A 22-year-old man is admitted to the hospital after a car collision. Radiographic examination reveals an oblique fracture of his humerus. Upon physical examination the patient is unable to extend his forearm. The damaged nerve was most likely composed of fibers from which of the following spinal levels?
High-Yield Explanation
The radial nerve acts to extend the forearm at the elbow. This nerve is derived from all the roots of the brachial plexus C5 to T1. None of the other answers include all the roots and are therefore incorrect.