Ulnar nerve injury commonly presents with which functional deficit?

• A. Weakness in grip strength and intrinsic hand muscle function
• B. Loss of dorsiflexion at the foot
• C. Loss of plantarflexion at the ankle
• D. Loss of knee extension

Answer: (A)

Ulnar nerve control in the hand is dominated by the intrinsic muscles that shape grip and fine motor function, including the interossei and the adductor pollicis. When this nerve is damaged, those intrinsic muscles weaken, leading to reduced grip strength and impaired intrinsic hand movements such as finger abduction/adduction and thumb adduction. This is why weakness in grip strength and intrinsic hand muscle function is the most characteristic functional deficit of ulnar nerve injury. In contrast, problems like loss of dorsiflexion at the foot, plantarflexion at the ankle, or knee extension involve other nerves (peroneal, tibial, and femoral, respectively) and not the intrinsic hand muscles.