458 



DIGESTIVE SYSTEM OF THE OX 



ventral and lateral margin of the large, oval rumino-reticular orifice (Ostium 

 rumino-reticulare). The medial margin of the fold, if continued, would end about 

 at the cardia, but there is in this region no demarcation between rumen and reticu- 

 lum; hence it is termed the atrium ventriculi. 



The lateral border of the rumino-reticular fold ends above the level of and behind the plane 

 of the cardia, the medial one just behind the oesophageal groove and about four to five inches 

 lower down. Undoubtedly food or water swallowed with even a small degree of force passes first 

 into the rumen. Foreign bodies (which are commonly swallowed by cattle) are, however, found 

 in the reticulum. 



The cardia is opposite the seventh intercostal space or eighth rib, a little to the 

 left of the median plane, and about a handbreadth (ca. 10-12 cm.) ventral to the 

 vertebral column; it is not funnel-shaped. 



The mucous membrane of the rumen is brown in color, except on the margins 





■J ^* 



Fig. 390. — Reticulum of Ox, from Photograph. 

 The specimen was cut along the greater curvature and laid open by reflecting the anterior wall. C is the cardia. 

 The arrow points to the reticuJo-omasal orifice. The spiral twist of the oesophageal groove was of necessity partly 

 undone by reflecting the wall ; its lips are drawn apart, showing some of the peculiar birdclaw-like papillte in the 

 ventral part. 



of the pillars, where it is pale. It is for the most part thickly studded with large 

 papillae, many of which are nearly half an inch (ca. 1 cm.) long. The edges of the 

 chief pillars and a large part of the wall of the middle of the dorsal sac are, however, 

 not papillated. The papillary arrangement is most developed in the blind sacs. 

 The papillae vary much in size and form; the largest are foliate, many are narrow 

 or filiform, and others are conical or club-shaped. The mucous membrane on the 

 medial wall of the atrium is finely wrinkled and non-papillated, while dorsally and 

 laterally it is papillated. The papillary arrangement also extends over the edge 

 of the rumino-reticular fold an inch or two (ca. 2 to 5 cm.). 



The oesophageal groove (Sulcus oesophagus) begins at the cardia and passes 



