422 



DIGESTIVE SYSTEM OF THE HORSE 



Lymphoid tissue occurs in the form of distinct nodules (Noduli Ijonphatici), 

 which are either scattered or in groups. In the former case they are termed solitary 

 nodules (Xoduli lymphatici solitarii), in the latter aggregated nodules or Payer's 

 patches (Noduli lymphatici aggregati) . The solitary nodules are about the size of 

 a millet-seed or a small sago grain. The patches are situated chiefly along the 

 surface opposite to the mesenteric attachment and begin about three or four feet 

 from the pylorus. They number one to two hundred, and are usually one to two 

 inches (2 to 5 cm.) long and a quarter of an inch to one-half inch (ca. 2 to 14 mm.) 

 wide. Larger ones occur in the terminal part, where one patch may have a length 

 of seven to fifteen inches (ca. 17 to 38 cm.) and a width of half an inch to one inch 

 (ca. 5 to 25 mm.) in young horses (EUenberger). They vary much in number, 

 size, and distribution in different individuals, and undergo atrophy in old subjects. 



Vessels and Nerves. — The arteries of the small intestine come from the 

 coeliac and anterior mesenteric arteries. The veins go to the portal vein. The 

 lymph-vessels are numerous and go to the mesenteric lymph glands, thence to the 







:\ 



Fig. 361. — Large and Small Aggregated Nodulbs or Peter's Patches of Small Intestine of Horse. 



cisterna chyh. The nerves are derived from the vagus and sympathetic through 

 the coeliac plexus. 



THE LARGE INTESTINE 



The large intestine (Intestinum crassum) extends from the termination of the 

 ileum to the anus. It is about twenty-five feet (ca. 7.5 to 8 m.) in length. It 

 differs from the small intestine in its greater size, in being sacculated for the most 

 part, possessing longitudinal bands, and having a more fixed position. It is divided 

 into cfficum, great colon, small colon, and rectum. 



The CECxrai 



The cgecum (Intestinum cgecum) is a great cul-de-sac intercalated between the 



small intestine and the colon. It has a remarkable size, shape, and position in the 



horse. Its average length is about four feet (ca. 1.25 m.), and its capacity about 



seven to eight gallons (ca. 25 to 30 liters). ^ It is conical in form, and is curved 



' The length given here is measured from end to end along the side and midway between the 

 curvatures. 



