sentence: the c6 nerve root shares a common branch from c5 , and has a role in innervating many muscles of the rotator cuff and distal arm , including : subclavius supraspinatus infraspinatus biceps brachii brachialis deltoid teres minor brachioradialis serratus anterior subscapularis pectoralis major coracobrachialis teres major supinator extensor carpi radialis brevis extensor carpi radialis longus latissimus dorsi damage to the c6 motor neuron , by way of impingement , ischemia , trauma , or degeneration of nerve tissue , can cause denervation of one or more of the associated muscles .