Which of the following is not considered an elevator muscle for masticatory movement?

The orbicularis oris muscle is not considered an elevator muscle for masticatory movement because its primary function is to control movements of the lips, including closing and protruding the lips, rather than facilitating the elevation of the mandible during chewing. This muscle plays a crucial role in speech and facial expressions but does not contribute to the masticatory process.

In contrast, the masseter, internal pterygoid, and the major part of the temporal muscle are all key muscles involved in elevating the mandible. The masseter muscle is known for its strength and is one of the main muscles that elevates the jaw, while the internal pterygoid assists in elevating the mandible and also plays a role in its lateral movements. The major part of the temporal muscle aids in the elevation of the mandible as well, especially during powerful closure. Therefore, recognizing the role of these specific muscles in masticatory movement is essential for understanding the mechanics of chewing.