Final answer:
The suprahyoids assist the lateral pterygoids in opening the mouth and cooperate with the masseter muscles when elevating the mandible for chewing.
Step-by-step explanation:
The suprahyoid muscles are a group of muscles that assist with swallowing and speaking by raising the hyoid bone, which also lifts the larynx, allowing the epiglottis to cover the glottis during deglutition. These muscles also play a role in mouth opening by depressing the mandible. Specifically, the suprahyoids assist the lateral pterygoids with mouth opening and work with the masseter muscles when the mandible is being elevated during chewing.