CHAPTER VIII 



THE DESCRIPTION OF THE ANATOMY AND 



PHYSIOLOGY OF THE CIRCULATORY 



APPARATUS 



THE circulatory apparatus consists of the heart, 

 covered by the pericardium, the arteries, veins, and 

 capillaries, and circulating fluid the blood. 



THE PERICARDIUM 



The pericardium is a serofibrous membrane which 

 invests the heart and the great vessels at their origin 

 for about two inches. The pericardium consists of a 

 fibrous and serous layer, between which is a small 

 amount of serous fluid, preventing friction, as at 

 each rhythmic contraction of the heart these layers 

 rub against each other. The serous layer (epicar- 

 dium) invests the heart muscle and is reflected to 

 the fibrous layer. 



THE HEART 



The heart is a hollow muscular organ situated in 

 the thorax between the right and left lobes of the 

 lungs, enclosed by the pericardial sac. 



It lies obliquely, the base being directed upward, 

 backward, and toward the right, its position corre- 

 sponding to the surface of the chest wall extends 

 from the fifth to the eighth thoracic vertebra. The 

 apex looks downward, forward, and to the left, its 



