Which muscle is responsible for knee flexion, hip adduction, and medial rotation?

• A. Gracilis
• B. Gastrocnemius
• C. Soleus
• D. Tibialis Anterior

Answer: (A)

Gracilis best fits this combination because it crosses both the hip and knee joints, allowing it to contribute to hip adduction and knee flexion, and it can medially rotate the thigh when the hip is flexed. Its pull from the pubic ramus to the medial tibia enables bringing the thigh inward (adduction), assisting in bending the knee (knee flexion), and helping rotate the leg toward the midline when the knee is in a flexed position.

The other muscles don’t match all three actions together. The gastrocnemius can help bend the knee but is mainly involved in plantarflexing the ankle and doesn’t adduct the hip or medially rotate the thigh. The soleus is also a plantarflexor with no role in knee flexion or hip adduction. The tibialis anterior acts on the ankle, producing dorsiflexion and foot inversion, but it has no hip adduction or knee flexion function.