Final answer:
The space between the cheeks or lips and the teeth is known as the oral vestibule, which acts as the entryway into the oral cavity.
Step-by-step explanation:
The space between the cheeks or lips and the teeth is called the oral vestibule. It serves as the entryway into the oral cavity, which extends inward from the gums and teeth to the fauces, the passage that connects the oral cavity to the oropharynx. While the fauces are interestsing in themselves, being the area which holds the tonsils and acting as a threshold to the throat, in this context of the locations within the mouth, the correct response is the vestibule. Cheeks and lips play a significant role, keeping food inside the mouth during the chewing process, thanks to the underlying muscles like the buccinator muscles in the cheeks and the orbicularis oris muscle in the lips.