Carpal tunnel syndrome is caused by the compression of?

Appeared in: AIIMS BBSR SNO - 2019

Explanation

Carpal tunnel syndrome (CTS) is defined as an entrapment neuropathy caused by the compression of the median nerve at the wrist.
As shown in the provided diagram, the median nerve passes through the carpal tunnel, a confined space formed by the carpal bones and the transverse carpal ligament.
Compression in this tunnel leads to the characteristic symptoms of CTS: numbness, tingling, and pain in the median nerve distribution, which includes the thumb, index finger, middle finger, and the radial half of the ring finger.

Option B: The radial nerve is not located within the carpal tunnel. It runs along the thumb side of the forearm and provides sensation to the back of the hand.
Option C: The ulnar nerve passes through a different tunnel in the wrist called Guyon's canal. Its compression does not cause carpal tunnel syndrome.
Option D: The femoral nerve is a major nerve of the lower limb, located in the thigh. It has no anatomical connection to the wrist or hand.

Clinical Relevance

Nursing practice connection: Knowing Anatomy and pathophysiology of carpal tunnel syndrome helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses are crucial in assessing for CTS using provocative tests like Tinel's sign and Phalen's maneuver, and in educating patients about non-surgical management like wrist splinting and ergonomic changes.
Accurate identification of the affected nerve based on the pattern of sensory loss is a key nursing assessment skill to differentiate between various peripheral neuropathies.
What if? If a patient reported numbness primarily in their little finger and the adjacent half of their ring finger, the nurse should suspect ulnar nerve compression (Guyon's canal syndrome) rather than carpal tunnel syndrome.

How to Approach the Question

First, identify the core concept in the question: the cause of 'Carpal tunnel syndrome'.
Analyze the provided image. Note that it shows a cross-section of the wrist, explicitly labeling the 'Median nerve' passing through the 'Carpal tunnel'.
Evaluate the options based on this visual evidence and anatomical knowledge. The median nerve is the only nerve shown within the carpal tunnel.
Systematically eliminate the incorrect options. The radial and ulnar nerves have different pathways in the wrist. The femoral nerve is in the leg and is a clear distractor.
Conclude that the compression of the median nerve is the definitive cause of carpal tunnel syndrome, directly supported by the anatomical diagram.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 p. 1517-1519

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 4 p. 144-146

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