368 



DIGESTIVE SYSTEM OF THE HORSE 



The relations are complex, Ijut the more important facts are as follows: The 

 ventral portions (first and second) have extensive contact with the abdominal wall 

 ventrally and laterally. On the right side the colon is almost entirely excluded from 

 contact with the flank ])y the caecum; on the left side it has no contact with the 

 upper part of the flank, being excluded here by coils of the small colon and small 

 intestine. Dorsally the chief relations are to the stomach, duodenum, liver, 

 pancreas, small colon, small intestine, aorta, vena cava, and portal vein. Since 

 there are no transverse attachments of the right and left portions, and the latter 

 have no attachment to the wall, they are subject to considerable displacement/ 





Fig. 271. — Topography of Visc'er.\ of Horsf., Left Deep View. 

 iiJ., First thoracic vertebra; iL., first lumbar vertebra; ;2 A'., second sacral spine; <S., scapula; ^..humerus; 

 iJ., ilium; 7^., femur; »Sc/t., pubis; «S'(., ischium; L., liver (left lobe); Ma., stomach, the posterior contour of which 

 is indicated by dotted line a-; Mi, spleen; I. N., left kidney, concealed part indicated by dotted line ; M., small 

 colon; D., small intestine, parts of which have been removed; I. d. C, left dorsal colon; l.v.C, left ventral colon; 

 V.Q., sternal flexure; d.Q., diaphragmatic flexure; O., left ovary; U., cornu uteri; L.I., broad ligament 

 M'., rectum; V., vagina; H., bladder; a, left ventricle; a', right ventricle; b, left coronary artery with descending 

 (6') and circumflex (6") branches; c, left auricle; d, pulmonary artery (cut); e, aorta; /, ligamentum arteriosum; 

 II, brachiocephalic trunk (anterior aorta); h, trachea; i, oesophagus; k, left phrenic nerve; /, diaphragm in median 

 section; m. Fallopian tube; n, bursa ovarica; o, urethra; p, cut edge of broad ligament; q, line of reflection of 

 pelvic peritoneum; r, recto-coccygeus; s, so-called suspensory ligament of rectum; t, sphincter ani internus; m, 

 sacro-coccygeus inferior; d, abdominal wall in section; w, xiphoid cartilage. (After EUenberger, in Leisering's 

 Atlas.) 



The pelvic flexure is variable in position, but usually it is directed to the right 

 across the pelvic inlet. 



The ventral portions of the colon have four longitudinal muscular bands 

 (Tffinise) which produce four rows of sacculations (Haustra). On the first part 

 the external and internal bands are free; the dorsal band is covered by the adhesion 

 to the overlying tlorsal division, while the ventral band is largely covered by the 

 adhesion to the caecum. On the left ventral part the external and ventral bands 

 are free; of the two dorsal bands, the inner one is concealed by the mesocolon, the 

 outer one is chiefly free. The pelvic flexure has a band on its lesser curvature, 

 which is continued on to the third part, concealed by the peritoneal attachment; 

 these parts are practically non-sacculated. Near the diaphragmatic flexure two 



' Abnormal displacement, e. g., torsion of the left parts, is not rare, and is liable to produce 

 death if not promptly reduced. 



