**Question:** Pes anserinus includes following three muscles EXCEPT

A. Sartorius
B. Semitendinosus
C. Semimembranosus
D. Quadriceps femoris

**Core Concept:** Pes anserinus is a group of three muscles in the lower leg that insert into the medial condyle of the tibia. These muscles are involved in flexion, adduction, and internal rotation of the knee joint.

**Why the Correct Answer is Right:** The correct answer, D. Quadriceps femoris, is incorrect because it refers to a group of four muscles that primarily extend the knee, not flex it, adduct it, or involve in internal rotation. The Quadriceps femoris is composed of:

1. **Rectus femoris:** Lengthens the leg, flexes the knee, and adducts the thigh
2. **Vastus lateralis, medialis, and intermedius:** Extend the knee and abduct the thigh

The other options are correct:

**Why Option A (Sartorius):** The Sartorius is a long, thin muscle that primarily flexes the knee and internally rotates the thigh, not the knee joint. It originates from the pubic symphysis and inserts into the medial condyle of the tibia.

**Why Option B (Semitendinosus):** The Semitendinosus is a muscle that flexes the knee and internally rotates the tibia, not the knee joint. It originates from the posterior aspect of the hamstring group and inserts into the medial condyle of the tibia.

**Why Option C (Semimembranosus):** The Semimembranosus is another muscle that flexes the knee and internally rotates the tibia, not the knee joint. It originates from the posterior aspect of the hamstring group and inserts into the medial condyle of the tibia.

**Why Option D (Quadriceps femoris):** This option is incorrect as mentioned above, as Quadriceps femoris is responsible for knee extension, not flexion or internal rotation.

**Why Option E (M. Femoralis longus):** M. Femoralis longus is not a relevant option as it is a muscle of the thigh, extending the knee and abducting the thigh, which does not relate to the knee joint movements. It originates from the anterior surface of the lesser trochanter of the femur and inserts into the head of the fibula, not the knee joint.

**Core Concept:** Understanding the anatomy and functions of different muscles in the lower limb is essential for understanding knee joint movements and clinical evaluations.

**Why Option F (M. Biceps femoris):** M. Biceps femoris is responsible for knee flexion and supination of the forearm, not movements of the knee joint. It originates from the lateral head of the femur and inserts into the tuberosity of the radius.

**Why Option G (