Clinical localization · Core

Ulnar nerve: elbow, wrist or C8–T1?

Ulnar localization

Cross-check the across-elbow segment, DUC and non-ulnar muscles.

3 learning sectionsCompiled 2026-09-08English edition · Traditional Chinese available

01Elbow and wrist

  • Verify elbow posture, segment distance and reproducibility of focal slowing.
  • Guyon canal disease can be motor, sensory or mixed according to branch involvement; DUC is often spared.

02Hand and forearm

  • ADM and FDI offer different fascicular information. FCU and ulnar FDP assess more proximal branches.
  • Fascicular lesions may spare forearm muscles, so one normal muscle cannot exclude an elbow lesion.

03Test beyond one nerve

  • Median APB, radial EIP and MABC can help assess C8–T1 roots or the lower trunk.
  • Use SNAPs, paraspinals and the history together to distinguish preganglionic and postganglionic sites.

Related nerves

Ulnar nerveMedial antebrachial cutaneous nerve

Pause and explain

Explain in your own words: “Concordant abnormalities across different nerves in one myotome add more localization value than one hand muscle.” Then think of a situation in which it could be misinterpreted.

Show a review prompt

Martin–Gruber communication can mimic an ulnar proximal-to-distal CMAP drop.

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References and further reading

Educational synthesis; independent neuromuscular specialist review is pending. Publication dates and compilation dates are distinct. This is an original teaching synthesis; consult the source for complete methods and criteria.