502 JEJUNUM ILEUM CAECUM. 



the liver and neck of the gall-bladder ; in front with the greater 

 omentum and abdominal parietes; and behind with the right border 

 of the lesser omentum and its vessels. The second or perpendicular 

 portion is situated altogether behind the 'peritoneum ; it is in rela- 

 tion by its anterior surface with the commencement of the arch of 

 the colon ; by its posterior surface with the concave margin of the 

 right kidney, the inferior vena cava, and the ductus communis 

 choledochus ; by its right border with the ascending colon : and by 

 its left border with the pancreas. The ductus communis choledo- 

 chus and pancreatic duct open into the internal and posterior side 

 of the perpendicular portion, a little below its middle. The third 

 or transverse portion of the duodenum lies between the diverging 

 layers of the transverse meso-colon, with which and with the 

 stomach it is in relation in front ; above it is in contact with the 

 lower border of the pancreas, the superior mesenteric artery and 

 portal vein being interposed ; and behind it rests upon the inferior 

 vena cava and the aorta. 



The Jejunum (jejunus, empty) is named from being generally 

 found empty. It forms the upper two-fifths of the small intestine ; 

 commencing at the duodenum on the left side of the second lumbar 

 vertebra, and terminating in the ileum. It is thicker to the touch 

 than the rest of the intestine, and has a pinkish tinge from contain- 

 ing more mucous membrane than the ileum. 



The Ileum (s'/Xeiv, to twist, to convolute) includes the remaining 

 three-fifths of the small intestine. It is somewhat smaller in calibre, 

 thinner in texture, and paler than the jejunum ; but there is no mark 

 by which to distinguish the termination of the one or the commence- 

 ment of the other. It terminates in the right iliac fossa, by opening 

 at an obtuse angle into the colon. 



The jejunum and ileum are surrounded above and at the sides by 

 the colon ; in front they are in relation with the omentum and abdo- 

 minal parietes ; they are retained in their position by the mesentery, 

 which connects them with the posterior wall of the abdomen ; and 

 below they descend into the cavity of the pelvis. At about the lower 

 third of the ileum a pouch-like process or diverticulum of the intes- 

 tine is occasionally seen. This is a remnant of embryonic structure, 

 and is formed by the obliteration of the vitelline duct at a short .dis- 

 tance from the cylinder of the intestine. 



Large intestine. The large intestine, about five feet in length, is 

 sacculated in appearance, and is divided into the ccecum, colon and 

 rectum. 



The CcBcum (ca3cus, blind) is the blind pouch, or cul-de-sac, at 

 the commencement of the large intestine. It is situated in the right 

 iliac fossa, and is retained in its place by the peritoneum, which 

 passes over its anterior surface ; its posterior surface is connected 

 by loose cellular tissue with the iliac fascia. Attached to its ex- 

 tremity is the appendix vermiformis, a long worm-shaped tube, the 

 rudiment of the lengthened caecum found in all mammiferous animals 

 except man and the higher quadrumana. The appendix varies in 





