Which of the following is a primary muscle of mastication?

• A. Masseter
• B. Scalene
• C. Sternocleidomastoid
• D. Trapezius

Answer: (A)

Chewing relies on muscles that close and move the jaw. One of the primary jaw-closers is the masseter, a thick muscle on the cheek that elevates the mandible to bite down. It’s essential for generating bite force and works with other main movers like the temporalis and medial pterygoid.

The neck and shoulder muscles—scalene muscles, sternocleidomastoid, and trapezius—aren’t primary movers of the jaw. They mainly stabilize or move the head and neck, not perform the chewing motions.

So, the masseter is the correct choice because it directly drives jaw elevation, a defining action in mastication.