5 6 THE UPPER EXTREMITY 



branch to the teres minor, and, after furnishing a few twigs 

 to the posterior part of the deltoid, is continued onwards, 

 as the lateral cutaneous nerve of the arm, which has already 

 been dissected in the superficial fascia over the lower part 

 of the deltoid (Fig. 22). The nerve to the teres minor is 

 distinguished by the presence of an oval gangliform swelling 

 upon it. 



The anterior division proceeds round the humerus with the 

 posterior circumflex artery of the humerus, and ends near the 

 anterior border of the deltoid. It is distributed by many 

 branches to the deep surface of this muscle, whilst a few 

 fine filaments pierce the deltoid and reach the skin. 



M. Teres Major. The part which the teres major plays in 

 the formation of the quadrilateral and triangular spaces has 

 already been seen. It arises from the oval surface on the 

 dorsum of the scapula close to the inferior angle of the 

 bone (Fig. 24, p. 55), and also from the septa which the infra- 

 spinous fascia sends in to separate it from the infraspinatus 

 and teres minor muscles. It is inserted into the medial 

 lip of the intertubercular sulcus on the upper part of the 

 humerus (Fig. 33, p. 79), and is supplied by the lower sub- 

 scapular nerve. 



Insertions of Latissimus Dorsi and Pectoralis Major. The narrow, 

 band-like tendon of the latissimus dorsi lies in front of the insertion 

 of the teres major. From its inferior margin a small fibrous slip will 

 be observed passing downwards, beyond the lower margin of the teres 

 major, to find attachment to the long head of the triceps (Fig. 22). This 

 is a rudiment of the dorsi-epitrochlearis muscle of the lower animals. The 

 tendons of the teres major and latissimus dorsi should now be separated from 

 each other. They will be found to be more or less adherent, and a small 

 bursa mucosa will be discovered between them. The insertion of the 

 latissimus dorsi into the bottom of the intertubercular sulcus of the humerus 

 may now be satisfactorily studied. 



The tendon of insertion of the pectoralis major, which is attached to the 

 lateral lip of the intertubercular sulcus, may also be conveniently examined at 

 this stage (p. 13). A separation of the sternal and clavicular portions of the 

 muscle will bring into view the two laminoe which constitute the tendon, 

 and the following points may be noted in connection -with these : (a) that 

 they are continuous with each other below, or, in other words, that the 

 tendon is simply folded upon itself ; (b) that the posterior lamina extends 

 upwards on the humerus to a higher level than the anterior, and that a 

 fibrous expansion proceeds upwards from its superior border, to seek 

 attachment to the capsule of the shoulder-joint and the lesser tuberosity of 

 the humerus ; (c) that the lower border is connected with the fascia of the 

 upper arm. 



Articulatio Acromio - Clavicularis (Acromio - clavicular 



