A 16 year-old woman was injured 2 days ago when a load of lumber fell from a shelf, pinner her left forearm. The following signs and symptoms are noted on her left side:
She does not feel pinprick, touch, temperature differences, or vibration on the medial hand, little finger, and medial half of the ring finger
Sweating is absent in the same distribution as the sensory loss
Radial wrist extension and flexion and finger extension are normal strength on manual muscle test
She is unable to flex the middle and distal phalanges of the 4th and 5th digits, abduct or adduct her fingers, or adduct the hand
Where is the location of the lesion?