EXTERNAL CUTANEOUS NERVE. 



409 



others in the axilla. They are distributed to the subscapularis 

 muscle. 



The terminal branches of the plexus are F;O . 1325tt 



arranged in the following order : the external 

 cutaneous, and one head of the median to the 

 outer side of the artery ; the other head of the 

 median, internal cutaneous, and ulnar, upon 

 its inner side; and the circumflex and musculo- 

 spiral behind. 



The EXTERNAL CUTANEOUS NERVE (mus- 

 culo-cutaneous, perforans Casserii) arises from 

 the brachial plexus in common with the ex- 

 ternal head of the median; it pierces the 

 coraco-brachialis muscle and passes between 

 the biceps and brachialis anticus, to the outer . 

 side of the bend of the elbow, where it perfo- 

 rates the fascia, and divides into an external 

 and internal branch. / // , \\ 



These branches pass behind the median 

 cephalic vein and are distributed to the integu- 

 ment upon the outer side of the fore-arm as 

 far as the wrist, communicating with the in- 

 ternal cutaneous and radial nerves. From the 

 internal division at the lower third of the fore- 

 arm a branch is given off which accompanies 

 the radial artery to the wrist and supplies 

 several filaments to the synovial membranes 

 of the wrist, both on its anterior and posterior 

 aspect. 



The Branches of the external cutaneous 

 nerve in the upper arm are distributed to the 

 coraco-brachialis, biceps, and brachialis anti- 

 cus muscle. 



The INTERNAL CUTANEOUS NERVE is one of 



* The Brachial plexus of nerves with its branches and their distribution. 1. The 

 brachial plexus. 2. The short thoracic nerves. 3. The long thoracic or external 

 respiratory of Bell. 4. The phrenic nerve. 5. The supra-scapular nerve. 6. The 

 subscapular nerves. 7. The external cutaneous nerve. 8. The point at which it 

 pierces the coraco-brachialis muscle. 9. The internal cutaneous nerve : the point at 

 which it pierces the deep fascia. 10. The origin of the median nerve by two heads. 

 11. The bend of the elbow where the median passes between the two heads of the 

 pronator radii teres, and of the flexor sublimis digitorum. 12. Its muscular branches. 

 13. Its anterior interosseous branch. 14. The point at which the nerve passes beneath 

 the annular ligament and divides into six terminal branches. The branch which 

 crosses the annular ligament is the superficial palmar. 15. The ulnar nerve giving off 

 several muscular branches to the triceps. 16. The point at which it pass'es between 

 the two heads of the flexor carpi ulnaris. 17. Its dorsal branch. 18. The termination 

 of the nerve, dividing 1 into a superficial and deep palmar branch. 19. The musculo- 

 spiral nerve. 20. Muscular branches. 21. Spiral cutaneous nerve. 22. The posterior 

 interosseous nerve piercing the supinator brevis muscle. 23. The radial nerve. The 

 two last nerves are the terminal branches of the' musculo-spiral. 24. The point at 

 which the radial nerve pierces the deep fascia. 25. The circumflex nerve. 



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