INTERIOR 457 



tensive chief pillars project like shelves into the anterior and posterior ends of the 

 cavity, forming the blind sacs at either extremity. The anterior pillar (Pila cranialis) 

 projects obliquely backward and 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 attached border is about eight to ten inches (ca. 20 

 to 25 cm.). It is continued on either side by the relatively narrow longitudinal 

 piUars^ (Pila dexter, sinister), 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 tuber cox^. 

 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 



Fig. 389. — Thoracic and Anterior Abdominal Viscera of Ox; Deep Dissection. '■ ' : ' 

 Most of the rumen has been removed and the left wall of the reticulum cut away. A., Left pulmonary artery; 

 B., left bronchus; V. V. V., pulmonary veins; h. h., bronchial lymph glands; L. g., posterior mediastinal lymph gland; 

 D., termination of duodenum; F, rumino-reticular fold^ 



mark off the posterior blind sacs from the general cavity, and are termed the 

 coronary pillars (Pila coronaria dorsalis, ventralis). 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, vi^hile 

 the dorsal one joins the posterior 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 communi- 

 cate freely. 



The anterior end of the dorsal sac of the rumen is separated ventrally from the 

 reticulum by an almost vertical fold formed by the apposition of the walls of the 

 two compartments. This rumino-reticular fold (Pila rumino-reticularis) is oppo- 

 site to the seventh or eighth rib.-^ Its free dorsal edge is concave and forms the 



' The position of this fold naturally varies with the degree of fulness of the reticulum. When 

 the latter is full, it may extend back in part to the eighth intercostal space. 



