The iliopsoas is formed by which two muscles?

• A. Psoas major and sartorius
• B. Iliacus and gluteus maximus
• C. Psoas major and iliacus
• D. Rectus femoris and vastus lateralis

Answer: (C)

The iliopsoas is a combined muscle formed by two deep hip flexors working together to pull the thigh forward. One comes from the lumbar spine (psoas major) and the other from the iliac fossa (iliacus); their fibers merge into a single tendon that attaches to the lesser trochanter of the femur. This arrangement makes the iliopsoas the primary hip flexor, especially when lifting the thigh with the trunk upright. The other muscles listed don’t make up this composite: sartorius is a long strap-like muscle that crosses the thigh and can aid hip flexion, gluteus maximus mainly extends the hip, and rectus femoris plus vastus lateralis are part of the quadriceps that extend the knee (and may assist hip flexion somewhat) but are not components of the iliopsoas.