THE BREAST AND AXILLA 37 



lie on the first intercostal space ; others along the axillary 

 sheath ; while others are situated within the sheath in contact 

 with the vein. They receive the efferents of the subscapular, 

 pectoral, and central groups, and are connected, through the 

 costo-coracoid membrane, with the infra -clavicular lymph 

 glands in the superficial infra-clavicular triangle. The apical 

 lymph glands may become adherent to the axillary vein in 

 malignant disease and necessitate the excision of a part of that 

 vessel ; they may also press upon the cephalic vein, as it pierces 

 the costo-coracoid membrane in such a way as to render it 

 prominent throughout its course, in the arm. Efferents from 

 this group open into the lymph glands at the root of the neck, 

 and Halstead considers that these should be removed in the 

 routine operation for scirrhus mammae. 



The Posterior Wall of the Axilla is formed by the subscapularis, 

 teres major, and the tendon of the latissimus dorsi. 



The Subscapularis arises from the venter of the scapula and passes upwards 

 and laterally in front of the shoulder -joint to be inserted into the lesser 

 tubercle of the humerus and the capsule of the joint. It helps in adduction 

 and medial rotation of the arm and receives its nerve-supply from the upper 

 (short) and lower (middle) subscapular nerves (C. 5 and 6). 



The Latissimus dorsi (p. 269) is inserted into the floor of the intertubercular 

 sulcus of the humerus. It helps in extension, adduction, and medial rotation 

 of the arm and is supplied by the thoraco-dorsal (long subscapular) nerve 

 (C. 6, 7, and 8). 



The Teres major arises from the dorsal aspect of the inferior angle of the 

 scapula and runs upwards and laterally to be inserted into the medial lip 

 of the intertubercular sulcus. Its course corresponds to that of the latissimus 

 dorsi and its actions are therefore similar. It is supplied by the lower (middle) 

 subscapular nerve (C. 5 and 6). 



The great vessels and nerves of the axilla lie on the upper part of this 

 wall, and the subscapular vessels (p. 34) and the three subscapular nerves, 

 which all arise from the posterior cord, are closely related to it. 



The BRACHIAL PLEXUS and its important branches will be 

 considered in detail in a subsequent chapter (p. 95), but the 

 nerves must be identified as they surround the third part of the 

 axillary artery. The Median is recognised by its two heads 

 of origin and by its great size. The Musculo - Cutaneous is 

 recognised by its lateral position and by its deviation to reach 

 and pierce the coraco-brachialis. It is smaller than the median, 

 but occasionally it includes a large part of the lateral head of 

 the median, and the two nerves then tend to resemble one 

 another and can be distinguished only by their relative positions. 

 This part of the lateral head subsequently joins the median 

 nerve in the arm. 



Some difficulty may be experienced in distinguishing the 



36 



