SECTION lY 



ARTERIES, VEINS, AND LYMPHATICS 



By W. J. WALSH AM, F.KC.S. 



SURGEON TO ST. BARTHOLOMEW'S HOSPITAL; LECTURER ON SURGERY; LATE LECTURER ON ADVANCED ANATOMY IN 

 ST. BARTHOLOMEW'S HOSPITAL MEDICAL SCHOOL, ETC., ETC. 



THE ARTERIES 



THE arteries are divided into the pulmonary and the systemic. The pul- 

 monary convey the blood from the right ventricle of the heart to the lungs, 

 whence it is returned, when aerated, by the pulmonary veins to the left 

 auricle, and through that cavity into the left ventricle. The systemic arteries 

 carry the blood from the left ventricle all over the body, whence it is returned by 

 the vense cavse to the right auricle, and through it to the right ventricle. The lungs 

 also receive blood from the systemic arteries — the lironchial. This Idood which 

 serves for the nourishment of the larger and smaller branches of the bronchial 

 tubes and the lung substance is returned, in part by the bronchial veins to the 

 general venous circulation, and thence to the right side of the heart; and in part by 

 the pulmonary veins, along with the aerated blood, to the left side of the heart. 



THE PUMIONARY ARTERY 



The pulmonary artery (fig. 317) passes from the right ventricle to the lungs. 

 It differs from all other arteries in the body in that it contains venous blood. It 

 arises as a short, thick trunk from the upper and front part of the right ventricle 

 kn^wn as the conus arteriosus, and, after a course of about two inches within the 

 pericardium — the serous layer of which memlirane forms a common sheath for it 

 and the aorta — divides into a right and a left liranch. These branches pierce the 

 pericardium, and pass to the riglit and loft lung respectively. 



The trunk of the pulmonary artery at its origin (fig. 319) is on a plane 

 anterior to the first j^ortion of the an;h of the aorta, and slightly overlaps that 

 vessel. Tlionce it passes upwards, backwards, and to the left, forming a sliglit 

 curve round the front and left side of the ascending portion of the aorta (fig. 321); 

 and, having reached tlie concavity of the transverse j)()rtion of the aortic arch, on a 

 level with the fifth thoracic vertebra, and on a ])lane ]>osterior to the ascending 

 aorta, it divides into its right and left branches, which diverge from each other at 

 an angle of about 130°. 



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