THE CIRCUJIFLEX NERVE. 



585 



upper and a lower branch, which are distributed to the deltoid and 

 teres minor muscles, the integument of the shoulder, and the shoulder- 

 joint 



Fig. 358. — Distribution op the Posterior Cutaneous ^'-- ^58. 



Nerves op the Shoulder and Arm (after Hirschfel 

 and Leveille). | 



1, supra-acroinial branches of the cervical nerves de- 

 scending on the deltoid muscle ; 2, ascending or reflected, 

 and 2', descending cutaneous branches of the circumflex 

 nerve ; 3, inferior external cutaneous of the musculo-spinil 

 nerve ; 4, external and posterior cutaneous branches of the 

 musculo-cutaneous nerve to the forearm ; 5, intei-nal 

 cutaneous of the musculo-spiral ; 6, intercosto-huraeral 

 branches ; 7, twigs of the nerve of Wrisberg ; 8, upper 

 posterior branch of the internal cutaneous nerve ; 9, lower 

 branch of the same. 



a. The upper portion winds round the upper part of 

 the humerus, extending to the anterior border of the 

 deltoid muscle, to which it is distributed. One or two 

 cutaneous flament.i, penetrating between the muscular 

 fibres, are bent downwards and supply the integument 

 over the lower part of the muscle. 



b. The lotfer branch supplies offsets to the back part 

 of the deltoid, and furnishes the nerve to the teres 

 minor, which is remarkable in presenting a gangli- 

 f orm enlargement. It then turns round the posterior 

 border of the deltoid below the middle, and ramifies 

 in the integuments over the lower two-thirds of that 

 muscle, one branch extending to the integument over 

 the long end of the triceps muscle. 



c. K-a. art icula r f lament for the shoulder- joint arises 

 near the commencement of the nerve, and enters the 

 capsular ligament below the subscapular muscle 



Varieties. — In two instances Tm'ner has described 

 a branch of the cii'cumflcx nerve which supplies the 

 teres major. (Joum. of Anat. vol. vi., p. 104.) 



Internal cutaneous nerve. — At its origin 

 from tlie inner cord of the brachial plexus, 

 this nerve is placed on the inner side of the axillary artery. It becomes 

 cutaneous about the middle of the arm, and after perforating the 

 fascia, or, in some cases, before doing so, is divided into two parts ; one 

 destined for the anterior, the other for the posterior surface of tlie 

 forearm. 



a. The anterior branch crosses at the bend of the elbow "behind (in some cases 

 over) the median basilic vein, and distributes filaments in front of the forearm, 

 as far as the wrist ; one of these is, in some instances, joined with a cutaneous 

 branch of the ulnar nerve. 



b. The posterior branch inclines obliquely downwards at the inner side of the 

 basilic vein, and winding to the back of the forearm, over the prominence of the 

 internal condyle of the humerus, extends somewhat below the middle of the fore- 

 arm. Above the elbow this branch is connected with the smaller internal 

 cutaneous nerve (nerve of AVrisberg), and afterwards communicates with the 

 outer portion of the internal cutaneous, and, according to Swan, with the dorsal 

 branch of the ulnar nerve. 



c. A branch to the integument of the arm pierces the fascia near the asilla,and 



