Which muscle is responsible for closing the jaw?

The muscle responsible for closing the jaw is the masseter. This powerful muscle plays a crucial role in the process of mastication, or chewing. It originates from the zygomatic arch and inserts into the mandible, allowing it to elevate the jaw. When the masseter contracts, it pulls the lower jaw upwards, effectively closing the mouth.

While the pterygoid muscles (particularly the medial pterygoid) also assist in closing the jaw by elevating the mandible, and the temporalis muscle supports this action by retracting the jaw, the primary muscle for this function is the masseter. The buccinator, on the other hand, is more involved in manipulating food while chewing and keeping food within the oral cavity rather than directly closing the jaw.