THE SMALL INTESTINE 419 



cation exist. A narrow zone next to the margo plicatus has a yellowish-gray color, 

 and contains short tubular cardiac glands (cardiac gland region) . Next to this is a 

 large area which has a mottled, reddish-brown color, aiid, contains fundus glands 

 (fundus gland region) ; these glands have two distinct types of cells. This part of 

 the mucous membrane is thick and very vasc.ular, 'and corresponds to the fundus 

 of the stomach in man and the dog. The remainder of the mucous membrane is 

 thinner, has a reddish-gray or yellowish-gray color, and contains pyloric glands, 

 which have a single type of cells corresponding to the chief cells of the fundus glands 

 (pyloric gland region); it corresponds to the pyloric portion of man and the dog. 

 The folding of the stomach wall at the lesser curvature produces a prominent 

 ridge which projects into,. the cavity of the stomach. The circular fold which 

 covers the pyloric sphincter is termed the pyloric valve (Valvula pylori) . 



The CESophageal part constitutes one third to two-fifths of the mucous membrane. The 

 cardiac gland region is extremely narrow (ca. 0..5 to 1 mm . ) at the greater curvature, but becomes about 

 an inch wide toward, the pyloric part. Since the majority of the glands here are not typical 

 cardiac glands, hke those of the pig and other animals, but are intermediate in type between these 

 and pyloric glands, the term intermediate zone might well be used.- 



Vessels and Nerves. — The stomach receives blood from all the branches of 

 the cceliac artery. The gastric veins drain iiito the portal vein. The lymph 

 vessels go chiefly to the gastric lymph glands, thence to the cisterna chyli. The 

 nerves are derived from the vagus and sjntnpathetic nerves. 



THE SMALL INTESTINE 



The small intestine (Intestinum tenue) is the tube which connects the stomach 

 with the large intestine. It begins at the pylorus and terminates at the lesser 

 curvature of the caecum. Its average length is about seventy feet (ca. 22 meters), 

 and when distended its diameter varies from three to four inches (7.5 to 10 cm.). 

 Its capacity is about twelve gallons (40 to 50 liters). 



It is clearly divisible into a fixed and a mesenteric part. The fixed part is 

 termed the duodenum, while the mesenteric part (Intestinum tenue mesenteriale) 

 is arbitrarily divided into parts termed the jejunum and ileum. ^ 



The duodenum is about three to four feet (ca. 1 m.) long. Its shape is 

 somewhat like a horseshoe, the convexity being directed toward the right. The 

 first part (Pars prima duodeni) is directed to the right and forms an po-shaped 

 curve. The convexity of the first part of the curve is dorsal, of the second, ventral. 

 It is in contact with the middle and right lobes of the liver, and presents two am- 

 pullse with a constriction between them. The duodenal angle (or head) of the 

 pancreas is attached to the concavity of the second curve, and here, five to six 

 inches (ca. 12 to 15 cm.) from the pylorus, the pancreatic duct and the bile duct 

 pierce the bowel wall. The second part (Pars secunda duodeni) passes upward 

 and backward on the right dorsal part of the colon and ventral to the right lobe of 

 the liver, and, on reaching the right kidney and the base of the caecum, it curves 

 toward the median plane, opposite the last rib. The third part (Pars tertia duo- 

 deni) passes from right to left behind the attachment of the base of the cacum, 

 crosses the median plane behind the root of the great mesentery, and turns forward 

 to become continuous with the mesenteric part under the left kidney .^ The sac- 

 culations of the first part have a diameter of three to four inches (ca. 7.5 to 10 cm.). 

 It is attached by a short peritoneal fold termed the mesoduodenum. This fixes 



1 No natural line of demarcation exists, but there is a marked increase of the thickness of 

 the wall toward the terminal part. Other differences will be noted in the further description. 



2 The duodenum commonly curves around the periphery of the right kidney, from which it 

 is separated by the base of the cfficum, but in some cases it is in contact with the ventral surface 

 of the kidney. It may cross the median plane ventral to the second lumbar vertebra or further 

 back, depending apparently on the fulness of the csecum. 



