442 



DIGESTIVE SYSTEM OF THE HORSE 



the epiploic foramen (Foramen epiploicum).i 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 hver 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 

 cavity 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 bursaj omentalis). This space is 



Fig. 377. — Diagram of General Arrangement oi' Peritoneum (op Mare) in Sagittal Tracing. 



, Sacro-rectal pouch, continuous -with b, recto-genital pouch; c, vesico-genital pouch; d, pubo-vesical pouch; /, lesser 



omentum; Int., 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 (Eso- 

 phageal notch there is a recess, into which the fingers can be passed around the 

 border of the hver 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 omentimi has already been indicated. 

 We may now trace its line of attachment, which would correspond to the mouth of 

 the sac. Begiiming 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- 

 versely (from right to left), and continues for some ten or twelve inches (ca. 25 



' Also known as the foramen of Winslow. 



^ The passage is subject to a good deal of variation in cahber and is sometimes occluded. 



