136 SURGICAL ANATOMY OF THE AXILLA. 



and the dorsalis scapulae and anterior and posterior cir- 

 cumflex at the lower border of the subscapularis muscle. 



Besides the large nervous trunks, branches derived 

 from them are met with passing to the muscles covering 

 the several walls of the space. Thus, the anterior wall 

 is supplied by the loop formed round the first part of 

 the artery by the external and internal anterior thoracic 

 nerves, the inner wall by the posterior thoracic,.the pos- 

 terior wall by the subscapular, the outer by the circum- 

 flex and muscnlo-cutaneous. 



The lymphatic ganglia are very numerous, and lie, 

 some along the course of the vessels, and some along the 

 lower border of the pectoralis major. These ganglia re- 

 ceive the lymphatics of the upper extremity, back, and 

 posterior part of neck, the lateral lymphatics of the trunk, 

 those of the epigastrium and anterior part of thorax, and 

 mammary region. 



In order to gain a topographical idea of the position 

 of this vessel, in the first part of its course, i. e., between 

 the clavicle and the upper border of the pectoralis minor 

 muscle, it is best exposed from the front, by detaching 

 the clavicular attachment of the pectoralis major and 

 turning it down, when it will be found lying in a tri- 

 angle (the subdavicular\ which is bounded above by the 

 subclavius muscle, below by the pectoralis minor, and 

 internally by the thorax. Immediately beneath the de- 

 tached portion of the pectoralis major is a dense fascia 

 (the costo-coracoid membrane), a prolongation of the deep 

 cervical, passing beneath the clavicle, and attached to 

 the coracoid process and upper ribs, enveloping the pec- 

 toralis minor and binding down the axillary vessels in 

 a sort of sheath. From the lower border of the muscle 

 this aponeurosis descends, to be attached to that covering 



