The human face contains a complex network of muscles that allow for a wide range of expressions, communication, and biological actions. Specialized muscles in the cheeks and around the mouth are responsible for actions from speaking to creating a vacuum for drinking. A specific, deeper muscle is responsible for drawing the cheek inward. Understanding this muscle’s function reveals how the face manages necessary daily activities like eating and drinking.
The Buccinator Muscle and Its Location
The primary muscle responsible for sucking in your cheeks is the buccinator, a thin, quadrilateral muscle. It is a deep muscle that forms the lateral wall of the oral cavity. Its depth allows it to compress the cheek against the teeth.
The buccinator spans the space between the upper jaw (maxilla) and the lower jaw (mandible). Its fibers originate from the alveolar processes of both the maxilla and the mandible, near the molar teeth. It also originates from the pterygomandibular raphe, a connective tissue band separating it from the pharyngeal constrictor muscles.
The muscle fibers converge toward the front of the mouth, blending into the muscles of the lips. The buccinator inserts into the modiolus, a hub at the corner of the mouth, intermingling with the orbicularis oris muscle. Contraction pulls the angle of the mouth laterally and presses the cheek inward against the teeth.
The Role of Cheek Compression in Essential Functions
The buccinator’s action of compressing the cheek serves a fundamental purpose during mastication, or chewing. By pressing the cheek inward, the muscle ensures that food remains positioned on the molar teeth. This action prevents food particles from accumulating in the oral vestibule, the space between the gums and the cheek.
If the buccinator is weakened, food may pocket in this space, making chewing inefficient. The buccinator is sometimes referred to as an accessory muscle of mastication. It coordinates with the tongue, which pushes food inward, while the buccinator prevents it from escaping outward.
The muscle is activated early in life, playing a role in an infant’s ability to suckle and nurse. Drawing the cheek inward decreases the volume of the oral cavity, creating the necessary negative pressure, or vacuum, for sucking. This mechanism is also used for actions like whistling, blowing musical instruments, or forcefully expelling air.
Muscles That Partner with the Buccinator
While the buccinator compresses the cheek, it works in close coordination with a primary partner: the orbicularis oris. The orbicularis oris is the sphincter muscle encircling the mouth, and buccinator fibers directly blend with it at the corners of the mouth.
The orbicularis oris seals the lips, which is necessary to create a closed chamber in the oral cavity. This sealing action allows the buccinator to generate the vacuum required for sucking, since a leak at the lips would negate the negative pressure. Together, these muscles form a functional unit important for many orofacial functions, including speech and swallowing.
The buccinator is distinct from superficial muscles of facial expression, such as the zygomaticus muscles, which primarily form smiles. The buccinator lies beneath these muscles and focuses on compressing the cheek, not merely moving the skin. This layered arrangement allows for precise control over both functional tasks and visible expression.