Which of the following muscles is not a part of the quadriceps group?

• A. Vastus lateralis
• B. Vastus medialis
• C. Vastus intermedius
• D. Iliopsoas

Answer: (D)

The iliopsoas is not part of the quadriceps group, making it the correct answer. The quadriceps group consists of four muscles that are primarily responsible for extending the knee: vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris. Each of these muscles plays a key role in movement and stability of the knee joint.

The iliopsoas, on the other hand, is a muscle group that includes the psoas major and iliacus. Its primary function is to flex the hip joint and assist with movements such as lifting the thigh or bringing the knee towards the torso. Therefore, while the iliopsoas is a crucial muscle group for hip movements, it does not contribute to the action of the quadriceps, which is focused solely on extending the knee.