Pronator quadratus
Arms
Deep muscle — it lies under other muscles. X-ray makes the muscles over it see-through.
- Origin
- Lower quarter of the front of the ulna
- Insertion
- Lower quarter of the front of the radius
- Action
- Pronates the forearm (turns the palm down)
- Nerve supply
- Anterior interosseous nerve (median nerve, C7–C8)
A flat, square muscle across the front of the forearm just above the wrist. It is the main muscle that turns the palm down, helped by the pronator teres.
Pronator quadratus anatomy page →