THE DISEASES OF CATTLE. 215 



The heart is anatomically divided into four cavities, two of 

 which being in a superior and anterior direction ; and in 

 consequence of bearing some resemblance to the ears of a dog, 

 are termed auricles. These cavities known as right and left 

 (or rather anterior and posterior), are divided by a wall or 

 septum, known as the septum auriculorum. 



The right auricle is the receptacle for venous blood, and 

 three venous trunks terminate in it ; viz., the anterior vena 

 cava, which returns the venous blood from the anterior extrem- 

 ities, head and neck — next, the vena cava posterior, which 

 returns the venous blood from the posterior parts, and lastly 

 the coronary vein ; the latter returns blood which has circu- 

 lated through the heart itself for its own nourishment. A con- 

 siderable quantity of dark venous blood is generally found in 

 this auricle after death, and it opens into the right, or anterior 

 ventricle, by an aperture denominated the auriculo-ventricular 

 opening, yet in consequence of a valvular contrivance within 

 the ventricle, the blood cannot recede into the auricle. 

 . Internally, the right auricle is lined by a glistening vascular 

 membrane having on various parts of its surface small mus- 

 cular eminences, termed musculi pectinati ; the small cavities 

 which occur, in consequence of this arrangement, are termed 

 cul-de-sacs. The right, or venous ventricle, is also lined by a 

 nicely organized membrane and has beneath it several muscular 

 prominences named camcB columnce. which give origin to as 

 many tendinous slips, these are known as cordm tendince, they 

 are inserted into a fibrous membrane in the region of the 

 auriculo-ventricular opening, and then get the name (membrane 

 included) valvula tricuspis. The lateral contractions of this 

 ventricle are aided by small tendinous cords having muscular 

 origins from the wall and septum. The venous blood passes 

 from this cavity into the pulmonary tissues of oxygenation, 

 through the pulmonary artery, which emerges from the 

 superior part of the ventricle. At the commencement of the 

 pulmonary artery are found three valves termed semilunar, 

 their function is to guard against a retrogade movement of the 



