What is the term for opening the mouth, which involves movement of the mandible?

What is the term for opening the mouth, which involves movement of the mandible?

• A. Elevation
• B. Depression
• C. Protraction
• D. Hyperextension

Answer: (B)

The term for opening the mouth is "depression" of the mandible. This refers to the downward movement of the lower jaw (mandible) away from the skull, allowing the mouth to open. During this action, the muscles responsible for this movement, mainly the digastric and mylohyoid muscles, contract and effectively lower the mandible.

In contrast, elevation would refer to the upward movement, which is the action taken when closing the mouth. Protraction involves moving the mandible forward, while hyperextension refers to moving a joint beyond its normal range of motion, which does not apply to the movement of opening the mouth. Thus, depression is the most accurate term for the action of opening the mouth due to the downward movement of the mandible.