DISEASES OF THE HEART AND BLOODVESSELS. 



By M. R. TRUMBOWER, V. S., Sterling, III. 



REMARKS ON THE ANATOMY AND PHYSIOLOGY OF THE HEART AND 



BLOOD VESSELS. 



The heart is a hollow, involuntary, muscular organ, situated as nearly 

 as possible in the center of the chest, though its impulse is felt on the 

 left side from the rotary movement of the organ in action. It is cone- 

 shaped, with the base upwards; the apex points downwards, backwards, 

 and to the left side. It extends from about the third to the sixth ribs 

 inclusive. The average weight is about 6 J pounds. In horses used for 

 speed the heart is relatively larger, according to the weight of the ani- 

 mal, than in horses used for slow work. It is suspended from the spine 

 by the large blood-vessels, and held in position below by the attach- 

 ment of the pericardium to the sternum. It is inclosed in a sac, the 

 pericardium, which is composed of a dense, fibrous, membrane, lined by 

 a delicate serous membrane, which is reflected over the heart; the inner 

 layer is firmly adherent to the heart, the outer to the fibrous sac, and 

 there is an intervening space known as the pericardial space, in which 

 a small amount of serum — a thiu translucent liquid — is present con- 

 stantly. 



The heart is divided by a shallow fissure into a right and left side ; 

 each of these is again subdivided by a transverse partition into two 

 compartments, which communicate. Thus there are four cardiac cavi- 

 ties, the superior or upper ones called the auricles, the inferior or 

 lower ones the ventricles. These divisions are marked on the outside 

 by grooves, which contain the cardiac blood-vessels, and are generally 

 filled with fat. 



The right side of the heart may be called the venous, the left the ar- 

 terial side, named from the kind of blood which passes through them. 

 The auricles are thin- walled cavities placed at the base, and are con- 

 nected with the great veins, the vena cavse and pulmonary veins, through 

 which they receive blood from all parts of the body. The auricles com- 

 municate with the ventricles each by a large aperture, the auriculo- 

 ventricular orifice, which is furnished with a remarkable mechanism of 



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