530 



THE BLOOD-VASCULAR SYSTEM 



the sternum to the upper border of the right second chondrosternal articulation. 

 It measures about 5 to 5.5 cm. (2 to 2j in.), forming, as it ascends, a gentle curve 

 with its convexity to the right. It is enclosed for the greater part of its length in 

 the pericardium, being invested, together with the pulmonary artery, in a com- 

 mon sheath formed bj^ the serous layer of that membrane. A dilatation known 

 as the bulbus aortae occurs immediately above the heart upon which are three 

 localized bulgings, known as the aortic sinuses (sinuses of Valsalva); they are 

 placed, one to the right, one to the left, and one posteriorly. From the right and 

 eft are derived the coronary arteries of the heart. (See Heart.) 



) 



Fig. 441. — The Great 



(Modified from a dissection in St 



Internal jugular vein 



Transverse cervical 



artery 

 Transverse scapular 



artery 



Right inferior laryn- 

 geal nerve 



Right common carotid 

 artery 



Subclavian vein 



Vagus nerve -"S^ 



Innominate artery "^TZ^ 



Left innominate vein 



Phrenic nerve 



Superior vena cava 



Arch of aorta 



Right bronchus 



Branch of right pul- 

 monary artery 



Branch of right pul- 

 monary vein 



Right pulmonary 

 artery 

 Branch of right pul- 

 monary artery 



Branch of right pul- 

 monary vein 



Right atrium 



Right coronary artery 

 Thoracic vertebra 



Azygos vein 



Intercostal veins 



Intercostal arteries 



Vessels of the Thorax. 

 Bartholomew's Hospital Museum.) 



Inferior thyreoid veins 



'Thyreoid gland 



Left internal jugular 



vein 

 .Vagus nerve 



Left common carotid 



artery 

 Left inferior laryngeal 

 nerve 



-Left subclavian artery 



Left subclavian vein 

 Left internal mammary 



vein 

 Left superior inter- 

 costal vein 



Phrenic nerve 

 Vagus nerve 



Recurrent nerve 



Ligamentum arteri- 

 osum 



Left pulmonary artery 

 Left pulmonary vein 



Left bronchus 



Branch of left pulmon- 

 ary artery 



Pulmonary artery 

 Left pulmonary vein 



Left coronary artery 



Conus arteriosus 



CEsophagus 

 —Thoracic duct 

 Thoracic aorta 



Relations. — In front, it is overlapped at its commencement by the right auricle, conut 

 arteriosus and pulmonary artery. Ilifrher up, as the pulmonary artery and auricle diverge, is 

 is separated from the manubrium by the pericardium, the remains of the thymus gland, and by 

 the loose tissue and fat in the superior mediastinum, and is hei'e slightly overlapped by the right 

 pleura and by the edge of the right lung in full inspiration. The root of the right coronary 

 arterj' is also in front. 



Behind are the left atrium of the heart, the right pulmonary artery, the right bronchus, 

 and the anterior right deep cardiac nerves. 



On the right side it is in contact, below with the right atrium, and above with the superior 

 vena cava. 



On the left side are the pulmonary artery and the branches of the right superficial cardiac 

 nerves. 



Branches. — The right and left coronary arteries have already been described (p. 519). 



The Arch of the Aorta 



The arch of the aorta [arcus aortte] (figs. 441, 442), extends in a gentle curve 

 upward, backward, and to tlic left, from the level of the upj)er border of the 



I 



