Thursday, July 12, 2007

The Wrist & Repetitive Strain Injuries

Tips for preventing wrist injuries ...

"The wrist joins the hand to the forearm. It is able to move forward and back, side-to-side, and in circular movements. This variety of motion allows the hand to reach objects and function in a wide range of motion. In addition, a strong and stable wrist is important during grip activities.

The wrist is a complex joint where the two long bones of the forearm meet the eight small carpal bones of the wrist. These carpal bones are essentially arranged in two rows of 4 bones. The eight small wrist bones then meet the five long finger bones in the palm of the hand. Most of the muscles that move the wrist, fingers and thumb are located in the forearm. The tendons (the cords that connect muscle to bone) that bend and straighten the wrist and the fingers must cross through the wrist joint on their way from the elbow towards the hand.

Many of the repetitive strain injuries associated with computer work occur at the wrist. In fact, according to the National Occupation Research Agenda for Musculoskeletal Disorders, the most frequently reported upper-extremity musculoskeletal disorders affect the hand and wrist region.

Carpal Tunnel Syndrome is the most commonly diagnosed nerve injury in the arm. The nerves are the power cords for the arms, providing strength to the muscles and sensation to areas of skin. Carpal tunnel syndrome is the compression of the median nerve as the wrist as it passes from the neck to the fingers. Carpal Tunnel Syndrome can cause pain at the base of the hand and in the bulky muscles in the palm right below where the thumb meets the palm. Also, people often say they feel as if they have a tight band around their wrists. Numbness in the thumb, index and middle fingers is common. The pain may feel as if it is traveling up the arm and into the shoulder and neck

Pain where the thumb meets the wrist may be caused by a tendinitis of the muscles that pull the thumb back (as if you were hitchhiking). People who type tensely are prone to developing this tendinitis as they hold their thumbs over the keyboard with tension. Pain at the base of the thumb can also be caused by arthritis in the joint where the long palm bone meets one of the tiny wrist bones of the thumb.

Tendinitis of the wrist and finger flexors (the bending/closing muscles) and extensors (the straightning muscles) and benign ganglion cysts also occur fairly frequently at the wrist.

RSI Prevention

Maintain a neutral wrist position.

• The wrist should be flat in relationship to the forearm; it should not be bent forward or back.

• For each 15 degrees that the wrist is out of alignment, the pressure on the median nerve increases.

• The middle finger should be in alignment with the forearm, not angled toward the thumb or the small finger."    (Continued via Marji Hajic, Bella Online)
[Ergonomics Resources][Visit Ergonomics Store for Wrist Supports]

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