In our wrists there is a sheath of connective tissue which covers and protects a nerve and a few tendons. It is connected to the muscles, wrist and hand bones. This connecting tissue is refered to as the carpal tunnel. It is the space between the sheath above and the bones below making up the wrist and hand.
The words "carpal tunnel" are also used to commonly refer to what is now called the "carpal tunnel syndrome". It's a condition where the median nerve is pinched within the tunnel and can cause severe pain. It can also present itself as numbness of the wrist or hand. This syndrome was once thought to be caused by repetitive motions such as painting or typing. This is a painful condition which is exacerbated by continuous flexing or stressing of an apendage over a lengthy period of time. This ultimatly 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 tunnel on the surface of the carpal bones. It transmits a number of signals from tendons and the median nerve to the forearm into the hand.
Both base and walls of the carpal tunnel are a concave bony tunnel 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.
Surprisingly 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.
The carpal tunnel is important because the median nerve can, in vary serious cases, be compressed such as what was indicated above. Carpal tunnel syndrome, wrist dislocations (a result of this is that you cannot properly 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).
