The contraction of which muscle does NOT contribute to the depression of the mandible?

The temporalis muscle primarily functions to elevate the mandible, playing a pivotal role in jaw closure during chewing. It attaches to the temporal fossa and the coronoid process of the mandible, and when it contracts, it pulls the mandible upward rather than downward. Therefore, this muscle's contraction does not assist in the depression of the mandible.

In contrast, the lateral pterygoid muscle and the suprahyoid muscles are significant contributors to the depression of the mandible. The lateral pterygoid, in particular, assists in opening the mouth by pulling the head of the mandible forward and down. The suprahyoid muscles, located above the hyoid bone, also play a key role in mandible depression when they contract, especially during activities like swallowing and speaking.

The infrahyoid muscles, while not directly contributing to the depression of the mandible, assist with movements of the hyoid bone and may indirectly influence swallowing and related actions. However, their primary function is not associated with the movement of the mandible.

Understanding the specific functions of these muscles clarifies why the temporalis does not facilitate mandible depression, setting it apart from the other muscles mentioned.