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.
FOREARM
Structures of the Forearm
- Bones:
- 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
Muscle Name |
Innervation |
Action |
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. |
WRIST
Structures of the Wrist
- 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
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
Muscle Name |
Innervation |
Action |
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 |
|