THORAX AND ABDOMEN OF THE HORSE 115 



flexure of the larger colon, and is only slightly ventral to the mid-point 

 of the dorso-ventral diameter of the abdominal cavity. Thus the 

 stomach, when moderately distended, is at some distance from the 

 ventral wall of the abdomen. Distension, moreover, does not cause the 

 stomach to approach the abdominal wall to any great extent, but rather 

 causes the organ to bulge towards the pelvis. 



The left extremity (extremitas sinistra) of the stomach is formed 

 by the saccus c?ecus. The right extremity (extremitas dextra) is more 

 ventral in position and is formed by the jiylorus ^ and the antrum pylori. 

 The antrum is the small part of the stomach preceding the pylorus, 

 and is marked off by two constrictions which correspond to thickenings 

 of the circular stratum of the muscular tunic. The thickening to the 

 right, that is the one encircling the pylorus, is the true "pyloric sphincter 

 (sphincter pylori). The pylorus, leading into the duodenum, is about 

 5 or 6 centimetres ventral to the cardia, immediately to the right 

 of the median pkiue, and in contact with the liver close to the porta. 



The two surfaces of the stomach are smooth and convex and covered 

 by peritoneum. The cranial or parietal surface (facies parietalis) is in 

 contact with the diaphragm and liver, and is so inclined as to look in a 

 cranial and dorsal direction and towards the left. The caudal or visceral 

 surface (facies visceralis) has a correspondingly oblique aspect, and is 

 related to the small intestine, the small colon, the terminal part of the 

 large colon, the pancreas and the greater omentum. 



Apart from the fixation afforded by the oesophagus, the stomach 

 depends upon the peritoneum for its connection with surrounding 

 structures. The gastro-phrenic"^ ligament (ligamentum gastro- 

 phrenicum) passes from the region of the cardia and the immediately 

 adjacent part of the greater curvature to the neighbouring part of the 

 diaphragm. A narrow triangular area of the stomach is here left 

 uncovered by peritoneum, with the result that loose connective tissue 

 alone intervenes between the stomach and the diaphragm. The gastvo- 

 splenic ligament (ligamentum gastrolienale), which may be regarded as 

 part of the greater omentum, passes from the greater curvature to the 

 hilus of the spleen. Dorsally it is continuous with the phrenico-splenic 

 ligament, and thus the saccus csecus of the stomach is suspended from 

 the left lumbar part of the diaphragm. The gastro-hepatic ligament 

 (ligamentum gastrohepaticum) leaves the lesser curvature of the 

 stomach and is attached to the central lobe of the liver. To the 

 right it is continuous with the hepato-duodenal ligament : the two 

 together forming the lesser omentum. The gastro-jxincreatic fold 



' TTvXupoi (pyloros) [Gr.], a gatekeeper. 

 - (pp-qv (pbrCn) [Gr.], the diaphragm, heart, seat of the emotions. 



