A patient sustains a radial nerve injury in the radial groove of the humerus. Which movement is PRESERVED despite this high radial nerve lesion?

• A Extension of the elbow ✓
• B Extension of the wrist
• C Extension of the fingers at the metacarpophalangeal joints
• D Abduction of the thumb

Explanation

The branch to the triceps (elbow extensor) arises from the radial nerve in the axilla — proximal to the radial groove — and sometimes also from the spiral groove itself but at a level that is spared in most mid-shaft humeral fractures. Therefore, elbow extension via triceps is commonly preserved in radial groove injuries, even though wrist drop and loss of finger and thumb extension occur. This differentiates a mid-humeral radial nerve lesion from a posterior cord lesion at the axilla, where triceps is also paralysed.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.