98 TOPOGRAPHICAL ANATOMY OF THE 



difficult to recognise, because, for a metre or more before the caicuni is 

 reached, the wall of this part of the small intestine is definitely thicker. 

 A considerable part of the ileum lies to the right of the median plane. 



The duodenum, being much less mobile than the rest of the small 

 intestine, has a definite position in relation to the liver and the right 

 kidney. The examination of this portion of the intestine is best 

 deferred until later. 



The large intestine (Intestinum crassum). — There can be little 

 question that the large intestine of the horse merits its name, for the 

 greater part of the tube is of a calibre many times that of the small 

 intestine. Another striking feature of this part of the alimentary tube 

 is the presence of numerous sacculations (haustra) ^ produced by 

 longitudinal bands or flattened bundles (tcenise) ^ of muscular fibres. 

 The bands being shorter than the gut of which they form part, it 

 follows that the surface of the tube cannot be smooth, as it is in the 

 small intestine where muscular bands are absent. 



The large intestine is divided into three clearly differentiated 

 portions — the caecum, the colon and the rectum. 



The CCBCU771 ^ (intestinum caecum). — The greater part of the large 

 conical caecum occupies the right dorsal region of the abdomen, the 

 basal extremity of the tube being close to the inlet to the pelvis. The 

 narrower part of the caecum extends along the floor of the abdomen 

 with some small degree of obliquity, so that the blind, pointed cranial 

 end is ventral in position and generally at, or possibly slightly to the 

 left of, the median plane, a short distance behind the xiphoid process of 

 the sternum. 



It is convenient to consider the caecum as composed of a body, a 

 dorsal sac and an apex. The body (corpus caeci) is the middle part 

 of the tube and gradually tapers to the blind, pointed cqjex (apex 

 caeci). It will be observed that the apex is freely movable. 



The dorsal sac (saccus dorsalis caeci) is the most capacious, as well 

 as the most caudal and dorsal, part of the caecum. Its form is such as 

 to permit of the ready recognition of two curvatures. The greater 

 curvature (curvatura major) is convex, and is in contact with and 

 adherent to the right kidney and the pancreas. The concave lesser 

 curvature (curvatura minor) has a ventral and medial aspect. The 

 cranial end of the dorsal sac is blind ; while the caudal or pelvic end is 

 continuous with the body of the caecum. To the right the sac is in 

 contact with the duodenum ; its left face being related to the jejunum, 



1 Haustrum [L.], a machine for drawing up water from a well, a drawer. 



2 Trenia [L.], raivla (tainia) [Gr.], a flat band, a tape, a ribbon. 

 ^ Ccecus [L.], blind. 



