The axillary nerve arises from the posterior cord of the brachial plexus and supplies the deltoid and teres minor muscles. The serratus anterior is supplied by the long thoracic nerve, which is derived from the roots at C5, C6, and C7. The pronator teres is supplied by the median nerve, which is derived from the medial and lateral cords. The musculocutaneous nerve to the biceps brachii arises from the lateral cord, and the suprascapular nerve to the infraspinatus arises from the upper trunk.