Which muscle medially rotates the flexed knee?

Which muscle medially rotates the flexed knee?

• A. Gracilis
• B. Vastus Medialis
• C. Biceps Femoris
• D. Adductor Magnus

Answer: (A)

Medial rotation of the flexed knee is produced by muscles that cross the knee on its medial side and pull the tibia inward when the knee is bent. Gracilis crosses medially and attaches to the tibia, so when the knee is flexed, its contraction tends to rotate the tibia medially relative to the femur. This makes it the best choice among the options. The vastus medialis mainly extends the knee and isn’t a rotator of the tibia. The biceps femoris lies on the lateral side and powers lateral rotation of a flexed knee. The adductor magnus acts chiefly to adduct the thigh and assist thigh extension, not to rotate the knee.

Medial rotation of the flexed knee is produced by muscles that cross the knee on its medial side and pull the tibia inward when the knee is bent. Gracilis crosses medially and attaches to the tibia, so when the knee is flexed, its contraction tends to rotate the tibia medially relative to the femur. This makes it the best choice among the options.

The vastus medialis mainly extends the knee and isn’t a rotator of the tibia. The biceps femoris lies on the lateral side and powers lateral rotation of a flexed knee. The adductor magnus acts chiefly to adduct the thigh and assist thigh extension, not to rotate the knee.