## **Core Concept**
The question tests knowledge of hip anatomy, specifically muscles attached to the femur's greater trochanter. The greater trochanter is a large, irregular, quadrilateral eminence at the junction of the neck with the upper end of the body of the femur. It serves as an attachment point for several muscles.

## **Why the Correct Answer is Right**
The correct answer, **gluteus medius** and **gluteus minimus**, are muscles of the buttock that play a crucial role in hip abduction and stabilization. These muscles attach to the lateral surface of the greater trochanter. The **gluteus medius** muscle originates from the lateral surface of the ilium and inserts into the lateral surface of the greater trochanter of the femur. The **gluteus minimus** muscle lies deep to the gluteus medius and also inserts into the greater trochanter. Both muscles are innervated by the superior gluteal nerve and are essential for maintaining the pelvis level during gait.

## **Why Each Wrong Option is Incorrect**
- **Option A:** The **piriformis muscle** originates from the anterior (pelvic) surface of the sacrum and inserts into the top of the greater trochanter, not the lateral surface.
- **Option B:** The **gluteus maximus** primarily inserts into the iliotibial tract and the gluteal tuberosity of the femur, not the greater trochanter.
- **Option D:** The **iliopsoas** muscle inserts into the lesser trochanter of the femur.

## **Clinical Pearl / High-Yield Fact**
A key clinical correlation is the Trendelenburg gait, which can result from weakness of the **gluteus medius** and **gluteus minimus**. This gait is characterized by a dip of the pelvis on the contralateral side during single-leg stance, indicating hip abductor weakness.

## **Correct Answer:** C. Gluteus medius and minimus.