12 



blood-vessels and the two or three branches of the N. radialis supplied to 

 the muscle (PI. II, e). Beneath this muscle the N. radialis gives off a small 

 branch to the extensor carpi obliquus (PI. II, f) ; this branch lies directly upon 

 the anterior-lateral face of the radius, at the side of the A. radialis anterior, 

 and beneath the deep face of the extensor digitalis communis which must 

 be turned aside sufficiently to expose the extensor carpi obliquus. Shortly 

 before the N. radialis passes beneath the extensor digitalis lateralis, close 

 to its origin, it gives off a small branch to this muscle (PI. II, g). 

 Slit open the aponetirotic sheath of the muscle and trace the branch some 

 little distance. Now transect the muscle at the level of the N. radialis 

 and trace the latter into the flexor carpi extemus where the nerve terminates 

 (PI. II, h). It will be seen from the above that the N. radialis supplies 

 the following muscles; the triceps (caput longiun, laterale and mediale), 

 the tensor fasciae antebrachii, the anconeus, the extensor carpi radialis, 

 the extensor digitalis communis, the extensor digitalis lateralis, the extensor 

 carpi obliquus, and the flexor carpi extemus, and one or more cutaneous 

 branches to the skin of the antebrachium. 



Blood-vessels of the Brachial Region 



The large V. axillaris and several of the vessels opening into it, viz., 

 V. thoracico-dorsalis from the deep pectoral muscles; the V. suprascapu- 

 laris, the V. thoracico-extema together with the branches from the latissi- 

 mus and pannictdus that communicate with the V. thoracico-extema a 

 short distance from its termination, have already been exposed. Additional 

 veins should be noted as they are uncovered in the further dissection. 



A. axillaris (PI. I, 21). Upon emerging from the thorax the A, axillaris 

 crosses the tendon of origin of the coraco-brachialis and the insertion of 

 the subscapularis, at the postero-intemal side of the scapulo-humeral 

 joint. From here the artey is continued by the A. brachialis (PI. I, 23) 

 which extends obliquely across the middle of the humerus to the antero- 

 intemal side of the distal third of the shaft of the bone where it divides 

 into two terminal branches — the A. radialis anterior and the A. radialis 

 posterior. 



Branches of the A. axillaris, 



A. cervicalis inferior. 

 A. suprascapularis. 

 A. subscapularis. 

 The A. cervicalis inferior and the suprascapularis have already been 

 traced, pp. 5, 8. The large A. subscapularis (PI. I, 22) arises from the 



