Overview
This lecture covers the anatomy of the pronator quadratus muscle, focusing on its location, origin, insertion, and primary action in the forearm.
Location and Structure
- The pronator quadratus lies deep in the anterior (front) compartment of the forearm.
- It connects the ulna and radius near the wrist.
- The muscle fibers run parallel between these two bones.
- It is not visible or palpable due to being covered by other forearm muscles.
Origin and Insertion
- The origin is on the distal (toward the wrist) and anterior surface of the ulna.
- The insertion is on the distal and anterior surface of the radius.
Action
- The pronator quadratus muscle pronates the forearm, turning the palm downward.
- Pronation occurs as the radius rotates over the ulna, changing the palm's orientation from up (supination) to down (pronation).
Key Terms & Definitions
- Origin — The point where a muscle attaches proximally; for pronator quadratus, it is the distal anterior ulna.
- Insertion — The distal attachment point; for pronator quadratus, it is the distal anterior radius.
- Pronation — Rotation of the forearm so that the palm faces downward.
- Supination — Rotation of the forearm so the palm faces upward.
- Anterior — Refers to the front surface of the body or limb.
- Distal — Farther from the body’s center or point of attachment.
Action Items / Next Steps
- Review the anatomy of the forearm muscles, focusing on the deep layer.
- Practice identifying the origin and insertion points on diagrams or models.
- Ensure understanding of pronation vs. supination movements.