What is the primary action of the tensor fasciae latae?

• A. Flex the hip
• B. Extend the stifle
• C. Tense the lateral femoral fascia
• D. Abduct the hip

Answer: (C)

The primary action of the tensor fasciae latae is to tense the lateral femoral fascia, which is accurately reflected in the correct choice. This muscle, located on the lateral side of the hip, plays a critical role in stabilizing the pelvis during activities such as walking and running by acting on the fascia lata—a deep fascia of the thigh that encases muscle compartments.

While the tensor fasciae latae does contribute to hip flexion and abduction, these actions are secondary to its primary function of tensing the fascia. By helping to tighten the fascia lata, it supports the iliotibial band, promoting stability and efficient movement of the lower limb. This stabilization is particularly vital when the leg is in motion or bearing weight.

The option related to extending the stifle is not applicable here, as the tensor fasciae latae does not have a direct role in knee extension. Its primary functions are specifically tied to the hip joint and the surrounding fascia, highlighting why tensing the lateral femoral fascia is considered the main action of this muscle.