Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 5: Supplementary Volume
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit36060/449/
379 
STOMACH AND INTESTINE. 
to allow of the much quicker destruction of 
their poisonous properties by a more or less 
perfect oxidation. 
Arteries of the intestines. — We have seen 
that the stomach and duodenum are supplied 
with arterial blood by means of various twigs 
derived from the three branches of the coeliac 
axis, which springs from the upper part of 
the abdominal aorta. The remainder of the 
intestinal canal is furnished with arteries which 
are given off by two large branches of the 
abdominal aorta. These branches are named, 
from their position and distribution, the 
superior and the inferior mesenteric. 
The superior mesenteric artery (a, fig. 277.), 
the longer of these two branches, is distributed 
over that large segment of the intestine which 
is formed by the lower part of the duodenum, 
the whole of the jejunum, ileum, and cæcum, 
and the first two-thirds of the colon. The 
Fig. 277. 
Distribution of tke superior mesenteric artery to the 
small and large intestine. 
a, trunk of the superior mesenteric artery ; b, ileo¬ 
colic artery ; c, its iliac branch ; d, its colic branch ; 
e, right colic artery ; f middle colic artery; g, 
arches formed by the anastomosis of the branches 
to the small intestine ; p, pancreas ; du, duodenum ; 
j, jejunum ; i, ileum ; c œ, cæcum; ac, ascending 
colon ; t c, transverse colon ; d c, descending colon. 
trunk of the vessel comes off from the aorta, 
at a point which about corresponds to the 
upper border of the second lumbar vertebra. 
It is separated from the coeliac axis by the 
pancreas ; and hence is distant about a third 
of an inch from the origin of the latter vessel. 
From this commencement, it passes down¬ 
wards and forwards, crossing over the termi¬ 
nation of the duodenum, so as to reach the 
upper part of the mesentery. It now con¬ 
tinues downwards between the two layers of 
this fold of peritoneum, which it occupies near 
its attachment to the posterior wall of the 
abdomen. Hence its length and direction 
correspond to those of the attached border of 
the mesentery itself ; and are such, as to 
conduct it downwards and obliquely towards 
the left side, to a termination that corresponds 
to the end of the ileum, or the commencement 
of the cæcum. But the branches given off to 
these latter segments of the intestine by the 
trunk of the vessel are so large, and so directly 
continuous with its previous course, that it is 
only in a very arbitrary and limited sense that 
we can speak of it as ending in this situation. 
The arrangement of the larger or primary 
branches of the superior mesenteric artery 
is liable to great variation, but is generally as 
follows. 
The trunk of the superior mesenteric artery 
is directly continuous with a large vessel (b, 
fig. 277.), which, when it has reached a dis¬ 
tance of about two inches from the cæcum, 
divides into two others ; of these the upper 
(d,fig• 277.)passes towards the cæcum,and the 
lower {c,fig. 277.) towards the ileum. Theileo- 
colic artery (b,fig. 277.), as the common trunk 
is named prior to its bifurcation, usually gives 
off from its right side one of rather smaller size, 
about three inches from the border of the bowel. 
The latter, which is called the arteria colica 
dextra, or right colic artery (e,fig. 277.), often 
arises by a separate trunk from the superior 
mesenteric. It takes a course almost horizon¬ 
tally outwards, or towards the right side, 
lying underneath the single layer of perito¬ 
neum which covers in the ascending colon, so 
as to reach this part of the large intestine at or 
near the middle of its height. Finally, at a dis¬ 
tance of little more than an inch from its 
entering the mesentery, the trunk of the supe¬ 
rior mesenteric artery gives off a large branch, 
the arteria colica media ( ffig. 277.), which 
passesupwards and backwards,enters between 
the two layers of the transverse meso-colon, 
and is distributed to the transverse colon, 
which it reaches at the middle of its posterior 
border. Besides these named branches, the 
superior mesenteric gives off numerous arte¬ 
ries (at g, fig. 277.), of almost equal size, 
which have not received any special designa¬ 
tion. These twenty or thirty branches leave 
the left side of the artery, at various points 
between the lower border of the duodenum 
and the origin of the ileo-colic artery ; and 
pass outwards, or to the left side, towards 
their distribution on the small intestine. 
The further course of all these branches 
towards the small and large intestine affords 
a remarkable , instance of an arterial ana¬ 
stomosis ; such as is almost unparalleled in 
the whole of the body for the freedom and 
frequency of its communications, and the 
size of the1!vessels by which they are effected. 
Each of the primary branches just alluded to 
bifurcates: and its two resulting branches 
unite with those above and below them, so 
as to form a set (g,fig. 277.) of arterial arches ; 
from the convexity of which spring new 
trunks, to divide and inosculate in a similar 
manner. This arrangement, which prevails
        

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