THE STOMACH 393 



five inches (ca. 10 to 12 cm.) from the anterior extremity of the abomasum. The 

 ventral (greater) curvature is convex, and rests on the abdominal wall from the 

 xiphoid cartilage to the ventral part of the last (right) intercostal space. The 

 anterior extremity forms a rounded blind sac which lies against the reticulum. 

 The posterior (or pyloric) extremity is much smaller and bends upward and forward 

 to join the duodenum. About six to eight inches (ca. 15 to 20 cm.) from 

 the pylorus is a constriction which marks off the pyloric portion from the fundus. 



The rumen is attached by peritoneum and connective tissue to the crura of 

 the diaphragm and left psoas muscles, from the hiatus oesophageus backward to 

 about the third or fourth lumbar vertebra. 



The lesser omentum attaches the right face of the omasum and the pyloric 

 portion of the abomasum to the visceral surface of the liver. 



A small area of the anterior part of the right face of the rumen is adherent to 

 the adjacent surface of the abomasum. The greater part of the ventral curvature 

 of the omasum is attached by connective tissue to the dorsal face of the abomasum. 



(Adhesion of the reticulum to the diaphragm is frequently present, but is 

 pathological; the same is true in regard to adhesion to the liver.) 



Interior 



The cavity of the rumen is partially divided into dorsal and ventral sacs by 

 the pillars; these are folds of the wall, strengthened by additional muscular fibers, 

 and correspond with the grooves on the outside. The two most extensive ones 

 project like shelves into the anterior and posterior ends of the cavity forming the 

 blind sacs at either extremity; they are termed the chief pillars. The anterior 

 chief pillar (Pila cranialis) projc^cts obliquely backward antl upward from the ventral 

 wall, and has a thick concave free edge which is opposite to the tenth and eleventh 

 ribs. Its width from the middle of the free edge to its anterior border is about 

 eight to ten inches (ca. 20 to 25 cm.). It is continued on either side by the rela- 

 tively narrow longitudinal pillars, which connect it with the posterior pillar. The 

 posterior pillar (Pila caudalis) is more nearly horizontal than the anterior one, and 

 separates the large dorsal and ventral posterior blind sacs. Its concave free border 

 is about a hand's breadth in front of a transverse plane through the external angles 

 of the ilia. From it are detached three accessory pillars on either side; of these, 

 two pass around the blind sacs to meet the corresponding pillars of the opposite 

 side. They thus mark off the posterior blind sacs from the general cavity, and are 

 termed the coronary pillars. It will be noticed that the ventral coronary pillar is 

 complete, while the dorsal one is not. The other accessory pillars join the right 

 and left longitudinal pillars. The right longitudinal pillar is in part double; 

 its ventral division fades out about the middle of the surface, while the dorsal one 

 joins the posterior chief pillar. The distance between the middles of the anterior 

 and posterior pillars is only about sixteen to eighteen inches (ca. 40 to 45 cm.) in 

 a cow of medium size. In this space the dorsal and ventral sacs communicate 

 freely. 



The anterior dorsal blind sac of the rumen is separated from the reticulum 

 by an almost vertical fold formed by the apposition of the walls of the two compart- 

 ments. This rumino-reticular fold (Pila rumino-reticularis) is opposite to the 

 seventh rib and intercostal space. Its free upper edge is concave and forms the 

 lower and outer margin of the large, oval rumino-reticular orifice (Ostium rumino- 

 reticulare). The inner margin of the fold if continued would end about at the 

 cardia, but there is in this region no demarcation between rumen and reticulum; 

 hence it is termed the atrium ventriculi or vestibule. 



If the rumino-reticular fold and an imaginary completion of it be taken as the boundary 

 between the rumen and reticulum, it will be seen that the cardia belongs to the latter. The 

 outer border of the rumino-reticular fold ends above and behind the cardia, the inner one just 



