The bi-articular hamstrings influence movement at which two joints?

The bi-articular hamstrings influence movement at which two joints?

• A. Hip and knee
• B. Knee and ankle
• C. Hip and ankle
• D. Shoulder and elbow

Answer: (A)

Bi-articular muscles cross two joints, so they can influence motion at both of those joints. The hamstrings cross the hip and the knee, attaching from the ischial tuberosity down to the tibia and fibula. Because they cross both joints, they contribute to hip extension (moving the thigh backward) and knee flexion (bending the knee). They do not cross the ankle or the upper body joints like the shoulder, so those aren’t affected. In running and sprinting, this dual action helps coordinate the leg’s movement across both joints during different phases of stride. Therefore, the two joints involved are the hip and the knee.

Bi-articular muscles cross two joints, so they can influence motion at both of those joints. The hamstrings cross the hip and the knee, attaching from the ischial tuberosity down to the tibia and fibula. Because they cross both joints, they contribute to hip extension (moving the thigh backward) and knee flexion (bending the knee). They do not cross the ankle or the upper body joints like the shoulder, so those aren’t affected. In running and sprinting, this dual action helps coordinate the leg’s movement across both joints during different phases of stride. Therefore, the two joints involved are the hip and the knee.