The Axilla. 43 



tendon of the deltoid muscle to the point where the upper 

 border of pectoralis minor crosses the axillary artery. 

 The subscapulat arteiy arises from the line of the axillary 

 artery and passes down along the edge of the subscap- 

 ularis muscle, i.e. about one inch above the lower border 

 of the posterior fold of the axilla. The point of origin of 

 the dorsalis scapulae is about one inch from the beginning 

 of the subscapular aitery. The line for the circumflex 

 arteries corresponds to a line starting from the line of the 

 axillary artery and passing around the surgical neck of the 

 bone, i. e. about half an inch above the middle of the 

 vertical axis of the deltoid muscle. 



The landmark for the posterior thoracic netve corre- 

 sponds fairly well to a line drawn from the outer border 

 of the sterno-mastoid muscle about on a level with the 

 cricoid cartilage, crossing the clavicle a little to the inner 

 side of its middle, and being continued downwards to the 

 lower part of the mid-axillary line. 



Operative work on the Axilla. In operating 

 on the axillary region it is well to bear in mind that the 

 greatest depth of the axilla is when the arm is at an angle 

 of 45 ,and that, in examining the head of the humerus it 

 is best felt with the arm close to the side so as to relax the 

 axillary fascia proper. When the arm is abducted the ax- 

 illa is rendered shallower, and the greater the amount of 

 abduction, the greater the danger of the vein being wound- 

 ed, since, in abduction, this vessel lies in front of the artery. 

 In opening an abscess in the main cavity of the axilla or 

 in the removal of diseased glands, the incision should be 

 made midway between the anterior and posterior folds, 

 i.e., between the pectoralis major in front and the latiss. 

 dorsi behind, and it should be nearer to the thoracic than 

 to the humeral side of the base and, as a rule, the 

 best method of opening an axillary abscess is 



