270 SUBCLAVIAN AXILLARY. 



the Inferior Thyroid and the other from one of the branches of 

 the Subclavian.* 



The Superior Scapular most commonly arises with some 

 other artery, and very often from the Inferior Thyroid. It runs 

 transversely outwards within and above the clavicle, and passing 

 through the notch in the upper costa of the scapula, divides 

 into branches which are distributed to the _parts on the dorsum 

 of that bone. 



The Subdqvian Artery, in its progress from the aorta to the 

 axilla, forms an arch or curve, over the fifth rib, as has been 

 already observed. The anterior scalenus muscle is before it, 

 and the great nerves of the upper extremity are above it. After 

 passing between the scaleni, it descends upon the first and 

 second rib into the axilla. The nerves which are above descend 

 with it ; at first they are necessarily exterior to it ; but they 

 form a plexus which the artery enters into, so as to be partly 

 surrounded by them. This course of the artery is obliquely 

 under the clavicle, and behind the pectoral muscle. In the 

 axilla, the vessel and nerves which surround it are placed be- 

 tween the tendons of the pectoralis and the latissimus dorsi 

 muscles. Here the artery takes the name of Axillary, and 

 sends off several important branches. 



The principal branches that ge off from the axillary artery 

 are distributed, 



1st. Anteriorly, to the pectoral muscle, and the parts on the 

 anterior surface of the thorax. 



2d. Posteriorly to the muscles which are on the scapula and 

 contiguous to it ; and 



3d. To the parts which are near the upper extremity of the 

 os humeri. 



* Haller paid great attention to the arterial system, and made man)' dissec- 

 tions, with a view to engravings of it, which he published with descriptions in 

 jfolio fasciculi. 



These fasciculi have been collected, and, with some other engravings, form a 

 large volume, entitled ICONES ANATOMICJE, which is truly valuable. 



There are some very interesting observations on this work of Haller's, and 

 also on these arteries, in a DESCRIPTION OF THE ARTERIES, by Dr. Barclay, of 

 Edinburgh, which I have read with advantage, as well as a work on the mus- 

 cles by the same author. 



I 



