An Introduction to the Carpal Tunnel

In the human wrist there is a sheath of tough connective tissue which envelopes and protects the median nerve and tendons. It is attached to the muscles, wrist and hand bones. It is called the carpal tunnel, which refers to the space between the sheath above and the bones below making up the wrist and hand.

The term carpal tunnel is also used quite commonly to refer to carpal tunnel syndrome. It is a condition where the median nerve is pinched within the tunnel.  This may cause pain and may also result in numbness of the wrist or hand.  Frequently, carpal tunnel is the result of repetitive motion such as painting or typing. Continuous flexing or stressing over a period of time causes pressure on the median nerve that carries nervous impulses back and forth between the hand and the spinal cord.

While it is commonly thought that repetitive motion over a long period of time results in carpal tunnel syndrome, the reality is that repetitive motion even over short periods of time - often just a few days - can cause carpal tunnel symptoms.

Carpal tunnel is a fibro-osseous tunnel on the palmar surface of the carpal bones. It transmits a number of tendons and the median nerve from the forearm into the hand. Surface markings are proximally the distal wrist crease or distally the hook of the hamate bone.

Both base and walls of the carpal tunnel are a concave bony channel that is formed by the carpal bones. It is the flexor retinaculum or transverse carpal ligament that forms the roof of the carpal tunnel. It attaches to the scaphoid tubercle and ridge of the trapezium laterally, to the pisiform and hook the hamate medially.

The recurrent thenar branch of the median nerve, the motor branch to the thenar eminence, leaves the median nerve in or beyond the carpal tunnel. It curves back over the flexor retinaculum to reach the thenar eminence.

The carpal tunnel transmits to only one nerve, the median, and nine tendons. They are the following: flexor digitorum superficialis which contributes to the four tendons that insert on the middle phalanx; flexor digitorum profundus which contributes to the four tendons that insert on the distal phalanx; flexor pollicis longus; palmaris longus which is a tendon merging with palmar aponeurosis; flexor retinaculum; flexor digitorum superficialis; flexor pollicis longus; flexor digitorum profundus and skin.

Therefore, the carpal tunnel is important because the median nerve can be compressed and result in carpal tunnel syndrome, wrist dislocations (result of this is that you cannot entirely move your fingers and hands), and small bone fractures. If the fragments remain in improper alignment there may be a need for surgical treatment before the carpal tunnel syndrome will be relieved.

This article is provided courtesy of Roxanne Courtmanch.  Please visit www.thehelpingcircle.com for more articles on carpal tunnel as well as many other topics that may be of interest to you.

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