Which muscle contracts when the tongue protrudes?

The correct answer is the genioglossus muscle, which plays a crucial role in the movement of the tongue, particularly during the action of protruding the tongue. This muscle is located primarily at the anterior part of the tongue and is responsible for its forward positioning.

When the genioglossus contracts, it pulls the tongue forward and downward, allowing it to protrude out of the mouth. This action is essential for various functions such as speaking, swallowing, and manipulating food. The genioglossus is one of the key muscles involved in controlling tongue movements, particularly those that require extension beyond the line of the teeth.

In contrast, the mylohyoid muscle is primarily involved in elevating the floor of the mouth and helping to form the floor of the oral cavity, while the digastric muscle assists in depressing the mandible rather than directly affecting tongue movement. The orbicularis oris muscle encircles the mouth and is involved in movements such as closing and puckering the lips, but does not contribute to the protrusion of the tongue. Hence, the genioglossus muscle is the specific muscle that directly facilitates the action of protruding the tongue.