Final answer:
The muscle that pulls the corners of the mouth downward into a frown is the depressor anguli oris, which is not listed in the provided options. The muscles mentioned, such as the masseter and corrugator supercilii, serve different functions in facial expressions and movements.
Step-by-step explanation:
The muscle responsible for pulling the corners of the mouth inferiorly into a frown position is known as the depressor anguli oris (not specifically mentioned in the provided information but is the correct answer based on human anatomy). However, from the options given, the correct answer is not listed since these muscles serve different functions:
- The occipitofrontalis muscle elevates the eyebrows and wrinkles the forehead.
- The corrugator supercilii draws the eyebrows medially and downward, producing the vertical wrinkles of the forehead.
- The sternocleidomastoid assists in various head movements.
- The masseter is a primary muscle for chewing and elevating the mandible.
The information provided discusses the buccinator muscle, which is mostly involved in compressing the cheek, contributing to whistling, blowing, sucking, and chewing activities. It also mentions the corrugator supercilii, which is primarily responsible for moving the eyebrows, particularly in expressions such as frowning or surprise. Muscles like the masseter play a significant role in the chewing process, and other facial muscles contribute to various expressions by moving the skin.