42 



DISSECTION OF THE AKM. 



Cephalic 

 vein. 



Superficial 

 lymphatics 



and glands. 



Superficial 

 nerves. 



External 

 cutaneous 

 nerves : 



two from 

 musculo- 

 spiral ; 



and mus- 

 culo-cuta- 

 neous. 



Internal 



cutaneous 



nerves, 



large 



and small 



the inner border of the biceps muscle to the middle of the arm, 

 where it passes beneath the deep fascia, and is continued into the 

 axillary vein. In this course it lies to the inner side of the brachial 

 artery. 



The CEPHALIC VEIN is derived chiefly from the external branch 

 of the median, for the radial vein is oftentimes very small ; it is 

 continued to the shoulder along the outer side of the biceps, and 

 sinks between the deltoid and pectoral muscles to open into the 

 axillary vein near the clavicle. 



The superficial lymphatics of the arm lie for the most part along 

 the basilic vein, and enter the glands of the axilla. A few lym- 

 phatics accompany the cephalic vein, and end in the upper axillary 

 glands. 



One or more superficial lymphatic glands are commonly found a 

 little above the inner condyle of the humerus. 



CUTANEOUS NERVES (fig. 15). The superficial nerves of the 

 arm appear on the inner and outer sides, and spread so as to cover 

 the surface of the limb. With one exception (intercosto-humeral), 

 all are derived from the brachial plexus, either as distinct branches, 

 or as offsets of other nerves. On the outer side of the limb are 

 branches of the musculo-spiral and musculo-cutaneous nerves. On 

 the inner side are two internal cutaneous nerves from the plexus, a 

 third internal cutaneous from the musculo-spiral, and the intercosto- 

 humeral nerve. 



The EXTERNAL CUTANEOUS BRANCHES OP THE MUSCULO-SPIRAL 



NERVE are two in number, and appear at the outer side of the 

 limb about the middle. The upper small one turns forwards 

 with the cephalic vein, and reaches the front of the elbow, 

 supplying the anterior part of the arm. The lower and larger 

 pierces the fascia somewhat farther down, and, after supplying 

 some cutaneous filaments to the back of the arm, is continued to 

 the forearm. 



The MUSCULO-CUTANEOUS NERVE pierces the fascia in front of 

 the elbow ; it lies beneath the median-cephalic vein, and divides 

 into branches for the forearm. 



The INTERNAL CUTANEOUS NERVE perforates the fascia in two 

 pieces, or as one trunk that divides almost directly into two. Its 

 anterior branch passes beneath the median-basilic vein to the front 

 of the forearm ; and the posterior winds over the inner condyle of 

 the humerus to the back of the forearm. 



A slender offset of the nerve pierces the fascia near the axilla, 

 and reaches as far, or nearly as far, as the elbow; it supplies the 

 integuments over the biceps muscle. 



The NERVE OF WRISBERG (small internal cutaneous) appears 

 behind the preceding, and extends to the interval between the 

 olecranon and the inner condyle of the humerus, where it ends in 

 filaments over the back of the olecranon. The nerve gives offsets 

 to the lower third of the arm on the inner and posterior surfaces, 

 and joins above the elbow the posterior branch of the larger internal 

 cutaneous nerve. 



