What is the Carpal Tunnel? (Carpal Tunnel Anatomy and Description)







The median nerve, radial artery, flexor tendons and blood vessels are contained within the confined space of the carpal tunnel.The carpal tunnel, which is located in the wrist joint, is a narrow passageway in which the nine flexor tendons and median nerve pass through in order to supply function, feeling and movement to the thumb, index, middle and one-half of the ring finger.

The finger / wrist flexor muscles and their tendons originate in the forearm at the medial epicondyle of the elbow joint and attach to the Metacarpal bones and first phalange (MP joint) and the first phalange and second phalange (PIP joint) and the second phalange and the third phalange (except for the thumb), which make up the distal (DIP) joint.

As the flexor muscles contract to bend the fingers downward into flexion towards the palm of the hand, the flexor tendons slide through the confined space within the carpal tunnel. The median nerve travels through the carpal tunnel alongside the flexor tendons and then divides into a motor branch that controls the thumb flexor and adductor muscles and sensory branches that provide over half the hand with the sensory of touch.

The eight rigid carpal bones on the posterior (back) of the wrist form one-half of the carpal tunnel / canal, while the transverse carpal ligament is positioned on the anterior (front) side of the wrist forms the remaining half. The size of the carpal tunnel is about the size of the index finger in diameter, and the flexor tendons and median nerve glide past each other with ease within the carpal tunnel when it is of sufficient size. But in such a small, confined space, especially if it is not stable or is collapsing due to a lack of extensor/abductor muscle strength supporting the carpal bones, the median nerve can become impinged by the collapsing structures, and over time, severely damage the function of the median nerve. If the tendon size increases due to inflammation or hypertrophy (growth), or if the carpal tunnel size decreases in size due to laxity in the joint, the structures within the carpal tunnel become impinged and carpal tunnel syndrome results.

National statistics show that Carpal Tunnel Syndrome has reached epidemic levels and if not addressed, will rise to pandemic proportions, costing the United States more than 100 billion annually in lost time from work, job retraining, decreased productivity levels, therapy and/or surgery.

Muscle Imbalance and the Narrowing of the Carpal Tunnel

Although increased size / *hypertrophy of the tendons can occur, the most prevalent cause of carpal tunnel syndrome is the **narrowing of the carpal tunnel due to a musculoskeletal imbalance between over and underused muscles in the hand and forearm. Once the carpal tunnel begins to collapse in on itself, any form of repetitive or static flexion such as typing, writing, grasping, etc., will cause friction of the flexor tendons against the carpal bones, median nerve and blood vessels, causing irritation, inflammation and increased swelling of the structures within the carpal tunnel.

*Muscle & Tendon Hypertrophy

The carpal tunnel consists of eight carpal bones that form the ceiling, while the floor is made up of the transverse carpal ligament. (Shown as Opposite in Image.)

The size of the flexor tendons can increase in size due to increased activity of the flexor muscles / tendons during activities such as gripping, typing, etc.

These activities directly exercise and strengthen the flexor muscles / tendons, causing them to become shorter and thicker, than normal, resulting in decreased space within the carpal tunnel and the compression of the median nerve and blood vessels.

The solution to reducing the size of the flexor tendons is to stretch and lengthen the flexor muscles / tendons, resulting in increased space within the carpal tunnel and the elimination of the impingement of the median nerve and associated vessels.

Equality of Muscle Strength and Muscle Length

The most common reason for compression of the median nerve is a result of the carpal tunnel collapsing inward. This is thought to be caused by a muscle imbalance that results from long, weak extensor muscles not begin able to hold the carpal bones in position or the extensor muscles ability to withstand the tremendous pull from the flexor muscles.

The most effective treatment to eliminate the muscle imbalance is to stretch and lengthen the flexor muscles and strengthen and shorten the extensor muscles to create equality of length and strength of the muscles within and around the carpal tunnel, which in turn stabilizes the carpal bones in their proper position, keeping them from collapsing into the carpal tunnel.

It is important to understand that performing any unidirectional movement pattern on a constant bases, whether static or repetitious in nature, can cause muscle imbalances throughout the entire upper extremity, affecting the fingers, hands, wrists, forearms, elbows, upper arms and shoulders, but these imbalances can be corrected with the appropriate training program.

In order to provide immediate and long-term relief, it is suggested that implementing the medically proven FLEXTEND® training systems into any upper extremity prevention or rehabilitation program will correct these Carpal Tunnel Syndrome and other musculoskeletal disorders affecting the upper extremity. (Consult your physician before beginning any type of exercise program.)