Which muscles are primarily responsible for the action of protrusion?

The primary muscles responsible for the action of protrusion of the mandible are the medial and lateral pterygoids, along with the masseter. The lateral pterygoid is particularly crucial for this movement, as it contracts to pull the head of the mandible forward, allowing the jaw to protrude. The medial pterygoid assists in this action by providing stability and helping in the forward movement as well. The masseter, while primarily known for elevation of the mandible, also plays a supportive role in protrusion when the jaw is moved forward.

In contrast, the other muscle groups listed do not play a primary role in this specific action. The masseter is known more for its role in closing the jaw, and while it contributes to various movements, it's not the main driver of protrusion. The anterior digastric and superior pterygoid serve different functions, primarily related to depression and stabilization rather than protrusion. The buccinator and orbicularis oris are facial muscles responsible for movements related to chewing and facial expressions, but they do not facilitate the protrusion of the mandible.