734 A MANUAL OF ANATOMY 



Posterior. — ^The inferior vena cava, right crus of the diaphragm, 

 aorta, and left renal vein. Superior. — The first part of the duo- 

 denum. Inferior. — ^The third part of the duodenum, and the inferior 

 pancreatico-duodenal artery. Right. — The second part of the 

 duodenum, with the common bile-duct behind, as low as a little below 

 the centre, and the superior pancreatico-duodenal artery in front. 



The neck may be defined as the part in front of the origin of 

 the vena portae and the termination of the superior mesenteric vein. 

 It springs from the anterior surface of the head near its upper part, 

 and is about i inch in length. Its direction is upwards and to the 

 left, and it forms the connecting link between the head and body. 

 The gastro-duodenal and superior pancreatico-duodenal arteries 

 occupy a groove on its right side, and the commencement of the first 

 part of the duodenum is in front of it, whilst the origin of the vena 

 portae and the termination of the superior mesenteric vein are 

 behind it. 



The body passes to the left, with a slight inclination backwards 

 after it has crossed the aorta. It is triangular, and presents three 

 surfaces — antero-superior, posterior, and inferior, and three borders 

 — superior, anterior, and posterior. 



The antero-superior surface, which is covered by peritoneum, is 

 in relation with the posterior surface of the stomach. At its right 

 extremity, just below the coeliac axis, it presents a prominence, 

 called the omental tuberosity from its relation to the gastro-hepatic 

 omentum. The posterior surface, which is destitute of peritoneum, is 

 related to the following structures : the aorta below the coeliac axis, 

 with a portion of the solar plexus ; the origin of the superior mesen- 

 teric artery ; the left suprarenal capsule ; and the left kidney with 

 its vessels. The splenic vein passes from left to right in contact with 

 this surface near the superior border. The inferior surface, which 

 is covered by peritoneum, is moulded on the duodeno-jejunal flexure, 

 some coils of the jejunum, and the left extremity of the transverse 

 colon. The coeliac axis projects forwards over the superior border 

 above the omental tuberosity. To the left of this axis the splenic 

 artery pursues its tortuous course to the spleen, and to the right of 

 it the hepatic artery lies for a short distance. The transverse meso- > 

 colon is attached to the anterior border along which its separation 

 into ascending and • descending layers takes place, the former 

 covering the antero-superior surface of the organ, and the latter, 

 on its way backwards, investing the inferior surface. The posterior 

 border presents nothing noteworthy. 



The tail corresponds with the left extremity where the pancreas 

 is narrowest, and is in contact with the lower end of the gastric 

 surface of the spleen behind the hilum. 



For the structure and development of the pancreas, see pp. 8og, 812. 



Solar or Epigastric Plexus of the Sympathetic System. — The solar 

 plexus is of large size, and is situated deeply in the epigastric 

 region, behind the stomach and in front of the crura of the 

 diaphragm and the aorta close to the origins of the coeliac axis and 



