This document discusses the brachial plexus and muscle testing at different neurological levels from C5 to T1. It provides details on muscles innervated, reflex and sensation testing, and functions at each level. Specifically, it notes that C5 controls the deltoid and biceps muscles, C6 controls wrist extensors, C6 and C7 both innervate the biceps, and C7 controls triceps, wrist flexors and finger extensors. C8 governs finger flexors. A summary is then provided listing the motor and sensory levels from C5 to T1.