64 ANTHROPOLOGY. 



Of these, one is connected to the clavicle {suhclavius\ two to the humerus 

 {pectoralis major and latissimus dorsi), and eight to the scapula, viz, trape- 

 ziics, levator anguli scapuloe, omo-hyoid., rliomboides majo7' and minor, 

 serratus magnus, pectoralis minor^ and latissimus dorsi. The muscles of the 

 upper extremity are classed into those of the shoulder and arm, forearm, 

 and hand. 



1. Muscles of the Shoulder and Arm. These muscles are hidden 

 from view by the supra-spinous, infra-spinous, and subscapular fasciae, and 

 the brachial aponeurosis, which have already been briefly described. The 

 proper muscles are six in number : the deltoid, supra and infra spinatus, 

 teres minor and major, and the subscapularis. Those of the arm are four : 

 the biceps, coraco-brachialis, brachialis anticus, and triceps. 



The deltoides is a very thick, strong, and triangular muscle, bent so as to 

 embrace the shoulder-joint in front, externally and behind. It arises from 

 the lower edge of the spine of the scapula and from the anterior edge of 

 the acromion process, and from the external third of the clavicle ; its in- 

 sertion is into a rough surface about two inches in extent situated on the 

 outer side of the humerus, and commencing just above its centre. It 

 abducts and raises the arm, draws it forwards or backwards, and rotates it 

 inwards or outwards. 



/Supra-spinatus fills the fossa of the same name, and arises from all that 

 portion of the scapula above its spine, as also from a strong fascia which 

 covers the muscle ; it is inserted into the upper and fore part of the great 

 tuberosity of the humerus, into the most anterior and superior of the three 

 depressions which are marked on that surface. It assists the deltoid in 

 raising and abducting the arm, strengthens the capsular ligament, and acts 

 as antagonist to the pectoral, deltoid, and other muscles in preventing a 

 tendency to dislocation. 



Infra -sjnnatus is inferior to the last, flat, and triangular. It arises from 

 the inferior surface of tlie spine of the scapula and from the dorsum of this 

 bone as far down as the posterior ridge on the inferior costa ; it is inserted 

 into the middle of the external or greater tuberosity of the humerus below 

 the infra-spinatus. Its use is to assist the superior part of the deltoid in 

 raising the arm, drawing it backwards, and rotating it outwards; it also 

 serves to strengthen the articulation. 



Teres minor is a small muscle inseparably attached along the lower edge 

 of the last muscle. It arises from a depression between the two ridges on 

 the inferior costa of the scapula, and is inserted below the infra-spinatus 

 into the inferior depression on the great tuberosity of the humerus, and into 

 the bone a little lower down. It co-operates with the last muscle. 



Sub-scapular is is a broad, triangular muscle, situated on the inner side ol" 

 the scapula opposite to the three last mentioned muscles. It arises from 

 all the surface and (>ircumference of the subscapular fossa, and is inserted 

 into the interval or small tubercle of the humerus. As the strongest of the 

 capsular muscles, it strengthens the inner side of the articulation and 

 guards against dislocation. 



Teres wMJor^ a long and flat muscle, arises from a rough flat surface on 

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