Which of the following muscles is involved in inversion at the ankle joint?

• A. Fibularis longus
• B. Tibialis anterior
• C. Extensor digitorum longus
• D. Gastrocnemius

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the movement of inversion at the ankle joint. Inversion refers to the movement where the sole of the foot turns inward, toward the midline of the body.
2. Step 2: Review the primary muscles responsible for inversion. The tibialis anterior and tibialis posterior are the key muscles involved in this movement.
3. Step 3: Analyze the function of each muscle listed in the options: - Fibularis longus: This muscle is involved in eversion (turning the sole outward) and plantar flexion, not inversion. - Tibialis anterior: This muscle is responsible for dorsiflexion and inversion of the foot. - Extensor digitorum longus: This muscle primarily extends the toes and assists in dorsiflexion, but it does not contribute significantly to inversion. - Gastrocnemius: This muscle is involved in plantar flexion of the foot and flexion of the knee, not inversion.
4. Step 4: Identify the correct muscle based on its function. Since the tibialis anterior is directly involved in inversion at the ankle joint, it is the correct answer.
5. Step 5: Confirm your understanding by reviewing the anatomy of the tibialis anterior. It originates from the lateral surface of the tibia and inserts on the medial cuneiform and first metatarsal, allowing it to pull the foot inward during inversion.