THORAX AND ABDOMEN OF THE HORSE 99 



small colon, the right dorsal colon, and, frequently, the pelvic flexure of 

 the great colon. 



The lesser curvature of the dorsal sac is connected with the ileum 

 and the colon. The termination of the ileum is surrounded by a strong 

 ring of muscular fibres (sphincter ilei) that gives sharp definition to 

 the mergence of the small intestine into the caecum. The connection 

 of the ceecum and colon, while sufficiently definite, is not so narrow as 

 the ileo-csecal junction. The cseco-colic union, moreover, is lateral to 

 (that is, to the right of) and somewhat nearer the pelvic brim than is the 

 entrance of the ileum into the caecum. It also is provided with a ring 

 of muscular fibres (sphincter ca3ci). 



Ileum 



Ileo-csecal fold. 



Body of caecum. 



Taenia (medial). 



Dorsal sac of caecum. W /v\ X\v— ^^ ~^^>-^^J.lW>' 



Right ventral colon.'\ ^ ^ \ ^P^^ o^ z^znxn. 



Caeco-colic fold. 



Fig. 45. — The caecum and its connections. 



The ileo-caecal and cseco-colic openings will be examined later with 

 the rest of the interior of the caecum. 



Four longitudinal muscular bands (tsenise cseci), ventral, dorsal 

 medial and lateral in position, produce four rows of sacculations 

 (haustra cseci) on the exterior corresponding to four rows of saccular 

 cells (cellulse cseci) in the interior of the tube. Three of the longi- 

 tudinal bands are associated with peritoneal folds : only one of them, the 

 ventral, being entirely free. 



The colon} — This part of the large intestine of the horse is 

 characterised by being readily divisible into two parts, namely — (1) an 

 enormous and capacious great colon that leads from the csecum and 

 resembles this in its calibre, and (2) a very much narrower small 



^ k6\ov (kolon) [Gr.], food, meat, fodder. The term was used by Aristotle in the 

 sense in which it is applied in anatomy to-day. 



