Wrist Joint: Anatomy, Function, Ligament, Movement

Introduction

The wrist joint is the joint where the hand and forearm meet. The wrist joint is made up of small bones called carpals, which are held together by ligaments, tendons, and muscles. The wrist joint is a complex joint that allows for a wide range of motion. The wrist joint is also the starting point for the hand and fingers, which are essential for human function and survival.

~Wrist joint is a synovial joint between lower end of radius and three lateral bones of proximal row of carpus.

Articular surfaces

*upper:
~Inferior surface of the lower end of the radius.
~articular disc of the inferior radioulnar joint.

*lower:
1.Scaphoid
2.Lunate
3.Triquetral bones

Ligaments of wrist joint

1. The articular capsule:

~it is surrounds the joint.it is attached above to the lower ends of the radius and ulna, and below to the proximal row of carpal bones.
~a protrusion of synovial membrane, called the prestyloid recess,lies in front of styloid process of the ulna and in front of articular disc.
~it is bounded inferiorly by a small meniscus projecting inwards from the ulnar collateral ligament between the styloid process and the triquetral bone.
~the fibrous capsule is strenghened by a following ligaments.

2. on the palmer aspect,

there are two palmar carpal ligments.

1.The palmar radiocarpal ligament:
~it is a broad band.it begins above from the anterior margin of the lower end of the radius and its styloid process,runs downwards and medially,and is attached below to the anterior surfaces
of the scaphoid,the lunate and triquetral bones.

2.The palmar ulnocarpal ligament:
~it is a rounded fasiculus.it begins above from the base of the styloid process of the ulna and the anterior margin of the articular disc,runs downward and laterally,and is attached to the lunate and triquetral bones.

3. on the dorsal aspect of the joint:

1.dorsal radiocarpal ligament:-
~it is weaker than the palmar ligaments. It begins above from the posterior margin of the lower end of radius,runs downward and medially, and is attached below to the dorsal surfaces of the scaphoid,lunate,and triquetral bones.

2. the radial collateral ligaments:
~it extends from the tiup of the styloid process of the radius to the lateral side of the scaphoid bone.it is related to the radial artery.
*the ulnar collateral ligament:
~it extends from the tip of the styloid process of the ulna to the triquetral and pisiform bones.

Blood supply:
~anterior and posterior carpal arches.

Nerve supply:
~anterior and posterior interosseous nerves. (deep branch of the radial nerve)

Synovial membrane:
~it lines the fibrous capsule.

Vascular supply:
~ant interosseous A
~Ant and pos carpal branch of radial and ulnar arteries.
~palmar and dorsal metacarpal A
~Recurrent rami of the deep palmar arch.

innervation:
~ant & pos interosseous
~median, ulnar, and radial nerve

Wrist joint movements:

Wrist joints have mainly four movements while 2 associated movement

1. Wrist flexion
2. Wrist Extension
3. Wrist Radial Deviation
4. Wrist Ulnar Deviation
5. Pronation
6. Supination

Range of Movement:

                                             *flexion-85
                                             *extension-85
                                             *adduction or ulnar deviation-45
                                             *abduction or radial deviation-15
                                             *circumduction

Muscles around wrist joint:

Flexion:
~Flexor carpi radialis
~flexor carpi ulnaris
~palmaris longus
~the movement is assisted by long flexors of the fingers and thumb and abductor pollicis longus.

Extension:
~extensor carpi radialis longus
~extensor carpi radialis brevis
~extensor carpi ulnaris
~it is assisted by the extensors of the fingers and thumb.

Abuduction:
~Flexor carpi radialis
~extensor carpi radialis longus and extensor carpi radialis brevis
~abductor pollicis longus and abductor pollicis brevis

adduction:
~flexor carpi ulnaris
~extensor carpi ulnaris

cicumduction:
~the range of flexion is more than that of extension.similarly, the range of adduction is greater than abduction.

Injuries around Wrist

Wrist sprains are the most common injuries where ligaments are overstretched (Ligament tear).

*Scaphoid fracture:
~direct axial comression or hyperextension of wrist.
~diagnosed at pain or swelling at the base of the thumb.
~occurs commonly in young males and athelets.

*Lunate dislocation:
~due to fall from the hieght or and automobile collision.
~lunate bone gets dislocated.
~swelling,pain and limited motion of wrist and hand.

*Colles Fracture:

~it is a complete fracture of the radius bone of the forearm close to the wrist resulting in an upward (posterior) displacement of the radius and obvious deformity.

*Triquetrum fractures:

~there are carpal bone fractures generally occuring on the dorsal surface of the triquetrum. The triquetral may be fractured by means of impingement from the ulnar styloid, shear forces, or avulsion from strong ligamentous attachments.