Forearm (Radio-ulnar Joints) and Wrist Joint

Forearm:

• Rotation of the forearm allows for precise positioning of the hand in space.
• Forearm rotation also allows for various power activities of the hand such as turning a key.
• The muscles acting here can be denervated in various patterns of peripheral nerve injury such as that of the median nerve.
• Restoration, especially of pronation is critical for normal upper extremity function.

Wrist:

• Motion at the wrist joint serves to precisely position the hand for functional activity.
• Wrist extension allows for better power grip of the hand.
• The muscles acting here can be denervated in peripheral nerve injury.
• Restoration of wrist motion is secondary to that of shoulder, elbow and hand function.

• Bones:

• Radius
• Ulna

• The forearm joints are composed of the proximal and distal radio-ulnar joints.

• Rotation of the radius around the ulnar allows for forearm supination and pronation.

WRIST

Structures of the Wrist

• Bones

• Radius
• Ulna
• Carpal bones

• Joints (for the purposes of discussing peripheral nerve injury, the complex anatomy of the wrist joint is not as critical to delve into):

• Radiocarpal joint
• Mid-carpal joint

• Distal radioulnar joint

• Flexion and extension are movements about a coronal axis.

• Abduction (radial deviation) and adduction (ulnar deviation) are movements about a sagittal axis.
• Circumduction includes a combination of flexion, abduction, extension, and adduction of the radio-carpal and midcarpal joints.

Italics -- Note that there are additional muscles that assist or may assist but are not the primary action of wrist flexion and extension, abduction and adduction, and circumduction