmetrical form is due to the fact that the outer and inner portions of the organ 
— undergo an unequal development in the child. The inner (or inner and posterior) section lags 
65 
