30 TOPOGEAPHICAL ANATOMY OF 



M. TEICEPS BRACHli. — Two heads — the long and the medial — 

 of the triceps have already been examined. It will he noticed that 

 the long head is included in both the medial and lateral aspects 

 of the arm. 



Caput laterale. — The four-sided lateral head arises from the posterior 

 face of the crest of the greater tubercle and the deltoid tuberosity of 



Si. supraspinatus. 



-51. supraspinatus. 



M. subscapularis. -fej^ ( '^ |||— M. inlraspinatus. 



Fig. 17. — Proximal End of the Humerus, with Areas of 

 Muscular Attachment. 



the humerus. Some fibres are connected with the fascial investment of 

 the arm. The insertion is partly to the lateral face of the olecranon 

 and partly in common with the insertion of the long head. 



Mm. flexores digitorum 

 sublirais et profundus 



M. flexor carpi ulnaris, 

 M. flexor carpi radialis. 



M. extensor carpi ulnaris. 



Fig. 18. — Distal End of the Humerus, with Areas of Muscular Attachment. 



Dissection. — If the lateral head of the triceps be now reflected, the 

 brachial and anconeus muscles will be exposed. Some little difficulty 

 may be experienced in separating the anconeus from the triceps. 



The radial nerve, and the branch of the deep brachial artery that 

 accompanies it into the forearm, will also be displayed. 



M. BRACHiALis. — The brachial muscle is almost entirely fleshy, and 

 occupies the spiral groove (sulcus nervi radialis) that traverses the 

 lateral surface of the humerus. Its origin is from the posterior surface 

 of the humerus close to the head of the bone. It will be seen that the 

 muscle crosses the flexor aspect of the elbow joint and enters the fore- 

 arm, but its ultimate insertion into the radius and ulna cannot yet be 

 demonstrated. 



M. anconjEUS. — The fleshy anconeus i muscle lies under cover of 

 ' ajKwv (anoon) [Gr.J, the elbow. 



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