The Carpal Tunnel is located at the wrist and is anteriorly composed by a deep arch. The carpal bones and the flexor retinaculum together creates the deep arch.

Carpal Tunnel

 

  • Medially the base of the carpal arch composes the carpal tunnel and laterally it is composed by the tubercles of the scaphoid and trapezium.
  • The flexor retinaculum is a thick connective tissue ligament that bridges the space between the medial and lateral sides of the base of the arch and converts the carpal arch into the carpal tunnel.
  • The 4 tendons of the flexor digitorum profundus, the 4 tendons of the flexor digitorum superficialis, and the tendon of the flexor pollicis longus go through the carpal tunnel, as does the median nerve.
  • The flexor retinaculum holds the tendons to the bony plane in the wrist and keeps them from “bowing”.
  • Free movement of the tendons in the carpal tunnel is eased by synovial sheaths, which surround the tendons. All the tendons of the flexor digitorum profundus and flexor digitorum superficialis are encompassed by just one synovial sheath: a different sheath surrounds the tendon of the flexor pollicis longus. The median nerve is anterior to the tendons in the carpal tunnel.
  • The tendon of the flexor carpi radialis is encompassed by a synovial sheath and goes through a tubular compartment created by the connection of the lateral aspect of the flexor retinaculum to the margins of a groove on the medial side of the tubercle of the trapezium.
  • The ulnar artery, ulnar nerve, and tendon of the buddy – maris longus enter the hand anterior to the flexor retinaculum and thus don’t go through the carpal tunnel. The tendon of the palmaris longus isn’t encompassed by a synovial sheath.
  • The radial artery enters dorsally around the lateral side of the wrist and is located adjacent to the external surface of the scaphoid.
  • The extensor tendons enter the hand on the medial, lateral, and posterior surfaces of the wrist in 6 compartments defined by an extensor retinaculum and lined by synovial sheaths:
    • The tendons of the extensor digitorum and extensor indicis share a compartment and synovial sheath on the posterior surface of the wrist.
    • The tendons of the extensor carpi ulnaris and extensor digiti minimi have individual compartments and sheaths on the medial side of the wrist.
    • The tendons of the abductor pollicis longus and extensor pollicis brevis muscles, the extensor carpi radialis longus and extensor carpi radialis brevis muscles, and the extensor pollicis longus muscle go through 3 compartments on the lateral surface of the wrist.

Clinical Relevance

Carpal Tunnel Syndrome

Usually afflicting people between the ages of 40 and 60, especially ladies, carpal tunnel syndrome causes tingling and pain in the hand and forearm due to soft tissue swelling and compaction of a nerve at the wrist.

The carpal tunnel is the narrow space formed by the bones of the wrist (carpal bones) and the powerful ligament that lies over them Nerves and tendons run by means of this tunnel. In carpal tunnel syndrome, the median nerve, which controls some hand muscles and sense in the thumb, index and middle fingers, is compressed where it passes through the tunnel. This causes painful tingling in the hand, wrist and forearm and frequently influences both hands. In girls the menopause certainly plays a part. Work including repetitive hand motions is a risk factor.

What Are The Causes?

Carpal tunnel syndrome occurs because the soft tissues within the carpal tunnel swell and press on the median nerve at the wrist. Such swelling may happen during pregnancy, as part of rheumatoid arthritis and after a wrist fracture. It may be a characteristic of RSI.

In most instances there isn’t any clear cut cause.

What Are The Symptoms?

Symptoms primarily influence the regions of the hand supplied by the median nerve, that’s the thumb, the index and middle fingers, the interior side of the ring finger, and the palm of the hand. Symptoms initially contain:

  • burning and tingling in the hand
  • pain in the wrist and up the forearm.
  • As the condition worsens, other symptoms may slowly appear including: numbness of the hand, weakened grasp, wasting of some hand muscles, especially at the base of the thumb.

Symptoms are generally more intense at night, and pain may interrupt sleep. Shaking the affected arm may temporarily alleviate symptoms, but the numbness may become constant if left untreated.

What Might Be Done?

The symptoms of carpal tunnel syndrome may be relieved temporarily by Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), or by wearing a wrist splint. Resting the hand and arm on a pillow regularly brings relief. Sometimes a corticosteroid injection under the ligament may reduce swelling. If symptoms continue or recur, operation may be urged to cut the ligament under local anaesthetic and release pressure on the nerve. After operation, most folks have no additional symptoms.