THE LIVER. 515 



The Stomach is completely surrounded by peritoneum, excepting along 

 the line of junction of the great and lesser omentum. The first or oblique 

 portion of the duodenum is also completely included by the serous mem- 

 brane, with the exception of the points of attachment of the omenta. The 

 descending portion has merely a partial covering on its anterior surface. 

 The transverse portion is also behind the peritoneum, being situated be- 

 tween the two layers of the transverse meso-colon, and has but a partial 

 covering. The rest of the small intestine is completely invested by it, 

 excepting along the concave border to which the mesentery is attached. 

 The ccBcum is more or less invested by the peritoneum, the more frequent 

 disposition being that in which the intestine is surrounded for three-fourths 

 only of its circumference. The ascending and the descending colon are 

 covered by the serous membrane only in front. The transverse colon is 

 invested completely, with the exception of the lines of attachment of the 

 greater omentum and transverse meso-colon. And the sigmoid flexure is 

 entirely surrounded, with the exception of the part corresponding with the 

 junction of the left meso-colon. The upper third of the rectum is com- 

 pletely enclosed by the peritoneum ; the middle third has an anterior 

 covering only, and the inferior third none whatsoever. 



Vessels and Nerves. The Arteries of the alimentary canal, as they 

 supply the tube from above downwards, are the pterygo-palatine, ascend- 

 ing pharyngeal, superior thyroid, and inferior thyroid, in the neck ; oeso- 

 phageal, in the thorax ; gastric, hepatic, splenic, superior and inferior 

 mesenteric, in the abdomen; and inferior mesenteric, iliac, and internal 

 pudic, in the pelvis. The veins from the abdominal alimentery canal 

 unite to form the vena portaa. The lymphatics and lacteals open into the 

 thoracic duct. 



The Nerves of the pharynx and oesophagus are derived from the glosso- 

 pharyngeal, pneumogastric, and sympathetic. The nerves of the stomach 

 are the pneumogastric, and sympathetic branches from the solar plexus ; 

 and those of the intestinal canal are the superior and inferior mesenteric 

 and hypogastric plexuses. The extremity of the rectum is supplied by 

 the inferior sacral nerves from the spinal cord. 



THE LIVER. 



THE liver is a conglomerate gland of large size, appended to the ali- 

 mentary canal, and performing the double office of separating impurities 

 from the venous blood of the chylo-poietic viscera previously to its return 

 into the general venous circulation, and of secreting a fluid necessary to 

 chylification, the bile. It is the largest organ in the body, weighing about 

 four pounds, and measuring through its longest diameter about twelve 

 inches. It is situated in the right hypochondriac region, and extends 

 across the epigastrium into the left hypochondriac, frequently reaching, by 

 its left extremity, the upper end of the spleen. It is placed obliquely in 

 the abdomen ; its convex surface looking upwards and forwards, and the 

 concave downwards and backwards. The anterior border is sharp and 

 free, and marked by a deep notch, and the posterior rounded and broad. 

 It is in relation, superiorly and posteriorly, with the diaphragm ; and infe- 

 riorly, with the stomach, ascending portion of the duodenum, transverse 

 colon, right supra-renal capsule, and right kidney ; and corresponds, by 

 its free border, with the lower margin of the ribs. 



