Which muscle or tendon is responsible for internal snapping of the hip?

The iliopsoas muscle is primarily responsible for internal snapping of the hip. This muscle group consists of two muscles: the iliacus and the psoas major. It originates from the lumbar spine and iliac fossa and inserts into the lesser trochanter of the femur. The biomechanics of the hip joint and the function of the iliopsoas can lead to snapping sensations, particularly during activities that involve hip flexion.

When the hip flexes, the iliopsoas can rub over the bony structures of the hip, which can produce the characteristic internal snap. This snapping is often associated with certain movements, especially in activities like running or kicking, where flexion and rotation occur simultaneously. Other muscles listed, such as the tensor fasciae latae, pectineus, and gluteus maximus, are not typically involved in this specific snapping mechanism, as they do not have the same anatomical relationships to the hip joint as the iliopsoas. Therefore, the iliopsoas plays the key role in causing this phenomenon.