132 SURGICAL ANATOMY OF THE AXILLA. 



toralis major muscle, rounded and muscular, but becom- 

 ing short and tendinous as it approaches the humerus ; 

 posteriorly, the lower edge of the latissimus dorsi muscle ; 

 internally, the chest- wall; externally, the arm. The 

 axillary artery is readily felt along the external bound- 

 ary, and may be here compressed against the bone as it 

 lies in the third part of its course, and it will be ob- 

 served that this vessel follows the course of the arm in 

 whatever position it takes. The base is formed by the 

 integument, which is fully provided with hair-bulbs and 

 sebaceous follicles. 



As the axilla would, in most cases, be attacked surgi- 

 cally from below, that is, from its base towards its apex, 

 it will be found to be advisable to describe its relations 

 and contents as they would be met with in this direc- 

 tion. 



Dissection. The arm is to be raised to a right angle 

 with the trunk, and the palm of the hand turned for- 

 ward. The integument being removed along the boun- 

 daries of the base, the subcutaneous cellular tissue is first 

 met with, containing a good deal of reddish fat in its 

 meshes; next, an aponeurosis, which is continuous in 

 front with the sheath of the pectoralis major; behind 

 with that of the latissimus dorsi; externally with the 

 brachial aponeurosis, and internally with that covering 

 the serratus magnus. On removing this aponeurosis the 

 axillary space is opened ; a large quantity of loose fat 

 and cellular tissue and a quantity of lymphatic glands 

 are seen filling up the interspace between the thorax and 

 the arm. 



Lying in this cellular tissue, and bridging across from 

 the arm to the chest, will be seen a good many nerves, 

 the intercosto-humeral, which, in some subjects, form 



