Carpal Tunnel

An Introduction to the Carpal Tunnel

In the human wrist there is a sheath of tough connective tissue which envelopes and protects one nerve, median and tendons. It is attached to the muscles, wrist and hand bones. It is called the carpal tunnel which is 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 and causes pain. It is also experienced in the numbness of the wrist or hand, once thought to be a result of repetitive motion such as painting or typing. This is a painful condition by continuous flexing or stressing over a lengthy period of time which is caused by pressure on the median nerve that carries nervous impulses back and forth between the hand and the spinal cord.

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. If the incision over the calpar tunnel is made to far laterally, it is dangerous making surgery.

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 in cases such as what was mentioned above, carpal tunnel syndrome, wrist dislocations (result of this is that you cannot entirely move your fingers and hands) and bone fractures (it is a minor injury in which the fragments remain not in proper alignment so there is a need for surgical treatments before it can be back to its normalcy).