- 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.
- 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.
Structures of the Forearm
- The forearm joints are composed of the proximal and distal radio-ulnar joints.
Movements of the Forearm
- Rotation of the radius around the ulnar allows for forearm supination and pronation.
Muscles of the Forearm Radio-ulnar Joint
|Pronator teres||Median nerve||Forearm pronation.|
|Pronator quadratus||Median nerve||Forearm pronation.|
|Biceps Brachii||Musculocutaneous nerve||Forearm supination (primary supinator of the forearm)|
|Supinator||Radial nerve||Forearm supination.|
Structures of the Wrist
- 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
Movements of the Wrist
- 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.
Muscles of the Wrist Joint
|Palmaris longus||Median nerve||Assists in flexion of wrist.|
|Flexor carpi radialis||Median nerve||Flexes and radially deviates wrist.|
|Flexor carpi ulnaris||Median nerve||Flexes and ulnarly deviates wrist.|
|Extensor carpi radialis longus||Radial nerve||Extends and radially deviates wrist.|
|Extensor carpi radialis brevis||Radial nerve||Extends and radially deviates wrist.|
|Extensor carpi ulnaris||Radial nerve||Extends and ulnarly deviates wrist.|
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