Does the mandible use a third and second class lever?

Yes, the mandible uses both a third and second class lever.

The mandible is a bone that forms the lower jaw. It is connected to the skull at the temporomandibular joint (TMJ). When you open your mouth, the mandible rotates around the TMJ. The masseter muscle is the main muscle that opens the mouth. It inserts on the mandible and pulls it downward. The temporalis muscle also assists in opening the mouth. It inserts on the mandible and pulls it upward and forward.

The mandible acts as a third class lever when you open your mouth. The TMJ is the fulcrum, the masseter muscle is the effort force, and the resistance force is the weight of the mandible. The effort force is greater than the resistance force, so the mandible can be opened easily.

The mandible also acts as a second class lever when you close your mouth. The TMJ is still the fulcrum, but the resistance force is now the bite force. The bite force is greater than the effort force, so the mandible can be closed forcefully.

The mandible is a complex bone that uses a variety of levers to perform its functions. The third and second class levers allow the mandible to open and close smoothly and powerfully.