770 



HUMAN ANATOMY. 



The symptoms are («) sivcUing showing immediately below the clavicle (in 

 Mohrenheim's fossa) and pushing that bone upward if the first portion is involved, 

 or pushing the pectoral muscles forward if the aneurism is lower, or appearing as a 

 pulsating tumor in the axilla if the thu'd portion is involved ; {b)ccde7na of the arm 

 and hand from pressure on the axillary vein ; {c) pain down the arm, in the shoulder 

 and neck, and down the side of the chest, and feebleness and limitation of shoulder 

 and arm movements from, first, spasm, then paresis of the associated muscles, all due 

 to pressure on the brachial plexus and its branches. 



Digital compression of the axillary artery is only effectively possible in the lower 

 part of the third portion, where, with the fingers beneath the anterior axillary fold, 



Fig, 706. 



Cut fibres 

 of pectoralis 



major Clavicle Subclavius Axillary artery 



Brachial plexus 



Pectoralis minor 



Pectoralis 



major, 

 turned back 



First intercostal space 



Subclavian vein Pectoralis 

 major, cut 



Second rib 



Dissection showing relations of axillary artery in first part of its course. 



the vessel, if the effort is made with due care and gentleness, may be flattened against 

 the humerus just within the edge of the coraco-brachialis and biceps. 



Ligation of the Jirst portion may be effected in two ways : i. With the arm 

 abducted to a right angle, an incision three inches long, slightly convex downward, 

 and with its centre about an inch below the middle of the clavicle, is made through 

 the skin, superficial fascia, and platysma. The cephalic vein, and the descending 

 branch of the acromial thoracic artery will be seen, just beneath the fascia, in the 

 groove between the deltoid and greater pectoral muscles. The outer clavicular fibres 

 of the pectorahs major are then divided close to the clavicle ; the interpectoral and 

 axillary fascia and some loose connective tissue are broken up ; the upper border of 

 the pectoralis minor is identified and traced to the coracoid process ; the costo-cora- 

 coid membrane is cautiously cut through by a vertical incision close to the coracoid ; 

 the artery is then sought for, lying between the brachial plexus of nerves externally and 



