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ANGIOLOGY 



ing vessels, by which the blood is brought from the upper to the lower part of the artery, will be 

 found well described in an account of two cases in the Pathological Transactions, vols. viii and x. 

 In the former, Sydney Jones thus sums up the detailed description of the anastomosing vessels: 

 The principal communications by which the circulation was carried on were: (1) The internal 

 mammary, anastomosing with the intercostal arteries, with the inferior phrenic of the abdominal 

 aorta 'by means of the musculophrenic and pericardiacophrenic, and largely with the inferior 

 epigastric. (2) The costocervical trunk, anastomosing anteriorly by means of a large branch 

 with the first aortic intercostal, and posteriorly with the posterior branch of the same artery. 

 (3) The inferior thyroid, by means of a branch about the size of an ordinary radial, forming a 

 communication with the first aortic intercostal. (4) The transverse cervical, by means of very 

 large communications with the posterior branches of the intercostals. (5) The branches (of 

 the subclavian and axillary) going to the side of the chest were large, and anastomosed freely 

 with the lateral branches of the intercostals. In the second case Wood describes the anastomoses 

 in a somewhat similar manner, adding the remark that "the blood which was brought into the 

 aorta through the anastomosis of the intercostal arteries appeared to be expended principally 

 in supplying the abdomen and pelvis; while the supply to the lower extremities had passed through 

 the internal mammary and epigastrics." 



In a few cases an apparently double descending thoracic aorta has been found, the two vessels 

 lying side by side, and eventually fusing to form a single tube in the lower part of the thorax or 

 in the abdomen. One of them is the aorta, the other represents a dissecting aortic aneurism 

 which has become canalized; opening above and below into the true aorta, and at first sight 

 presenting the appearances of a proper bloodvessel. 



Branches of the Thoracic Aorta. 



Visceral 



Pericardial. 

 Bronchial. 

 Esophageal. 

 Mediastinal. 



( Intercostal. 

 Parietal < Subcostal. 



( Superior Phrenic. 



The pericardial branches (rami pericardiaci) consist of a few small vessels which 

 are distributed to the posterior surface of the pericardium. 



The bronchial arteries (aa. bronchioles) vary in number, size, and origin. There 

 is as a rule only one right bronchial artery, which arises from the first aortic inter- 

 costal, or from the upper left bronchial artery. The left bronchial arteries are usually 

 two in number, and arise from the thoracic aorta. The upper left bronchial arises 

 opposite the fifth thoracic vertebra, the lower just below the level of the left bron- 

 chus. Each vessel runs on the back part of its bronchus, dividing and subdividing 

 along the bronchial tubes, supplying them, the areolar tissue of the lungs, the 

 bronchial lymph glands, and the esophagus. 



The esophageal arteries (aa. cesophagece) four or five in number, arise from 

 the front of the aorta, and pass obliquely downward to the esophagus, forming 

 a chain of anastomoses along that tube, anastomosing with the esophageal branches 

 of the inferior thyroid arteries above, and with ascending branches from the left 

 inferior phrenic and left gastric arteries below. 



The mediastinal branches (rami mediastinales) are numerous small vessels which 

 supply the lymph glands and loose areolar tissue in the posterior mediastinum. 



Intercostal Arteries (aa. intercostales) . There are usually nine pairs of aortic 

 intercostal arteries. They arise from the back of the aorta, and a redistributed 

 to the lower nine intercostal spaces, the first two spaces being supplied by the highest 

 intercostal artery, a branch of the costocervical trunk of the subclavian. The 

 right aortic intercostals are longer than the left, on account of the position of the 

 aorta on the left side of the vertebral column; they pass across the bodies of the 

 vertebrae behind the esophagus, thoracic duct, and vena azygos, and are covered 

 by the right lung and pleura. The left aortic intercostals run backward on the 

 sides of the vertebrae and are covered by the left lung and pleura; the upper two 

 vessels are crossed by the highest left intercostal vein, the lower vessels by the 

 hemiazygos veins. The further course of the intercostal arteries is practically 

 the same on both sides. Opposite the heads of the ribs the sympathetic trunk 



Y) 



