Damage to which nerve would account for inability to oppose the left thumb and left little finger after an abdominal surgery with antecubital IV access?

Damage to which nerve would account for inability to oppose the left thumb and left little finger after an abdominal surgery with antecubital IV access?

• A. Radial
• B. Ulnar
• C. Median
• D. Musculocutaneous

Answer: (C)

Opposition of the thumb is carried out mainly by the thenar muscles (opponens pollicis, abductor pollicis brevis, flexor pollicis brevis) supplied by the recurrent branch of the median nerve. When the median nerve is damaged, these muscles weaken or fail to contract, so the thumb can’t be brought across the palm to touch the other fingers. This loss of thumb opposition is a classic sign of median nerve injury, which can occur with procedures or trauma in the cubital fossa area where antecubital IV access sits. Radial nerve injury would more likely cause problems with wrist and finger extension; ulnar nerve injury affects the little finger’s intrinsic hand muscles and can impair little-finger movements, but not primarily the thumb opposition. Musculocutaneous nerve injury affects forearm flexors and does not involve thumb opposition. Thus, the inability to oppose the thumb points to median nerve involvement.

Opposition of the thumb is carried out mainly by the thenar muscles (opponens pollicis, abductor pollicis brevis, flexor pollicis brevis) supplied by the recurrent branch of the median nerve. When the median nerve is damaged, these muscles weaken or fail to contract, so the thumb can’t be brought across the palm to touch the other fingers. This loss of thumb opposition is a classic sign of median nerve injury, which can occur with procedures or trauma in the cubital fossa area where antecubital IV access sits.

Radial nerve injury would more likely cause problems with wrist and finger extension; ulnar nerve injury affects the little finger’s intrinsic hand muscles and can impair little-finger movements, but not primarily the thumb opposition. Musculocutaneous nerve injury affects forearm flexors and does not involve thumb opposition.

Thus, the inability to oppose the thumb points to median nerve involvement.