In carpal tunnel syndrome, the median nerve at the wrist is compressed under the flexor retinaculum. The motor branch to thenar muscles (recurrent thenar branch) typically arises:

• A Just distal to the distal edge of the flexor retinaculum and curves radially (extracurricular or subligamentous origin) ✓
• B Before the median nerve enters the carpal tunnel (proximal to the flexor retinaculum)
• C At the mid-portion of the carpal tunnel
• D From the ulnar nerve in ~50% of individuals

Explanation

The recurrent motor branch of the median nerve most commonly (approximately 50%) arises extraligamentous (subligamentous), curving around the distal edge of the flexor retinaculum before entering the thenar muscles. In 30% it arises within the carpal tunnel (intraneural variant) and in 20% it pierces the retinaculum (transligamentous). This anatomical variability is critical during carpal tunnel release surgery — the recurrent branch must be identified and protected to avoid iatrogenic thenar palsy.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.