formed by anterior rami of C5-C8 and T1 spinal nerves
(2)位置location:斜角肌间隙----腋动脉周围
Scalene fissure--- surrounding axillary artery
三干Three trunks
The upper trunk is formed by the joining of rootC5,C6. The middle trunk is the continuation of root C7. The lower trunk is formed by the joining of root C8 and T1
(3)臂外侧下皮神经inferior lateral brachial cutaneous n. (4)前臂内侧皮神经medial antebrachial cutaneous n.
(5)前臂外侧皮神经lateral antebrachial cutaneous n. (6)正中神经median n.
(2)分支branch: Divided into three parts by overlying pectoralis minor First portion, above muscle-gives rise to superior thoracic
artery and thoracoacromial a. Second portion, behind muscle-gives rise to lateral thoracic a. Third portion, below muscle-gives rise to subscapular a. anterior and posterior humeral circumflex a. subscapular a then divides into thoracodorsal a. and circumflex scapular a.