MUSCLES OF THE POSTERIOR HUMERAL REGION 203 



with the latter; insertion, inner border and inner surface of 

 the humerus near its middle, between the triceps and the 

 brachialis anticus ; higher up some of its fibers are often inserted 

 into a fibrous band arching over the latissimus dorsi and teres 

 major tendons, and attached close to the small tuberosity. 

 It is usually pierced by the musculocutaneous nerve. 



Many varieties which seem to indicate it are formed of three 

 parts, viz.: (1) A superior short part, from the coracoid to 

 small tuberosity (M. coracocapsularis) to the capsule; (2) 

 middle part, corresponding to the muscle usually seen; (3) 

 inferior part, to the inner epicondyle or supracondylar process 

 (coracobrachialis minor). The middle part is most constant 

 in man, but is usually accompanied by a part of the third, 

 with the musculocutaneous nerve between them. It may 

 send a slip to the brachialis anticus or internal septum or 

 internal brachial ligament. 



M. brachialis anticus (brachialis internus, p. n.) rises from 

 the lower half of the front of the humerus, nearly the whole 

 of the internal intermuscular septum, and upper part of the 

 external; it embraces the deltoid insertion by two processes, 

 the outer of which is in the spiral groove as far as the upper 

 limit of the deltoid tubercle. It is adherent to the capsule of 

 the elbow-joint, and often sends a slip into it, and is inserted 

 into the inner part of the rough surface at the junction of the 

 coronoid process with the shaft of the ulna and to a part of 

 the tubercle of the ulna. 



The Muscles of the Posterior Humeral Region 



M. extensor or triceps extensor cubiti occupies the whole 

 posterior brachial region. Three heads are inserted into a 

 common tendon occupying the posterior surface of the muscle 

 from the middle of the arm to the elbow. The middle or long 

 head (anconeus longus anconeus was a term applied to any 

 muscle attached to the olecranon) rises from the inferior glenoid 

 tubercle of the scapula and adjacent portion of the axillary 

 border; this forms the middle and superficial part of the muscle 

 and ends on the inner margin of the tendon. The external 

 head (anconeus brevis) rises above the spiral groove and from 

 an aponeurotic arch of the external intermuscular septum 

 as it crosses it, extending to the teres minor insertion above, 



