442 DIGESTIVE SYSTEM OF THE HORSE 
the epiploic foramen (Foramen epiploicum).' This opening is situated on the 
visceral surface of the liver dorsal to the portal fissure. It can be entered by passing 
the finger along the caudate lobe of the liver toward its root. Its dorsal wall is 
formed by the caudate lobe and the posterior vena cava. Its ventral wall consists 
of the pancreas, the gastro-pancreatic fold, and the portal vein. The walls are 
normally in contact, and the passage ’merely a potential one. It is usually about 
four inches (ca. 10 cm.) in length. It is narrowest at the lateral extremity, where 
it is about an inch (ca. 2.5 to 3 cm.) wide.” If the finger is passed into the foramen 
from right to left, it enters the cavity of the lesser sac. If now an opening is made 
in the great omentum and the other hand introduced through it, the fingers of the 
two hands can touch each other over the lesser curvature of the stomach. The 
formation and boundaries of the lesser sac should now be examined by spreading 
out the great omentum. It will be found that the latter now encloses a considerable 
vavity behind the stomach; this is termed the omental cavity (Bursa omentalis). 
Passing forward over the lesser curvature of the stomach, we enter another space, 
the vestibule of the omental cavity (Vestibulum bursze omentalis). This space is 
—— = — >) . 
a : Reel m | 
: ag 
hia 
Fic. 377.—D1acram or GENERAL ARRANGEMENT OF PERITONEUM (OF MARE) IN SAGITTAL TRACING. 
a, Sacro-rectal pouch, continuous with 6, recto-genital pouch; c, vesico-genital pouch; d, pubo-vesical pouch; /f, lesser 
: ; ene i 
omentum; Jnt., small intestine. The arrow points to the epiploic foramen. 
closed on the left by the gastro-phrenic ligament, ventrally and on the right by 
the lesser omentum, and dorsally by the gastro-pancreatic fold, which is attached 
to the dorsal border of the liver and to the posterior vena cava. Above the ceso- 
phageal notch there is a recess, into which the fingers can be passed around the 
border of the liver and the vena cava till the coronary ligament is encountered. 
Thus the vestibule is closed except—(1) on the right, where it communicates with 
the cavity of the greater sac by the epiploic foramen; and (2) behind, where it 
communicates with the cavity of the omentum. 
The general arrangement of the greater omentum has already been indicated. 
We may now trace its line of attachment, which would correspond to the mouth of 
the sac. Beginning at the ventral part of the greater curvature of the stomach, it 
passes to the ventral face of the pylorus, then crosses obliquely the first part of 
the duodenum to the point where the pancreas is adherent to it. Here it passes 
to the anterior face of the terminal part of the great colon, runs along this trans- 
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versely (from right to left), and continues for some ten or twelve inches (ca. 2¢ 
1 Also known as the foramen of Winslow. 
* The passage is subject to a good deal of variation in caliber and is sometimes occluded. 
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