Limbs : Upper Limb 85 



The tendon of Teres major has a clearly-cut marking on the inner lip, which 

 terminates at its lower end. 



The two lips of the groove mark the continuation on to the humerus of the planes of the front 

 and back walls of the axilla. The outer wall must therefore lie between the structures going to 



Jell- 



FIG. 67. The two planes of the Triceps. In "the first figure the inner head is seen as the deep 

 plane of the muscle ; observe the musculo-spiral nerve crossing the inner head to reach the 

 bone externally, a consequence of the height to which the origin of the head extends. In 

 the next figure the other heads are seen lying on the deep plane, and a piece of the long head is 

 cut away to show the musculo-spiral nerve lying at first between the long and inner heads 

 before passing between the inner and outer. The ulnar nerve is applied to the inner head 

 from the time it enters the arm, only separated from it by the musculo-spiral and superior 

 profunda. The Deltoid is indicated by thick lines ; the circumflex nerve appears between 

 long and outer heads deep to the muscle, so that each of its divisions must cross one of these 

 heads under cover of the Deltoid. 



these lips : the innermost of these intermediate tissues is the Coraco-brachialis, which thus comes 

 to form the outer wall of the axilla (Fig. 66). 



The anterior circumflex artery runs outwards from the axillary sheath in the neighbourhood 

 of the upper part of the I^atissimus dorsi tendon, thus reaching the floor of the bicipital groove on 

 this tendon. It runs at first deep to the median and musculo-cutaneous nerves, then passes behind 

 Coraco-brachialis and short head of Biceps, and in the groove is covered by the long head in its 



