To differentiate between median nerve injury and anterior interosseous nerve injury, which assessment should be conducted?

• A. Assess for mobility in the shoulder
• B. Assess for sensory changes in the C5 dermatome
• C. Assess for strength in wrist flexors
• D. Assess for temperature sensation in the palm

Answer: (B)

To differentiate between median nerve injury and anterior interosseous nerve injury, assessing sensory changes in the C5 dermatome is an effective method. The median nerve is responsible for sensation in specific areas of the hand, particularly the palmar side of the thumb, index, middle fingers, and a portion of the ring finger. In contrast, the anterior interosseous nerve, a branch of the median nerve, primarily innervates certain muscles (like the flexor pollicis longus and the deep flexor of the index finger) but does not carry sensory fibers. Therefore, an injury to the anterior interosseous nerve would result in weakness in specific muscle groups without significant sensory loss.

By assessing for sensory changes at the C5 dermatome, clinicians can ascertain the involvement of the median nerve. If there is sensory loss in the areas innervated by the median nerve but not in the C5 region, this indicates that the injury might be specific to the anterior interosseous nerve, sparing sensory function.

The other options do not provide the same clarity in differentiation between the two conditions. Mobility in the shoulder does not relate to the median nerve or anterior interosseous nerve specifically. Assessing strength in wrist flexors may not definit