In the context of muscle actions, the primary function of the masseter muscle is to:

• A. Depress the mandible to open the jaw
• B. Elevate the mandible to close the jaw
• C. Protract the tongue during swallowing
• D. Retract the scapula toward the vertebral column

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the anatomy and function of the masseter muscle. The masseter is one of the main muscles involved in mastication (chewing). It is located on the side of the face and connects the zygomatic arch to the mandible.
2. Step 2: Recall the primary actions of the masseter muscle. Its main role is to elevate the mandible, which means it raises the lower jaw to close the mouth.
3. Step 3: Differentiate between elevation and depression of the mandible. Elevation refers to closing the jaw, while depression refers to opening the jaw. The masseter is responsible for elevation, not depression.
4. Step 4: Consider the other options given: protracting the tongue and retracting the scapula. These actions involve different muscles (tongue muscles and trapezius/levator scapulae respectively) and are unrelated to the masseter.
5. Step 5: Conclude that the primary function of the masseter muscle is to elevate the mandible to close the jaw, which aligns with its role in chewing.