What is the primary action of the masseter muscle?

• A. Protracts the tongue
• B. Depresses the mandible (opens the jaw)
• C. Extends the neck
• D. Elevates the mandible (closes the jaw)

Answer: (D)

Verified step by step guidance

1. Step 1: Identify the anatomical location and function of the masseter muscle. The masseter is a muscle of mastication located on the side of the face, connecting the zygomatic arch to the mandible.
2. Step 2: Understand the primary movements of the mandible. The mandible can be elevated (closing the jaw), depressed (opening the jaw), protracted (moving forward), or retracted (moving backward).
3. Step 3: Recall that the masseter muscle's main role is to generate force for chewing by elevating the mandible, which closes the jaw.
4. Step 4: Differentiate the masseter's action from other muscles: muscles that depress the mandible open the jaw, while the masseter closes it; muscles that protract the tongue or extend the neck are unrelated to the masseter.
5. Step 5: Conclude that the primary action of the masseter muscle is to elevate the mandible, effectively closing the jaw during mastication.