336 



PRACTICAL ANATOMY. 



which it is closely adherent The serous lining of the 

 pericardium consists of two layers, the visceral and 

 parietal. The visceral layer closely invests the heart and 

 roots of the great vessels, and is reflected on the inner 

 surface of the fibrous layer of the pericardium. Both 

 parietal and visceral surfaces are smooth and glistening. 

 A small amount of fluid is found within the sac. 



The heart is contained within the pericardial sac. It 

 is a hollow, muscular organ, conical in form, and situated 



in the middle mediasti- 

 num between the two 

 lungs. It is placed 

 obliquely, the base is 

 above, the apex below, 

 and it extends from the 



right third costo-sternal 

 articulation to the fifth 

 intercostal space on the 

 left side, about one and 

 one-half inches to the 

 left of the sternum. It 

 is held in position by 

 the great vessels which 

 spring from its base, and 

 is entirely free to move throughout the rest of its extent. 

 It is about five inches long, three inches transversely, 

 and two and one-half inches antero-posteriorly ; roughly 

 speaking, it is about the size of the fist. . It weighs 

 from eight to ten ounces in the female and from nine 

 to eleven ounces in the male. It consists of two ven- 

 tricles and two auricles ; the auricles, right and left, 

 are two cuboidal sinuses, which receive the blood ; below 

 these are placed the ventricles, which force the blood 

 into the pulmonary artery and aorta, A vertical sep- 



FIQ. 144. RIGHT SIDE OF HEAKT, RIGHT 

 AURICLE AND RIGHT VENTRICLE LAID 

 OPEN. 



a, apex ; b, right ventricle ; d, pulmonary artery ; 

 e, f, chordae tendinse ; p, aorta; 3, superior vena cavu: 

 5, inferior vena cava. 



