DIGESTIVE SYSTEM OF THE PIG 



obliquely and projects considerably into the latter. A fold of mucous membrane 

 (Frenulum ilei) passes from each side of the ileo-csecal opening. The colon has at 

 first about the same caliber as the ctecum, but becomes gradually smaller. It lies 

 chiefly to the left of the median plane, behind the stomach. Most of it is arranged 

 in three close, double spiral coils in the mesentery, in relation with the floor of the 

 abdomen ventrally, the stomach and liver in front, the caecum and small intestine 

 behind, and the small intestine on the right. On emerging from this spiral laby- 

 rinth it passes at first forward in the sublumbar region to the right of the median 

 plane, and, on reaching the stomach and right end of the pancreas, turns to the left. 

 It then passes backward, on the ventral surface of the pancreas, and in relation to 

 the medial part of the left kidney, inclines medially, and is continued at the pelvic 

 inlet by the rectum. This terminal part is closely attached by a short mesentery to 

 the sublumbar region. The rectum is usually surrounded by a quantity of fat. 

 The caecum has three longitudinal muscular bands and three rows of sacculations, 

 which are continued a short distance on the colon. The spiral colon has two bands 

 and two series of sacculations, which, however, gradually disappear in the centrif- 

 ugal part. The solitary nodules are numerous, and appear as round prominences, 

 2-3 mm. in diameter, often with a crater-like depression. The last Peyer's patch 

 of the small intestine is continued a variable distance in the caecum, and there are 

 often patches in the first part of the colon. 



THE LIVER 



The liver is relatively large, its average weight in the adult being about four 

 pounds (ca. 1.5-2 kg.). It is thick centrally, but the circumference is thin. It is 

 divided by three deep interlobar incisures into four principal lobes — right lateral, 

 right central, left central, left lateral; the last of these is usually considerably the 

 largest. On the upper part of the right lateral lobe, is the caudate lobe, which is 

 clearly marked off by a fissure and is often partially subdivided by a secondary 

 fissure. That part of the right central lobe which lies below the portal fissure and 

 to the left of the gall-bladder and cystic duct is homologous with the quadrate lobe 

 of man. Much the greater part is to the right of the median plane. The parietal 

 surface is extremely convex in conformity with the curvature of the diaphragm, to 

 which it is chiefly related. ■'^ A small part of the surface is in contact with the 

 abdominal floor in the xiphoid region and ventral to the right costal arch. Its 

 most anterior part reaches to a transverse plane through the ventral part of the 

 sixth rib or intercostal space. The visceral surface is deeply concave; most of it 

 is related to the stomach, for which there is a correspondingly large and deep gastric 

 impression. There may be a duodenal impression on the upper part of the right 

 lateral lobe, but no renal impression exists, as the right kidney does not touch the 

 liver. The fossa for the gall-bladder (Fossa vesicae felleae) is mainly on the right 

 central lobe, but also in part on the adj acent surface of the left central lobe. The pos- 

 terior vena cava enters the dorsal border of the caudate lobe and soon becomes entirely 

 embedded in the gland substance, emerging only at its passage through the dia- 

 phragm. The (esophageal notch is large and is occupied mainly by the large right 

 crus of the diaphragm. The right lateral border extends backward to the upper 

 part of the last intercostal space. The left lateral border is opposite the ninth 

 intercostal space and eighth rib. The ventral border lies on the abdominal floor 

 a short distance (ca. 3-5 cm.) behind the xiphoid cartilage. 



The coronary ligament resembles that of the horse. The falciform ligament is 

 very short or absent in the adult, and is attached to the diaphragm just below the 



1 The description here given is based on the appearance of the organ as hardened in situ, 

 which differs radically from that of the soft organ. It also differs much in shape in young and 

 adult subjects. 



