Final answer:
The median nerve is the nerve that is damaged and results in weakness in flexing the wrist and flexion of digits 1-3 when making a fist.
Step-by-step explanation:
The nerve that is damaged in this case is the median nerve, which results in weakness in flexing the wrist and flexion of digits 1-3 when making a fist.
The thenar muscles are affected, as they are responsible for flexing the thumb and play a key role in precise movements of the hand.