250 DISSECTION OF THE ARM. 



passes beneath the deep fascia, and is continuous with the axillary vein. 

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



The cephalic vein (fig. 76, 2 ) 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, near the clavicle, to open into the axillary 

 vein. 



Fig. 76. 



1. Median basilic vein. 



2. Median vein of the forearm bifurcating. 



3. Anterior ulnar veius. 



4. Cephalic vein formed by radial from behind and the median 



cephalic in front. The musculo-cutaneous nerve is by the side 

 of it. 

 j. Basilic vein, with large internal cutaneous nerve by its side. 



6. Bi-achial artery, with its companion veins (one cut). 



7. Radial vein. 



CUTANEOUS VEINS AND NERVES AT THE BEND OF THE ELBOW. (Quain's " Arteries.") 



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

 basilic vein, and enter into the glands of the axilla. A few lymphatics 

 accompany the cephalic vein, and end as the others in the axillary glands. 



One or more superficial lymphatic glands are commonly found near the 

 inner condyle of the humerus. 



CUTANEOUS NERVES. 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, 

 large and small (from the plexus), a third internal cutaneous from the 

 musculo-spiral, and the intercosto-humeral nerve. 



EXTERNAL CUTANEOUS NERVES. The external cutaneous branches of 

 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 ante- 

 rior part of the arm. The lower and larger pierces the fascia somewliat 

 farther down, and after supplying some cutaneous filaments, is continued 

 to the forearm. 



The cutaneous part of 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. 



INTERNAL CUTANEOUS NERVES. The larger internal cutaneous nerve 

 perforates the fascia in two parts, or as one trunk that divides almost 



