392 DIGESTIVE SYSTEM OF THE OX 



with the reticulum, a ventral groove (Sulcus rumino-reticularis) being the only 

 external line of demarcation. Dorsally no natural separation exists, the rumen 

 and reticulum together forming a dome-like vestibule (Atrium ventriculi) on which 

 the esophagus terminates. The pelvic (or posterior) extremity (Extremitas 

 pelvina) extends nearly to the pubis, and is related to the intestine and bladder, 

 and the uterus in the cow. It is divided into dorsal and ventral blind sacs (Saccus 

 csecus caudalis dorsalis, ventralis) by a deep transverse groove (Sulcus ruminis 

 caudalis) in which the longitudinal furrows terminate. The blind sacs are marked 

 off from the remainder of the rumen by the dorsal and ventral coronary grooves 

 (Sulcus coronarius dorsalis, ventralis). 



The left longitudinal groove (Sulcus longitudinalis sinister) begins at the anterior transverse 

 groove, passes somewhat dorsally and backward and di^•ides into two grooves. The ventral 

 one is the chief groove and passes backward to terminate in the angle of union of the posterior 

 blind sacs. The dorsal (accessory) groove curves dorsally and then backward to terminate in 

 the dorsal coronary sulcus. On the right surface there are two longitudinal grooves. The dorsal one 

 is the chief sulcus (Sulcus longitudinalis dexter). It extends in a curved direction (the convexity 

 being dorsal) and is continuous with the left longitudinal groove by means of the grooves between 

 the dorsal and ventral blind sacs at each end. The ventral groove (Sulcus accessorius) curves 

 somewhat ventrally and backward to rejoin the chief sulcus between the posterior blind sacs. 



The reticulum is the smallest of the four divisions in the ox. It is also the 

 most anterior, and lies on the concave surface of the diaphragm, so that the median 

 plane divides it into two nearly equal portions. It is somewhat pyriform, 

 but much compressed from before backward. The parietal or phrenic surface 

 (Facies diaphragmatica) is convex and lies against the diaphragm and liver.' 

 The niminal (or posterior) surface (Facies ruminalis) is flattened by the ])ressure 

 of the other three compartments; it ends dorsally by joining the wall of the rumen, 

 the concave line of junction forming, in the interior of the stomach, the lower margin 

 of the large rumino-reticular orifice. The omasal (or right) surface is narrow and 

 concave, and is connected with the omasum. The dorsal curvature by its left 

 portion joins the riunen to form the atrium, and by its right jjortion touches the 

 liver. The ventral curvature lies on the sternal portion of the diaphragm , opposite 

 the sixth and seventh ribs. The right extremity forms a rounded cul-de-sac, 

 which is in contact with the liver, omasum, and aliomasum. 



The omasum (Fig. 294) is ellipsoidal in form and somewhat compressed laterally. 

 It is very clearly marked off from the other divisions. It is situated almost entirely 

 to the right of the median plane, opposite the seventh to the eleventh ribs. The 

 parietal (right) surface (Facies dextra) lies against the diaphragm, liver, and lateral 

 wall of the abdomen. The contact with the latter extends over a small area only 

 (ventral ]iart of seventh to ninth intercostal spaces). The visceral (left) surface 

 (Facies sinistra) is in contact with the rumen and reticulum. The dorsal (greater) 

 curvature is convex, and is related to the diaphragm, liver, and vena cava. The 

 ventral (lesser) curvature is concave, and rests on the abomasum chiefly, the junc- 

 tion with the latter appearing as a constriction near the middle of the curvature; 

 at its anterior part tliere is a neck (Collum omasi) whicli is the connection with the 

 reticulum. 



The abomasum (Fig. 294) is an elongated j^yriform or flask-shaped sac, which 

 lies for the most part on the abdominal floor, to the right of the ventral sac of the 

 rumen. Its luirrow posterior part is strongly curved, the concavity being dorsal. 

 Tlic parietal (right) surface lies against the al)dominal wall from the seventh to the 

 twelfth intercostal space. The visceral ( left ) surface is related chiefly to the ventral 

 sac of the rumen. The dorsal (lesser) curvature is concave, and is in contact with the 

 omasum; the junction of the two sacs is indicated by a constriction about four or 



' It is important to notice that the reticulum is separated from the pericardium by an 

 interval of about 1 to 1 J/2 inches (ca. 2 to 4 cm.) only, since foreign bodies which are often swal- 

 lowed by cattle lodge in the reticulum, and not rarely (if sharp) perforate the reticulum and 

 diaphragm. 



