A patient with classic carpal tunnel syndrome undergoes examination. Sensation is diminished over the index, middle and half of the ring fingers, yet the skin over the central thenar eminence is completely normal. Why is sensation here spared?
- A It is supplied by the recurrent motor branch of the median nerve
- B It is supplied by the digital branches of the radial nerve crossing the wrist
- C The palmar cutaneous branch of the median nerve arises proximal to the flexor retinaculum and does not enter the carpal tunnel ✓
- D It receives dual supply from the lateral cutaneous nerve of the forearm
Correct answer: C. The palmar cutaneous branch of the median nerve arises proximal to the flexor retinaculum and does not enter the carpal tunnel
Explanation
The palmar cutaneous branch of the median nerve leaves the main trunk about 5 cm above the wrist, pierces the antebrachial fascia and passes superficial to the flexor retinaculum to supply the central palm and thenar skin. Because it bypasses the carpal tunnel, it escapes compression, and normal thenar eminence sensation helps confirm the lesion is at the tunnel rather than more proximally.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.