In cubital tunnel syndrome (ulnar nerve entrapment at the elbow), which muscle is typically spared even in advanced cases, helping to localise the lesion?

• A Flexor digitorum profundus (medial half)
• B Flexor carpi ulnaris is affected; all ulnar-innervated muscles are affected equally
• C Abductor digiti minimi
• D Flexor carpi ulnaris ✓

Explanation

In cubital tunnel syndrome at the medial epicondyle, the branch to flexor carpi ulnaris (FCU) arises very proximally from the ulnar nerve just at or above the level of the compression; additionally FCU receives a separate proximal branch. In practice, FCU is often relatively spared compared to the intrinsic hand muscles (hypothenar, interossei, medial lumbricals) and FDP, because the fibres destined for hand intrinsics occupy the more superficial/compressed position. Wrist flexion (FCU) is notably less affected than intrinsic hand muscle wasting, which helps localise to cubital tunnel rather than Guyon's canal (where FCU is always spared as its branch arose above).

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.