Name a hamstring muscle that extends the hip and flexes the knee.

• A. Biceps femoris long head
• B. Gracilis
• C. Sartorius
• D. Gastrocnemius

Answer: (A)

The important idea here is that some muscles cross two joints and can produce actions at both when they contract. The long head of the biceps femoris is a two-joint hamstring originating on the ischial tuberosity and crossing both the hip and the knee. Because of this arrangement, its contraction extends the hip (pulling the thigh backward) and also flexes the knee (bending the leg). That combination fits the action described.

The other options don’t match both actions. Gracilis is an adductor that can contribute to knee flexion but doesn’t extend the hip. Sartorius crosses the thigh obliquely and mainly acts to flex the hip and knee, not extend the hip. Gastrocnemius crosses the knee and ankle but primarily acts at the ankle (plantarflexion) and only assists knee flexion, not hip extension. So the long head of the biceps femoris is the one that both extends the hip and flexes the knee.