330 A MANUAL OF ANATOMY. 



to which it is attached. Above it is continuous with the 

 deep cervical fascia on the great vessels. 



Contents of the Pericardium. Heart (its auricles, ventri- 

 cles, arteries, veins, and nerves), ascending aorta, pulmo- 

 nary artery, pulmonary veins, superior vena cava. 



The Heart. Figs. 57, 58, 68 to 73. 



Is a hollow muscular cone, placed with its base upward, 

 backward, and to the right, and its apex downward, for- 

 ward, and to the left. For the surface relations consult 

 description already given. 



Its dimensions: Length, 5 inches; breadth, 3^ inches; 

 thickness, 2^ inches; weight, n ounces in the male, 9 in 

 the female. 



The heart is attached by its base to the great vessels 

 which proceed from it. Its apex is free and in life describes 

 considerable movement. 



It is divided into four cavities by two partitions, one 

 between the ventricles, the interventricular, one between 

 the auricles and ventricles, the auriculoventricular. 



The location of the partitions is indicated on the outside 

 of the heart by grooves, the auriculoventricular groove 

 being deeper and better marked than the interventricular. 

 The former is obliterated in front by the pulmonary artery. 

 The heart (and vessels for their first one and a half inch) is 

 covered by the visceral layer of the pericardium, and its 

 cavities are lined by a similar smooth membrane the endo- 

 cardium continuous with the lining of the blood vessels. 



On opening the pericardium the greater part of the heart 

 presenting is composed of the right ventricle and auricle ; 

 the smaller part, of the left ventricle and auricle. The 

 ascending aorta, pulmonary artery, and superior vena cava 

 are also in view. 



