470 



DIGESTIVE SYSTEM OF THE SHEEP 



The right or posterior part is wide and thin and is often divided into two branches. 

 The duct leaves the posterior part of the ventro-lateral (or right) border and enters 

 the duodenum about twelve inches (ca. 30 cm.) further back than the bile-duct. 



Splenic vein 

 Splenic artery 

 Hilus 



THE SPLEEN 



The spleen has an elongated, elliptical outline, both extremities being thin, 



rounded, and similar in size. 



Its average weight is about two pounds (ca. 900 gm.), or about K per cent, of 



the body- weight. Its average length is about 20 inches (ca. 50 cm.), its width 



about 6 inches (ca. 15 cm.), and in the 

 Dorsal extremity middle its thickness is about an inch (ca. 



2 to 3 cm.). 



The dorsal extremity lies under the 

 dorsal ends of the last two ribs, and may 

 extend l^ack as far as the first lumbar 

 transverse process. The ventral extrem- 

 ity is usually opposite the eighth or ninth 

 rib, about a handbreadth above its junc- 

 tion with the cartilage. The parietal sur- 

 face is convex, and is related to the dia- 

 phragm. The visceral surface is concave, 

 and is related chiefly to the left face of the 

 rumen, but also usually to a narrow ad- 

 jacent area of the reticulum. The dorsal 

 part is attached to the left crus of the dia- 

 phragm and the left surface of the rumen 

 by peritoneum and connective tissue ; the 

 ventral part is free. The hilus is situated 

 on the dorsal third of the visceral surface, 

 near the anterior border. 



About one-half of the visceral surface of the 

 spleen is attached directly to the stomach and is 

 therefore not covered by peritoneum ; the line of re- 

 flection of the latter crosses the surface obhquely, 

 from the upper part of the posterior border to 

 the anterior border below its middle. Similarly 

 there is a narrow uncovered area on the upper 

 part of the parietal surface along the anterior 

 border. The hilus is not a groove, but a simple 

 depression. When hardened in situ, the organ is 

 seen to be somewhat twisted, so that the upper 

 part of the parietal surface faces dorsally and 

 forward, while below it is directed laterally. In 

 some cases the spleen is considerably longer than 

 is stated above, and may extend to the ventral end of the eighth rib. Not uncommonly there are 

 pathological adhesions of the ventral part of the spleen to adjacent structures. 



2 — 



Ventral exlremity 

 Fig. 403. — Spleen- of Ox; Viscebal Surface. 

 1, Area of attachment to rumen (non-peritoneal); 

 posterior border; 3, line of peritoneal reflection. 



DIGESTIVE SYSTEM OF THE SHEEP 



The lips are thin and mobile; the upper one is marked by a very distinct 

 philtrum, and otherwise is not bare. 



The anterior part of the hard palate is prominent and smooth, forming the 

 so-called dental pad or plate. On the posterior part of this area there are two 



