Sartorius action?

• A. Abduction at hip
• B. Extension at knee; flexion at hip
• C. Medial rotation at knee
• D. Flexion at knee; flexion and lateral rotation at hip

Answer: (D)

Sartorius acts across two joints because it runs from the hip to the knee, so its actions happen at both joints. At the hip, it helps bend the thigh and, due to its diagonal path, can rotate the thigh outward (external rotation) and assist in abduction. At the knee, it helps bend the leg, and when the knee is flexed it can aid in rotating the tibia medially. The best choice reflects this two-joint action: knee flexion together with hip flexion and hip external rotation. Abduction is also a possible action of this muscle, but the combination shown here—knee flexion plus hip flexion and external rotation—most accurately captures its primary functional movements across both joints.