48 



DISSECTION OF THE ARM. 



superior 

 prof un da, 



inferior 

 profunda, 



artery to 

 bone, 



and anas- 

 toinotic. 



Veins end in 

 the axillary. 



Nerves on 

 front of arm. 



Median 

 nerve with 

 the artery 



has not any 

 branch. 



and the anastomotic branch. The superior and inferior pro- 

 funda and the anastomotic branches of the brachial form a free 

 anastomosis about the elbow-joint with various arteries of the 

 forearm, and the accompanying scheme (fig. 19) represents the 

 general arrangement. 



The superior profunda branch ( 5 ) is larger than the others, and 

 leaves the artery near the lower border of the teres major ; it winds 

 backwards with the musculo-spiral nerve to the triceps muscle, and 

 will be dissected with the back of the arm (p. 53). 



The inferior profunda branch ( G ) arises opposite the coraco- 

 brachialis muscle, and accompanies the ulnar nerve to the interval 

 between the olecranon and the inner condyle of the humerus. 

 There it anastomoses with the posterior ulnar recurrent and anasto- 

 motic branches, and supplies the triceps. It often arises in common 

 with the superior profunda artery. 



The medullary artery of the humerus arises near the inferior 

 profunda, generally associated with various muscular branches, and 

 enters the aperture about the middle of the humerus, being directed 

 downwards. 



The anastomotic branch (') arises one or two inches above the 

 elbow, and its main branch courses inwards through the inter- 

 muscular septum to the hollow between the olecranon and the 

 inner condyle of the humerus. Here the artery anastomoses with 

 the inferior profunda and posterior ulnar recurrent branches, and 

 gives twigs to the triceps muscle ; one of the offsets forms an arch 

 across the back of the humerus with a branch of the superior 

 profunda. 



Before passing through the intermuscular system the artery sends 

 an offset to the pronator teres muscle in front of the internal condyle, 

 which joins the anterior ulnar recurrent vessel. 



The BRACHIAL VEINS (fig. 20, d) accompany the artery, one on 

 each side, and have branches of communication across that vessel ; 

 they receive tributary veins corresponding to the branches of the 

 artery. Above, they usually join into one, which enters the 

 axillary vein near the subscapular muscle. 



NERVES OF THE ARM (fig. 20). The nerves on the front of 

 the arm are derived from the terminal cords of the brachial 

 plexus. They furnish but few offsets above the elbow, b.eing 

 for the most part continued to the forearm and the hand. 

 The cutaneous branches of some of them have been already 

 referred to (p. 42). 



The MEDIAN NERVE (') arises from the brachial plexus by two 

 heads, one from the outer, and the other from the inner cord 

 (fig. 7, p. 23), and accompanies the brachial artery to the forearm. 

 Beginning on the outer side of the artery, the nerve crosses over 

 (sometimes under) it near the middle of the arm, and is placed on 

 the inner side a little above the elbow. It does not give any branch 

 in the arm ; but there may be a fasciculus connecting it with the 

 musculo-cutaneous nerve. Its relations to muscles are the same as 

 those of the artery. 



