ANATOMY IN A NUTSHELL. 



239 



to the heart. The tenth and sympathetic go to the lungs substance, while the 

 phrenic and sympatheic pass to the pleura. 



LESSON LXV. 



The heart (Plate CXXVIII.) is situated in the middle mediastinum be- 

 tween the spinous processes of the fourth dorsal and eighth dorsal vertebra 

 posteriorly. Its apex is directed downward and forward to the left, and lies 

 against the fifth intercostal space three -quarters of an inch to the inn< r sid of 



PLATE XCVI. 



ROUGH SURFACE 

 FOR 

 CHECK LJGAMEW. 



SUP. ARTIC. 

 PROC. 



ODONTOID 

 PROC. 



ARTIC. GROOVE FOR 

 TRANSVERSE LIG. 



LAMI 



SPINOUS PROC 



Posterior View of Axis. 



the left nipple and an inch and a half below the same. The heart lies obliquely 

 behind the lower tw< -thirds of the sternum, extending about three inches to 

 the left of the median line and one and a half inches to the right. Its anterior 

 surface consists mostly of the light ventricle and a part of the left ventricle. 

 It is convex and looks upward and forward. Its posterior surface consists 

 mostly of the left ventricle and rests upon the Diaphragm. This surface is 

 flattened. The right border of the heart is long and thin, while the left is short 

 and thick. 



The average weight of the heart is about eleven ounces. In the male it 

 weighs from ten to twelve ounces, while in the female its weight is from eight 

 to ten. The adult heart is five inches long by three and a half wide, by two 

 and a half thick. It is divided into four chambers, namely, the right and left 

 auricles and the right and left ventricles. The right side of the heart, which is 

 more superficial and is called the venous heart, is separated from the left side 

 of the heart, which is deeper and is called the arterial heart, by a longitudinal 

 septum, and each of these lateral halves are divi led bya transverse septum,thus 

 making the auricles and ventricles. 



These four divisions of the heart are indicated by grooves on its surface. 

 The apex of the heart is formed entirely by the left ventricle. These grooves 

 on the surface of the heart contain the coronary arteries, cardiac veins, lymphat- 

 ics, nerves and fat. 



