Which nerve root corresponds to finger abduction of the medial arm?

Which nerve root corresponds to finger abduction of the medial arm?

• A. T1
• B. C8
• C. C7
• D. L5

Answer: (A)

Finger abduction in the hand is carried out by the dorsal interossei, which are innervated by the deep branch of the ulnar nerve. The motor fibers for these intrinsic hand muscles come from the lower trunk roots C8 and T1 of the brachial plexus. So the root most closely associated with this movement lies in the C8–T1 range, with T1 commonly used as the representative single root for this specific hand function. The other roots listed don’t supply these intrinsic hand muscles: C7 is more involved with forearm and arm outflow, and L5 is a lumbar/rooting level for the leg.

Finger abduction in the hand is carried out by the dorsal interossei, which are innervated by the deep branch of the ulnar nerve. The motor fibers for these intrinsic hand muscles come from the lower trunk roots C8 and T1 of the brachial plexus. So the root most closely associated with this movement lies in the C8–T1 range, with T1 commonly used as the representative single root for this specific hand function. The other roots listed don’t supply these intrinsic hand muscles: C7 is more involved with forearm and arm outflow, and L5 is a lumbar/rooting level for the leg.