This issue has not come up in an exam, as yet (at least not since 2000).

However, it may well appear one day. Median nerve injury is a common complication of botched brachial artery cannulation.

Course of the Median Nerve

Course of the Median Nerve

Lesions of the Median Nerve

Lesions above the elbow

  • Motor deficit:
    • Loss of pronation of forearm
    • Weakness in flexion of the hand at the wrist
    • Loss of flexion of thumb, 2nd and 3rd digits
    • Loss of abduction and opposition of thumb.
    • Fixed hyperextension of index finger, middle finger and thumb
  • Sensory deficit:
    • Loss of sensation in the thumb, 2nd and 3rd digits, and the thenar area.

Lesions between elbow and wrist

  • Motor deficit:
    • Loss of pronation of forearm
    • Loss of flexion of thumb, 2nd and 3rd digits
    • Loss of abduction and opposition of thumb.
  • Sensory deficit:
    • Loss of sensation in the thumb, 2nd and 3rd digits, and the thenar area.

Lesions proximal to the carpal tunnel

  • Motor deficit:
    • Loss of flexion of thumb, 2nd and 3rd digits
    • Loss of abduction and opposition of thumb.
  • Sensory deficit:
    • Loss of sensation in the thumb, 2nd and 3rd digits, and the thenar area.

Lesions within the carpal tunnel:

  • Motor deficit:
    • Loss of flexion of thumb, 2nd and 3rd digits
    • Loss of abduction and opposition of thumb.
  • Sensory deficit:
    • Loss of sensation in the thumb, 2nd and 3rd digits, but excluding the thenar eminence

References

For a reference, I direct the time-rich reader to Sir Sydney Sunderland's "Nerves and Nerve Injuries", from 1968. (Not available as full text in Google, unfortunately.)

For brachial plexus injuries, I recommend Alain Gilbert's book.

For peripheral nerves, there is Haymaker, Webb, and Barnes Woodhall. Peripheral nerve injuries: principles of diagnosis. Thieme, 1998.

Vanderpool, D. W., et al. "Peripheral compression lesions of the ulnar nerve."Journal of Bone & Joint Surgery, British Volume 50.4 (1968): 792-803.