| | Conditions Treatments | Muscle Strain What muscle is pulled when the knee forced into extension hip already fully flexed? The rectus femoris muscle is pulled when the knee is forced into extension with the hip already fully flexed. Muscle Strain - Related Articles How to Stop Rectal Bleeding Does getting your finger pierced hurt? What is surgery? Why does symptoms of beta thalassemia appear at birth? What Is Considered a Low TSH Level? How to Prepare for Beginning Optifast Can someone get disease through making out or Sex?