INTERIOR 



461 



(parietal) face of the omasum and the pyloric part of the abomasum and the first 

 part of the duodenum. What might be regarded as a connection between the 

 omenta is a fold between the ventral curvature of the omasum and the dorsal 

 curvature of the abomasum. 



The greater omentum conceals the greater part of the intestine on the right 

 side, mth the exception of the duodenum, and covers the ventral sac of the rumen 

 almost entirely. It is not lace-like, as in the horse, and contains a large amount 

 of fat in animals in good condition. It may be described as consisting of two 

 parts, each of which is composed of two layers of peritoneum ; the two serous layers 

 enclose a variable amount of fat. The superficial part extends from the left 

 groove of the riunen ventrally around the ventral sac and ascends on the right 

 side, covering the deep part. It ends along the retrograde part of the duodenum 

 and the greater curvature of the abomasum. The deep part is attached along the 

 visceral (right) surface of the rumen ventral to the right groove, and curves around 

 the intestinal mass to the right side, where it is covered by the superficial part. It 



Fig. 393. — Interiob of Abomasum of Ox. 

 F, Fundus gland region with large spiral folds; P, pyloric region; D, duodenum; 1, pylorua; 2, torus pyloricus. 



ends chiefly by blending with the medial layer of the mesoduodenum, but anter- 

 iorly is attached on the first bend of the colon and the visceral surface of the liver 

 along the ventral border of the pancreas. The two parts are continuous at the 

 posterior groove of the riunen. They also join at the iliac flexure of the duodenum 

 and at the origin of the colon. The epiploic foramen is almost sagittal in direc- 



The muscular coat of the rumen consists of two layers. The fibers of the 

 external layer are in general longitudinal; those of the thicker internal layer are 

 largely circular in direction. The latter forms the bulk of the chief pillars, where 

 it is about one-half to one inch (ca. 1 to 2 cm.) thick. Scattered bundles of striped 

 muscle-fibers radiate from the cardia in the wall of the atrium and extend also along 

 the oesophageal groove. 



The arrangement is in fact by no means so simple as might be inferred from the above brief 

 statement, and much variation from the typical disposition is present. Along the turrows the 

 fibers of the external layer are disposed more or less obhquely or even vertically m part; a super- 

 ficial Dart of the layer bridges over the furrows (with the fat and vessels contamed therem), while 

 the deeper fibers extend into the pillars. The fibers of the inner layer on approaching the furrows 

 change to an oblique or even horizontal direction. On entering the chief pillars this layer becomes 



