MYOLOGY. 05 



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

 into the inner or posterior edge of the bicipital groove, below the tendon 

 of the latissimus dorsi. It rotates the humerus inwards, adducts and draws 

 it downwards and backwards; it also draws forwards the inferior angle of 

 the scapula. 



The coraco-hrachialis arises from the point of the coracoid process and 

 from the tendon of the short head of the biceps ; descending obliquely for- 

 wards, it is inserted into the inner side of the humerus, a little below the 

 middle, and into the ridge leading to the internal condyle by an aponeurosis. It 

 serves to adduct, raise, and draw forward the arm ; also to rotate it outwards. 



Biceps is situated along the fore part of the humerus, and consists of two. 

 portions superiorly, the external or long, and the internal or short. The 

 internal arises from the coracoid process between the coraco-brachialis and 

 the triangular ligament ; the external or long head arises by a long tendon' 

 from the upper part of the glenoid cavity of the scapula; the two uniting 

 about the middle of the humerus in a large fleshy belly, which ends in a flat 

 tendon to be inserted into the back part of the tubercle of the radius. A 

 process from the anterior and outer border of this tendon, called the semi- 

 lunar fascia, passes to the internal condyle and to the aponeurosis of the 

 forearm. Its use is to flex the forearm and stretch its fasci«; also to 

 abduct and raise the arm. 



Brachialis anticus or extcrniis arises from the centre of the humerus by 

 two fleshy slips, one on either side of the insertion of the deltoid ; it m 

 inserted by a strong tendon into the coronoid process of the ulna and into 

 a rough surface on this bone beneath that process. Use : to flex the fore- 

 arm, also to strengthen the articulation when extended. 



Triceps extensor cubiti covers the back of the humerus, and extends from 

 the scapula to the olecranon ; it consists superiorly of three portions, the 

 middle or long, the second or external, and the third or internal or short 

 head {brachialis internus or posticus). The long or middle head arises 

 from the lower part of the neck of the scapula ; the second arises imme- 

 diately below the insertion of the teres minor from and behind a ridge on 

 the outer side of the humerus, commencing below the great tuberosity and 

 leading down to the external condyle ; the third or short head arises on the 

 inside of the humerus above its centre. These three portions unite above 

 the middle of the arm, and descending, terminate in a broad tendon of two 

 laminae, a superficial and a deep ; the former is continued into the fasciae 

 on the back part of the forearm, the latter is inserted into the posterior 

 border but not the point of the olecranon. Use: to extend the forearm on 

 the arm, by its long portion to carry the arm backwards, and in some cases 

 to abduct it. The triceps is thus the great extensor of the elbow joint," 

 while the biceps and brachialis anticus are the antagonist flexors. The 

 flexors thus predominate over the extensors, the contrary being tlie case in 

 the knee joint. 



2. Muscles of the Forearm. As these muscles are very numerous, they 

 will be most conveniently described by classing them according to theit 

 situations and use. One set is employed in bending the forearm, wriöt; 



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