Brachial plexus Schema To longus colli and scalene muscles [C5, 6, 7, 8 Dorsal scapular nerve [C5) Contribution from C To phrenic To subclavius muscle(C5. 6) c56 ve[C5. 6,7) osterior Musculocutaneous C56,7 Axillary nerve Long thoracic nerve[C5. 6. 7) c56 56,7,8.T1 c56.78.T们 Posterior divisions Medial c8.T1 7.8.T1) Media: cutaneous nerve of arm(T1) Lower subscapular nerve[(C5, 6) Medial cutaneous nerve of forearm(C8, T1) Thoracodorsal(middle subscapular) nerve Medial cord C5,6 臂丛的组成:C58、T1臂丛的组成：C5—8、T1