Carpal Tunnel Syndrome - Introduction

Introduction

Carpal tunnel syndrome (CTS) is a disorder marked by weakness and pain in the hand and wrist. CTS occurs in the nerves of the hands -- not the muscles, as some people believe. The symptoms of CTS can be incapacitating.

The Carpal Tunnel and Median Nerve

To understand how carpal tunnel syndrome arises, it is important to know the parts of the hand and wrist that are involved.

The Carpal Tunnel. The carpal tunnel is a passageway that forms beneath the strong, broad transverse ligament. This ligament is a bridge that extends across the lower palm and connects the bones of the wrist (carpals), which form an arch below the tunnel.

The Median Nerve and Flexor Tendons. The median nerve and nine flexor tendons pass under the ligament bridge and through the carpal tunnel (similar to a river). They extend from the forearm and up into the hand:

• The flexor tendons are fibrous cords that connect to muscles of the fingers (two to each finger) and one to the thumb. They allow flexing of the fingers and clenching of the fist.
• The median nerve plays two important roles. It supplies sensation to the thumb, index, middle, and ring fingers, and to the flexor tendons. It provides function for the muscles at the base of the thumb (the thenar muscle).

The Carpal Tunnel Syndrome Process

It is not completely known how the process leading to carpal tunnel syndrome actually evolves, and how nerve conduction (the passing of the nerve signal) through the wrist becomes changed. In general, carpal tunnel syndrome develops when the tissues around the median nerve swell and press on the nerve. Early in the disorder, the process is reversible. Over time, however, the insulation on the nerves may wear away, and permanent nerve damage may develop.

The following events have been observed in the hands of people with carpal tunnel syndrome: