Carpal Tunnel Syndrome - Introduction

Introduction

Carpal tunnel syndrome (CTS) is a disorder that causes pain and weakness in the hand and wrist. CTS develops from problems in the nerves of the hands -- not the muscles, as some people believe. The symptoms of CTS can range from mild to 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) that form an arch below the tunnel.

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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 up into the hand:

• The flexor tendons are fibrous cords that connect the muscles in the forearm to 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 palm side of 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 transmission of the nerve signal) through the wrist changes. 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: