THE INTESTINES 1375 



right dome (Hertz). The pressure thus exerted on the heart accounts for the dyspnoea and 

 cardiac pain so often associated with flatulence. The position of the pyloric sphincter is shown 

 on the outer siu-face by a very constant venous ring runriing toward both lesser and greater 

 curvatures in the subserous layer at right angles to the long axis of the pyloric canal (Mo3'nihan). 



In connection with the extravasation of contents that results from perforating ujcers of the 

 stomach, a knowledge of the subphrenic peritoneal fossa? is important (p. 1372). Perforation 

 is rare on the posterior surface since it is less mobile than the anterior, and protective adhesions 

 form readily. When it does occur, extravasation into the omental bursa results, and such a 

 perforation is exposed by turning up transverse colon and stomach and incising the transverse 

 meso-colon. Perforation on the anterior surface usually gives rise to general peritonitis, but in 

 the less serious cases an abscess may form localised to (1) the right subphrenic space, (2) the 

 subhepatic fossa, or (3) the left subphrenic space, according to the situation of the ulcer on the 

 stomach. 



The spleen (fig. 1127; see also figures in Sections IX and XII). — This lies very 

 obliquely in the left hypochondrium, its long axis corresponds closely with the line 

 of the tenth rib. It is placed opposite the ninth, tenth, and eleventh ribs exter- 

 nally, being separated from these by the diaphragm; and medially it is connected 

 with the great end of the stomach. Below, it overlaps slightly the lateral border 

 of the left kidney (fig. 1127). Its highest point is on a level with the spine of 

 the ninth thoracic, and its lowest with that of the eleventh thoracic vertebra. 

 Its upper pole is distant about 3.7 (1| in.) from the median plane of the body, and 

 its lower pole about reaches the mid-axillary line on the same rib. (Godlee.) 

 In the natural condition it cannot be felt; but if enlarged, its notched anterior 

 margin extends do\\Tiward toward the umbilicus, and is both characteristic and 

 readily felt. 



The pancreas. — The head of the pancreas lies in the hollow formed by the 

 three parts of the duodenum, on the bodies of the second and third lumbar 

 vertebrae. The inferior vena cava lies behind it. The neck, body, and tail of 

 the pancreas pass obliquely to the left and slightly upward, crossing respectively 

 the commencement of the portal vein, the aorta, and the left kidney. The root 

 of the transverse mesocolon is attached to the anterior margin of the gland, so 

 that its supero-anterior surface is related to the omental bursa, and its inferior 

 surface to the greater sac. The importance of this relation in the formation 

 of pancreatic pseudo-cysts has been referred to above. 



Pancreatic ducts. — The main duct, the duct of Wirsung, opens into the common ampulla of 

 Vater with the bile duct. This ampulla usually opens into the gut by a narrow orifice raised 

 on a small papilla. A gall-stone impacted in the ampulla may cause a flow of bile backward 

 along the duct of Wirsung, and so give rise to acute pancreatitis (Opie). The small accessory 

 duct of Santorini opens into the duodenum independently about 2 cm. higher up. It often 

 anastomoses with the larger duct in the substance of the gland. 



Accessory nodules of pancreatic tissue are occasionally met with in the walls of the stomach 

 or small intestine at different regions. 



A cyst originating in the pancreas may "point" toward the anterior abdominal wall by 

 three routes: — (1) Above the stomach through the lesser omentum; (2) between stomach and 

 transverse colon through the great omentum; (3) below the transverse colon through the trans- 

 verse mesocolon. The posterior aspect of the head of the gland, with the third part of the 

 common bile duct may be exposed by incising the peritoneum on the lateral margin of the second 

 part of the duodenum, and turning the gut medially toward the middle line. 



Intestines. (A) Small. — The average length of the small intestine is about 

 6.85 m. (22| ft.), though the length as measured jjost mortem varies considerably 

 with the degree of contraction of the longitudinal muscular coat. The duodenum 

 is about 25 cm, (10 in.) in length. Of the remaining portion the upper two-fifths 

 constitute the jejunum and the lower three-fifths the ileum, though this division 

 is quite arbitrary. Cases are recorded in which patients have survived the re- 

 moval of over 5 m. (16 ft.) of small intestine. 



The first part of the duodenum extends from the pylorus on the first or second lumbar ver- 

 tebra, backward and to the right. It ends near the upper pole of the right kidney and on the 

 medial side of the neck of the gall-bladder, by turning down to form the less mobile second part, 

 which descends in front of the hilum of the right kidney to the level of the thii-d lumbar vertebra. 

 The third part of the duodenum crosses the body of the thu'd lumbar vertebra horizontally in 

 the infracostal plane, and then tm-ns up obliquely to the left side of the spine and ends at the 

 level of the upper border of the second lumbar vertebra in the duodeno-jejunal flexm-e. The 

 first part is the most mobile, since it is covered back and front by peritoneum in the first half 

 of its coiuse. The second part has a peritoneal covering in front only and is devoid of it where 

 it is crossed by the commencing transverse colon. The thii'd part is covered by peritoneum 

 in front except where the superior mesenteric vessels pass across it to join the commencement of 

 the mesentery. It is probably the constricting effect of these vessels on the duodenum that 

 gives rise to the acute dilatation of the stomach which occasionally follows abdominal operations. 



