WRIST JOINT

Wrist Joint

Definition

Wrist joint is a complex hinge joint that connects the distal ends of radius and ulna bones of forearm with the proximal row of carpal bones of the hand.

Structure

• Distal radioulnar joint: Connects distal ends of radius and ulna bones.
• Radiocarpal joint: Connects distal end of radius bone with proximal row of carpal bones (scaphoid, lunate, triquetrum).
• Ulnocarpal joint: Connects distal end of ulna bone with proximal row of carpal bones (pisiform, triquetrum).
• Midcarpal joint: Connects proximal and distal rows of carpal bones (scaphoid, lunate, triquetrum with trapezium, trapezoid, capitate, hamate).

Articular Surfaces

• Distal end of radius: Concave surface for articulation with scaphoid bone.
• Distal end of ulna: Convex surface for articulation with triquetrum bone.
• Proximal row of carpal bones: Concave surface for articulation with distal ends of radius and ulna bones.

Ligaments

• Radiocarpal ligaments: Strong ligaments that connect radius bone with proximal row of carpal bones.
• Ulnocarpal ligaments: Weak ligaments that connect ulna bone with proximal row of carpal bones.
• Interosseous ligaments: Connect carpal bones to each other.

Blood Supply

• Radial artery: Supplies blood to radiocarpal joint.
• Ulnar artery: Supplies blood to ulnocarpal joint.
• Palmar carpal artery: Supplies blood to midcarpal joint.

Nerve Supply

• Radial nerve: Supplies sensation to dorsal aspect of wrist.
• Ulnar nerve: Supplies sensation to palmar aspect of wrist.

Function

• Flexion: Performed by flexor carpi radialis, flexor carpi ulnaris, and flexor digitorum profundus muscles.
• Extension: Performed by extensor carpi radialis brevis, extensor carpi ulnaris, and extensor digitorum muscles.

Movement

• Flexion: Movement of wrist towards palmar surface.
• Extension: Movement of wrist towards dorsal surface.

Stability

• Radial collateral ligament: Provides stability to radiocarpal joint.
• Ulnar collateral ligament: Provides stability to ulnocarpal joint.

Clinical Significance

• Wrist sprains: Injuries to ligaments surrounding wrist joint.
• Wrist fractures: Fractures of bones surrounding wrist joint.

Flowchart:

Radiocarpal Joint → Ulnocarpal Joint → Midcarpal Joint