Which muscle is responsible for both extending the hip and flexing the stifle?

• A. Gracilis
• B. Biceps femoris
• C. Semimembranosus
• D. Sartorius

Answer: (B)

The biceps femoris muscle is a part of the hamstring group, and it plays a crucial role in both extending the hip and flexing the stifle (knee) joint. This muscle is located at the back of the thigh and is made up of two heads: the long head and the short head.

The long head of the biceps femoris contributes to hip extension by pulling the femur back, aiding movements such as running or jumping. At the same time, this muscle assists in flexing the stifle by contracting and drawing the tibia closer to the femur, making it important for activities that require bending the knee.

In contrast, other muscles listed in the options have more specific or singular functions. For example, the gracilis predominantly aids in adducting the thigh and does not significantly contribute to flexing the stifle or extending the hip in the same way. The semimembranosus is primarily focused on extending the hip and flexing the stifle as well, but the question seeks the muscle that performs both functions simultaneously. The sartorius primarily flexes the hip and knee, but it does not extend the hip. Therefore, the biceps femoris is the most accurate choice for performing both actions