354 A MANUAL OF ANATOMY. 



The Cardiac Nerves. 



The cardiac nerves are supplied from the pneumogastric, 

 recurrent laryngeal nerves, and the three cervical ganglia. 



The minute filaments from these sources interlace in the 

 concavity of the aortic arch, in front of the right pulmonary 

 artery (forming the superficial cardiac plexus), and be- 

 hind the transverse aorta, between the trachea and the 

 transverse aorta (forming the deep cardiac plexus). 



The deep plexus receives branches from all the sources 

 above, except from the left superior sympathetic cardiac 

 and the left inferior cardiac of the pneumogastric. The 

 superficial plexus is formed by the two exceptions above 

 and by the branches from the deep plexus itself. 



From these plexuses branches descend to the heart and 

 lungs. 



Inferior Vena Cava. 



For formation and course see Abdomen. 



It enters the thorax from the abdomen through the caval 

 opening in the diaphragm to the right of the thoracic aorta, 

 and in front of the dorsal vertebrae, and empties into the 

 right auricle of the heart. It is covered by pericardium for 

 about one-half inch. 



The Heart. (See page 330.) Figs. 70 to 73. 



Note its shape, size, position of parts, and their relations 

 to each other. For the external relations see page 258. 



Open the ventricles by incisions from the pulmonary 

 artery and the aorta to the apex through the right and left 

 sides of the heart. Open the auricles by incisions parallel 

 with the auriculoventricular groove. 



The Right Auricle. Openings, superior vena cava, in- 

 ferior vena cava, auriculoventricular, coronary sinus, fora- 

 mina Thebesii. 



