What motor function is lost due to a radial nerve injury?

A radial nerve injury primarily affects the ability to extend the wrist and fingers, which is crucial for various hand functions. The radial nerve innervates the extensor muscles in the forearm responsible for wrist and finger extension. When this nerve is compromised, individuals often experience wrist drop, which severely limits the ability to extend at the wrist joint and impacts the extension of the thumb.

Since the wrist extension is lost, the individual may find it challenging to perform actions that require the wrist to be in an extended position. These actions include pushing or grasping objects. In addition, the loss of thumb extension also affects the ability to perform tasks that require thumb opposition and grip strength, further limiting functional use of the hand.