514 



NERVES OF THE ARM. 



at the pronator quadratus, it sends branches to that muscle, 

 and, passing between it and the interosseus ligament, perforates 

 the ligament, and soon terminates on the posterior side of the 

 wrist and hand. 



As the Median Nerve proceeds downwards, it becomes 

 more superficial ; and continuing among the tendons of the 

 flexors of the fingers, it giyes off a, branch called superficial 

 palmar which crosses the annular ligament and is principally 

 spent upon the integuments of the ball of the thumb and the 



Fig. 212.* 



palm of the hand. This great nerve 

 passes with the tendons under the an- 

 nular ligament ; and immediately after, 

 while it is covered by the Aponeurosis 

 Palmaris, and by that portion of the 

 artery which is called Arcus SubUmus, 

 it divides into six branches, one muscu- 

 lar and five digital, which separate from 

 each other at acute angles, and subdi- 

 vide so as to send a ramification to each 

 side of the thumb, one to the radial side 

 of the index, one which subdivides to 

 the adjoining sides of the index and 

 little finger, and one which branches in 

 like manner to the radial side of the 

 ring finger, and the ulnar surface of the 

 middle. The muscular branch goes to 

 the thumb. 



* Relation of the nerves and veins at the bend of the elbow. 1. The radial 

 vein. 2. The cephalic vein. 3. The anterior ulnar vein. 4. The posterior 

 ulnar vein. 5. The trunk formed by their union. 6. The basilic vein, piercing 

 the deep fascia at 7. 9. A communicating branch between the deep veins of 

 the fore-arm and the upper part of the median vein. 10. The median cephalic 

 vein. 11. The median basilic. 12. A slight convexity of the deep fascia, 

 formed by the brachial artery. 13. The process of fascia, derived from the 

 tendon of the biceps, and separating the median basilic vein from the brachial 

 artery. 14. The external cutaneous nerve, piercing the deep fascia, and divid- 

 ing into two branches, which pass behind the median cephalic vein. 15. The 

 internal cutaneous nerve, dividing into branches, which pass in front of the 

 median basilic vein. 16. The intercosto-humeral cutaneous nerve. 17. The 

 spiral cutaneous nerve, a branch of the musculo-spiral. 



