CHAPTER 18 : The Joints of the wrist , hand and fingers

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THE CARPAL TUNNEL

Boundaries:

Anterior:

Flexor retinaculum

Posterior:

Carpal bones (lunate, triquetral, scaphoid, trapezoid)

Medial:

Hook of hamate, pisiform

Lateral:

Tubercle of scaphoid, ridge of trapezium

Contents:

 
 

The median nerve

All long flexor tendons of fingers and thumb

The synovial sheaths

Connective tissue

 

 
 
 

Note:

  • The four tendons of the superficial flexor are separate and lie in two rows, with the middle and ring finger tendons in front of the index and little finger tendons.

  • The tendons of flexor digitorum profundus lie deeply in one plane.

  • All the eight tendons (of superficialis and profundus) share a common flexor sheath.

  • The tendons of flexor policis longus lies in its own synovial sheath.

  • At the lateral end of the tunnel a deep lamina from the flexor retinaculum is attached to the medial lip of the groove on the trapezium.

  • The tendon of flexor carpi radialis, enclosed in its own synovial sheath, runs in the groove in this subcompartment of the carpal tunnel.

  • The median nerve passes deep the flexor retinaculum between the flexor digitorum superficialis tendon to the middle finger and the flexor carpi radialis.

Carpal tunnel syndrome:

Compression of the median nerve in the carpal tunnel due to arthritic changes in the wrist joint, synovial sheath thickening or edema. Symptoms:

  • Impaired sensation over three and half digits on the thumb side
  • Wasting and weakening of thenar muscles
 
Lunate
scaphoid