A patient with a radial nerve palsy after a mid-shaft humeral fracture managed conservatively is assessed at 12 weeks. Motor assessment uses the MRC scale. An MRC grade 3 for wrist extension indicates:

• A Full range of movement against gravity only, with no resistance ✓
• B Muscle contraction visible but insufficient to produce movement
• C Full range of movement against moderate resistance
• D Reduced range of movement against gravity only

Explanation

The MRC (Medical Research Council) scale grades muscle power: Grade 0 (no contraction), Grade 1 (flicker/trace), Grade 2 (movement with gravity eliminated), Grade 3 (movement against gravity — full range against gravity only, no resistance), Grade 4 (movement against gravity + resistance — subdivided 4-, 4, 4+), Grade 5 (normal power against full resistance). MRC Grade 3 indicates adequate motor recovery to overcome gravity, which is the functional threshold for meaningful use. In radial nerve palsy, recovery typically progresses from Grade 1 proximally (brachioradialis first) to Grade 3 then 5 over 3–6 months.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.