The Axilla. 41 



subscapular nerves, the teres major by the lower sub- 

 scapular nerve, the latiss. dorsi by the long subscapular 

 nerve, the teres minor by the circumflex, the subclavius 

 by a branch from the fifth cervical, and the ser- 

 ratus magnus by the posterior thoracic or external respi- 

 ratory from the 5th, 6th and ytb, while the integument 

 of this region is supplied by the lateral cutaneous 

 branches of the intercostals, the intercosto-humeral and 

 the supraclavicular and supra-acromial nerves. 



The brachial plexus lies on the outer side of the first 

 part of the axillary artery. It is here narrow but it soon 

 divides and the union of the different branches forms the 

 outer cord which lies on the outer side of the second part 

 of the axillary artery and the inner and posterior cords 

 which appear on the inner and posterior parts of the 

 vessel respectively. Lastly, these cords divide and 

 form the nerves of the upper limb which are situated 

 with reference to the third part of the artery as follows : 



The median and the musculo cutaneous on the outer 

 side, the ulnar and internal cutaneous on the inner side, 

 the inner head of the median in front, and the musculo- 

 spiral and circumflex nerves behind. 



Landmarks of the Axilla. The lower border 

 of the pectoralis major corresponds to the line of the fifth 

 rib. The origin of the pectoralis minor corresponds to a 

 line drawn almost parallel to, and about three inches from, 

 the middle line of the sternum, from the third to the fifth 

 cartilages. The landmarks for the blood vessels are as 

 follows : for the axillary aiteiy> a line drawn from a 

 little to the inner side of the middle of the clavicle, to the 

 junction of the anterior and middle thirds of the antero- 

 posterior fold of the axilla, or, to the inner side of the 

 coraco-brachialis. or, when the arm is at right angles, to 

 midway between the two condyles. (Fig. 2.) 



