BRANCHES OF THE ABDOMINAL AORTA 665 
Il. The anterior or great mesenteric artery 
(A. mesenterica cranialis) arises from the ventral 
face of the aorta at the first lumbar vertebra. It 
is a large unpaired trunk, about an inch (ca. 2-3 
em.) in length, which passes ventrally between the 
vena cava and the left adrenal into the root of 
the great mesentery, when it divides into three 
branches—left, right, and anterior." 
1. The left branch gives off at once about 
fifteen to twenty arteries of the small intestine 
(Aa. intestinales).? These come off close together 
and pass in divergent fashion between the layers 
of the great mesentery, each dividing into two 
branches which anastomose with adjacent branches 
to form a series of arches. In the anterior part of 
the series secondary arches are formed by the union 
of branches given off from the primary set of 
arches. From the convex side of these arches 
terminal branches pass to the wall of the small 
intestine, in which they ramify and form a vascu- 
lar network. They are accompanied by satellite 
veins and by nerves and lymph vessels. The first 
artery anastomoses with the pancreatico-duodenal, 
and the last with the ileal branch of the great 
mesenteric artery. Branches are supplied to the 
mesenteric lymph glands. 
2. The right branch (A. ileo-cxco-colica) 
might be regarded as the continuation of the 
trunk. It runs downward and a little forward 
and to the right, and gives off the ileal, the two 
cecal, and the ventral colic arteries. (1) The 
ileal or ileo-cxcal artery (A. ilea) passes in retro- 
is; 29, saphenous. 
Is are ventral 
AND Mepran Surnrac 
or mesenteric; 9, arteries of small in 
26, deep femoral; 27, anterior femoral; 28, branch to graci 
iliac glands; d, external iliac glands; e, prefemoral glands; /, deep inguinal glands (position indicated by dotted 
reumflex iliac; 17, 19, anterior and posterior bran 
; 6,7, renal; 8, ante 
artery. Besides numerous collaterals to the cecum, 
it gives off the artery of the arch, which passes 
along the lesser curvature of the base of the cecum 
and runs on the lateral face of the origin of the 
great colon. (3) The medial cecal artery (Ramus 
cxcalis medialis) passes along the medial band to 
the apex of the cecum, where it anastomoses with 
the lateral cecal artery. (4) The ventral colic 
= ee: grade fashion along the terminal part of the ileum 
Ss S and unites with the last branch of the left division. 
23. 2 (2) The lateral cecal artery (Ramus cxcalis later- 
Z25 cS alis) passes between the czecum and the origin of 
eS = F the colon andruns on the lateral band of the cecum 
cas = to the apex, where it anastomoses with the medial 
gee a 
2 
Via, 575,—Dissuetion or Sustumpar Rearon, Pwryic INLe 
fem. 
14, exte 
altz, Atlas d, Anat. d. Pferdes,) 
vena cava; 
a, Lymph-vessels; b, lumbar glands; c, internal 
osus; JK, suspensory lig, 
1 Jn the great majority of subjects this vessel and some 
of its branches are the seat of more or less extensive vermin- 
ous aneurysm, produced by the Sclerostomum vulgare. 
In the author's experience an entirely normal specimen is 
quite unlikely to be encountered except in very young foals. 
2 The left branch is a descriptive convention rather 
than a reality, since the arteries of the small intestine spring 
from the mesenteric trunk either directly or by short com- 
mon stems with an adjacent vessel. 
1, Aorte 
13, posterior mesent 
Lymph-vessels and glands: 
line). 
Nerves and ganglia: 
Blood-vessels: 
of small colon 
21, cremasteric; 22, lateral sacral; 23, internal pudic; 
brane nes of external spe 
at hiatus a 
(After Sct 
