Carpal tunnel

The carpal tunnel is a fibro-osseous canal that acts as a passageway from the forearm to the anterior hand. It is found in the anterior wrist.

  • superficial border (roof): flexor retinaculum
  • deep border (floor): carpal groove (formed by palmar aspect of carpal bones)
  • medial/ulnar border: lateral surface of hamate
  • lateral/radial border: medial surface of trapezium
  • medial/ulnar: pisiform bone and hook of hamate
  • lateral/radial: scaphoid tubercle and ridge of trapezium

The carpal tunnel contains the following structures, from superficial to deep:

Note, the flexor carpi radialis is often wrongly stated to be within the carpal tunnel, its course is in fact between the superficial and deep layers of the flexor retinaculum itself within its own compartment.

The tendons within the carpal tunnel are surrounded by synovial sheaths. One which envelops the flexor digitorum superficialis and profundus together, and a separate sheath for the flexor pollicis longus.

On to the surface of the medial aspect is formed the Guyon's canal through which runs the ulnar nerve and artery (ulnar nerve more medial) superficial to the tunnel. More laterally the palmaris longus is attached on to the superficial surface. Palmar cutaneous branch of the medial nerve runs superficial. 

  • Origin: tubercle or scpahoid and ridge of trapezium
  • Insertion: pisiform and hook of hamata
  • Into it: palmaris brevis and palmaris longus, palmar aponeurosis
  • From it: thenar and hypothenar muscles 
  • Over it: ulnar artery and nerve, palmar cutaneous branch of the median nerve, palmar branch of the radial artery
  • Deep to it: as above 

Variant anatomical structures within the carpal tunnel 2:

Anatomy: Upper limb
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Article information

rID: 33161
Section: Anatomy
Synonyms or Alternate Spellings:

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