The human face contains a complex network of muscles controlling emotional expressions and mechanical processes like eating and speaking. While many muscles work in coordinated groups, some perform a single, highly specific action fundamental to daily life. The ability to pull the cheeks inward, for example, is a dedicated function performed by a deep-seated muscle. This action ensures the structures of the mouth function correctly during various activities.
The Buccinator: The Primary Muscle for Inward Cheek Movement
The buccinator is the specific muscle responsible for the inward pull and compression of the cheeks. It is a broad, thin, quadrilateral muscle forming the substance of the cheek wall. Its primary action involves pressing the cheek against the teeth and gums, pulling the soft tissue inward toward the oral cavity. This compression is fundamental for creating the negative pressure needed for actions like sucking or holding air to whistle.
The name “buccinator” is derived from the Latin word buccina, referring to a trumpet or horn. Due to its role in forcefully expelling air, the muscle is sometimes called the “trumpeter’s muscle.” Unlike many facial muscles focused on expression, the buccinator’s main role is deeply functional and mechanical. Its ability to flatten the cheek distinguishes it from superficial muscles, such as the zygomaticus muscles, which lift the corners of the mouth for smiling.
Anatomical Placement and Structure
The buccinator is positioned deep within the face, situated between the upper jaw (maxilla) and the lower jaw (mandible). It lies beneath superficial structures like the masseter muscle and the buccal fat pad, forming the lateral boundary of the oral cavity. Its fibers have three main points of origin, including the outer surfaces of the alveolar processes of the maxilla and mandible.
A significant portion of the muscle also originates from the pterygomandibular raphe, a fibrous band connecting the buccinator to the superior constrictor muscle of the pharynx. The fibers run forward horizontally, converging toward the corner of the mouth, where they blend into the orbicularis oris muscle. This broad attachment allows the buccinator to exert comprehensive pressure across the cheek area. Motor control is supplied by the buccal branch of the facial nerve (Cranial Nerve VII), classifying it as a muscle of facial expression.
Essential Roles in Everyday Function
The buccinator’s inward-pulling action is most constantly employed during mastication. By compressing the cheek against the teeth, the muscle keeps the food bolus centralized on the grinding surfaces of the molars. This prevents food from escaping into the oral vestibule, the space between the cheek and the gums. This action eliminates the need to constantly use the tongue to retrieve trapped particles.
The buccinator is also a primary component of the sucking reflex, making it one of the first muscles an infant learns to control. The compression of the cheeks helps an infant effectively create and maintain the necessary suction for suckling. The buccinator also plays a role in speech articulation by helping control the shape of the oral cavity for clear pronunciation. Maintaining cheek tension also prevents the inner lining of the cheek from being accidentally bitten while chewing.