ARTERIES 8 1 



Course and Relations. Lies in posterior mediastinum ; is at 

 first to left of bodies of vertebrae, but afterwards lies in 

 front of them. 



In front. Root of left lung, pericardium and diaphragm, 

 crossed by oesophagus at lower end. 



Behind. Bodies of vertebrae and venae azygoi minores, 

 superior and inferior. 



Left side. Left lung and pleura, oesophagus below. 



Right side. (Esophagus above, thoracic duct, and vena 

 azygos major : right lung and pleura. 



Branches : 



Bronchial : supply structure of lungs. For the left lung two 

 branches come off from front of aorta (superior and inferior). 

 The artery supplying right lung arises either with or from 

 superior left branch, or from first right aortic intercostal. 



Pericardial : small twigs to posterior surface of pericar- 

 dium. 



(Esophageal (4 or 5) : from front of aorta, running obliquely 

 downwards to supply oesophagus ; anas, with one another, 

 inferior thyroid and coronary of stomach. 



Posterior mediastinal : supply glands, etc., of posterior 

 mediastinum. 



Intercostal (9 pairs) : arise from posterior part of aorta, 

 run transversely outwards on bodies of vertebrae, and behind 

 pleura to intercostal spaces. The right ones, crossing over 

 front of spine, supply the bodies of vertebrae, and pass behind 

 oesophagus, thoracic duct, and azygos veins. The arteries of 

 both sides are crossed by sympathetic chain and its splanch- 

 nic branches. On reaching intercostal spaces, they divide 

 into anterior and posterior branches ; the anterior branch 

 crosses the space obliquely upwards so as to get to lower 

 border of the upper rib near the angle : at first it lies between 

 external intercostal and fascia, subsequently between two 

 intercostal muscles ; anas, anterior intercostal of internal 

 mammary, thoracic branches of axillary. Above the artery 

 is a companion vein, and below the intercostal nerve. A 

 branch, the collateral intercostal, is given off near the angle of 

 the rib, which runs along the upper border of the lower rib ; 

 anas, anterior intercostal. Branches accompany the lateral 

 cutaneous nerves of the thorax from the main trunks of the 

 intercostals. The three lower branches pass forwards between 

 muscles of abdominal wall ; anas, epigastric and lumbar. 



The posterior branch passes backwards between vertebra 

 and superior costo- transverse ligament, sending inwards, spinal 

 branch through intervertebral foramen to cord, membranes 



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