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Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.
 
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.
Parietal    Intercostal.
Bronchial.
Subcostal.
Esophageal.
Superior Phrenic.
Mediastinal.


  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. bronchiales) vary in number, size, and origin. There is as a rule only one right bronchial artery, which arises from the first aortic intercostal, 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 bronchus. 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. æsophageæ) 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 vertebræ 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 vertebræ 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

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