Vastus Medialis
| Pronuncation | mee-dee-AL-iss |
| Derivation | The vast muscle on the medial side of the thigh. |
| Origin | Front surface on the upper end of the femur. The belly wraps around the medial side of the femur and attaches to a long line on the back. |
| Insertion | Patellar tendon. |
| Action | Straightens the leg at the knee. |