72 THE UPPER EXTREMITY 



ridge, and extends up the arm as high as the insertion of 

 the deltoid. The dissector should note that these septa 

 divide the arm into an anterior and a posterior osteo-fascial 

 compartment. 



Structures in the Anterior Compartment. The anterior 

 osteo-fascial compartment of the arm has been opened into 

 by the reflection of the front part of the fascia brachii. 

 The three muscles which specially belong to this region are 

 the biceps brachii, brachialis, and the coraco-brachialis. The 



A. brachialis 



Sept. inter- _g 

 muse. med. "I 



N. ulnaris 



-, V. cephalica 



N. musculocutaneus 



L1-- A. profunda brachii 



i| - N. radialis .(musculo 

 j spiral) 



sJCT" M. brachioradialis 



y*" 1 Sept. intermus. lat. 



.' 



FIG. 30. Transverse section through the Distal Third of the 

 Right Arm. 



biceps brachii is the most superficial muscle : under cover of 

 it, and closely applied to the anterior aspect of the humerus, 

 is the brachialis ; whilst the coraco-brachialis is the slender 

 muscular belly which lies along the medial side of the biceps 

 in its upper part. But, in addition, two muscles of the fore- 

 arm will be observed extending upwards into this compartment 

 of the arm, to seek origin from the lateral epicondylar ridge 

 of the humerus : they are the brachioradialis and the extensor 

 carpi radialis longus. They are closely applied to the lateral 

 side of the brachialis. The brachial artery, with its venae 

 comites, extends through the region in relation to the medial 

 margin of the biceps brachii, and all the terminal branches of the 

 1>J7. T. W. FRAHM 



NO. 



