lO 



of the teres major in the angle formed by the Vv. subscapularis and 

 brachialis. Now sHt the posterior superficial pectoral longitudinally near 

 its middle. Turn aside the anterior portion of the muscle, together with 

 the posterior deep pectoral, in order to expose the Mm. coraco-brachialis 

 and the biceps brachii. 



N. musculo-cutaneous (PI. I, 29, 29') is a large nerve and originates from the 

 7th and 8th cervical nerves. Immediately after crossing the lateral face of 

 the A. axillaris (PL I, 21) a large portion of the nerve joins the N. medianus 

 by a large short branch that passes beneath the A. axillaris and with the 

 N. medianus forms a loop around it. Occasionally this nerve loop is 

 entirely wanting. From the loop thus formed, one or more branches are 

 given off to the superficial pectoral muscles as already demonstrated. The 

 larger portion of the N. musculo-cutaneous however, passes through the M. 

 coraco-brachialis (PI. I, 13, 29'), the overlying portion of which should be cut 

 just proximal to the nerve, and drawn aside. As the nerve enters the 

 coraco-brachialis it supplies a branch to it. Trace the main nerve through 

 the coraco-brachialis to its termination in the biceps brachii near to the 

 proximal end of the fleshy portion of the muscle (PL I, 29'). Theconnective 

 tissue and aponeurosis covering the vessels and nerves on the medial face 

 of the brachial region should now be removed. Note that here the vessels 

 and nerves have the following relations, viz., the N. medianus lies most 

 anteriorly and is followed in order by the A. brachialis, V. brachialis, N. 

 ulnaris, and finally, in the proximal part of the brachium, the large N. 

 radialis. Note also the small mass of lymph glands lying on the artery 

 and vein near the distal third of the brachium (PL I, 49')- 



N. radialis (PL I, 40) Ues posterior to the Nn. medianus and ulnaris and is 



the largest nerve of the brachial plexus. It originates from the 7th and 8th 

 cervical and the ist thoracic nerves, but principally from the 8th cervical 

 and I St thoracic. The nerve passes into the triangular space formed by 

 the tendon of the teres major and latissimus, the caput longum tricipitis 

 and the proximal end of the brachialis. An artery and vein also enter this 

 space and should be left intact. As the N. radialis enters the above men- 

 tioned triangular space it gives off several branches which are distributed 

 as follows: (a) one branch to the tensor fasciae antebrachii (PL I, 44). 

 To demonstrate this branch, transect the tensor fasciae antebrachii near 

 its distal third and turn the muscle aside but do not injure the nerve (a 

 branch of the N. ulnaris) which runs along the anterior border (PL I, a), 

 or sometimes crosses obhquely, the superficial surface of the distal 

 half of the muscle. Sometimes a small communicating branch passes from 



