All are abductors of thigh, EXCEPT?
**Core Concept**
The question is testing the knowledge of muscle anatomy and their functions in the thigh. The main concept here is the identification of muscles that have a primary action of abduction, which is the movement of the thigh away from the midline of the body.
**Why the Correct Answer is Right**
Abduction of the thigh is primarily performed by the gluteus medius and gluteus minimus muscles, which are innervated by the superior gluteal nerve. These muscles work together to stabilize the hip joint and facilitate abduction. The tensor fasciae latae muscle, also an abductor, is innervated by the superior gluteal nerve, but it has a secondary action of flexion and internal rotation. The primary abductors work in conjunction with the other hip muscles to maintain normal gait and prevent hip subluxation.
**Why Each Wrong Option is Incorrect**
**Option A:** The tensor fasciae latae muscle is indeed an abductor of the thigh, but it has secondary actions as well. It is not the primary abductor, but it is still involved in abduction.
**Option B:** The gluteus maximus muscle is the primary extensor of the hip joint, but it also assists in abduction, particularly in the terminal phase of abduction. It is not the primary abductor, but it plays a role in this movement.
**Option C:** The iliopsoas muscle is primarily an extensor and flexor of the hip joint. It has a secondary action of internal rotation and is not a primary abductor of the thigh.
**Clinical Pearl / High-Yield Fact**
In patients with hip disorders, such as hip dysplasia or hip arthritis, the gluteus medius and minimus muscles may be weakened, leading to abnormal gait patterns and increased risk of falls. It is essential to assess and rehabilitate these muscles in patients with hip problems to improve functional outcomes.
**Correct Answer: D.** Iliopsoas muscle