What is the function of the tensor fasciae latae?

• A. Hip extension
• B. Hip abduction and flexion; tightens the iliotibial band to stabilize the knee
• C. Knee flexion
• D. Plantarflexion

Answer: (B)

The main concept here is how the tensor fasciae latae functions to move and stabilize the leg. The TFL primarily abducts and flexes the hip. Its tendon also tightens the iliotibial band as it contracts, and that IT band runs down the outside of the thigh to insert near the knee. When the IT band is taut, it helps stabilize the knee during activities like standing and walking by guiding and supporting the kneecap and tibia on the femur. So the combination of hip abduction and flexion, with the added effect of pulling on the IT band to stabilize the knee, is what defines the TFL’s role.

That’s why other options don’t fit: extending the hip is mainly the job of the gluteus maximus and other hip extensors; knee flexion is produced by the hamstrings; plantarflexion is an ankle action. The TFL’s primary contribution is at the hip (abduction and flexion) and in tensioning the IT band to help knee stability.