The Buccinator Muscle is a slender, quadrilateral muscle that spans the space between the maxilla (upper jaw) and the mandible (lower jaw) on the side of the face. It forms the front of the cheek and the lateral wall of the oral cavity, playing an important role in chewing, sucking, and facial expressions.

Anatomy

Morphology and Connection Points

The Buccinator Muscle is a thin but powerful and broad facial muscle located deep in the cheek area. It originates from the outer surfaces of the alveolar processes of the maxilla and mandible; it is particularly prominent at the level of the three pairs of molars on both bones. It inserts into the prominent buccinator process behind the third molar on the mandible. The muscle also originates from the anterior border of the pterygomandibular raphe, forming an anatomical boundary between it and the superior pharyngeal constrictor muscle. The muscle fibers project toward the corner of the mouth, where the central fibers cross and fuse. The lower fibers connect with the orbicularis oris muscle of the upper lip, while the upper fibers connect with the orbicularis oris muscle of the lower lip, coordinating the complex movements of the lips. This unique structure allows the muscle to be effective in both chewing and facial expression. The buccinator muscle is a broad, flat, quadrangular-shaped muscle bundle. The muscle fibers cross bilaterally and attach to a strong modiolus fibrous structure at the corner of the mouth. The muscle spreads to the outer surfaces of the alveolar processes between the maxilla and mandible. Its insertion on the pterygomandibular raphe connects the muscle to the floor of the mouth and the pharyngeal muscles. The crossing of the fibers allows the cheeks to be pulled inward during contraction, preventing food from getting stuck between the teeth. Furthermore, its connection with the orbicularis oris plays a critical role in coordinating perioral movements.

Embryological Origin and Classification

The Buccinator Muscle develops embryologically from the mesoderm of the second pharyngeal arch and is classified as a muscle of facial expression. It is motorly innervated by the facial nerve (cranial nerve VII). Functionally, it possesses characteristics of both the muscles of mastication and the muscles of facial expression, thus lying at the intersection of the facial and masticatory systems. The muscle's anatomical connections allow it to play a flexible and versatile role in both oral movements and facial expressions.

Nerve Innervation and Vascular Supply

Motor innervation of the buccinator muscle is provided by the buccal branch of the facial nerve (cranial nerve VII). In contrast, sensory innervation of this region is provided by the buccal nerve, which arises from the mandibular branch of the trigeminal nerve (cranial nerve V). This differentiation necessitates separate assessment of motor and sensory functions in clinical practice. Vascular supply to the muscle is provided by the facial artery and the buccal branches of the maxillary artery; these vessels support the muscle's function by supplying oxygen and nutrients.

Function and Clinical Relationships

The Buccinator Muscle is a slender but powerful muscle that forms the cheek wall and plays a critical role in chewing, facial expression, and oral motor functions. The buccinator muscle originates from the alveolar processes of the maxilla and mandible and the pterygomandibular raphe. Its fibers join the orbicularis oris muscle to insert into the lateral border of the lips. Functionally, this muscle compresses the cheeks medially, preventing food from escaping into the buccal cavity and allowing the bolus to be retained between the teeth, improving chewing efficiency. This muscle function can be impaired, particularly in cases of unilateral tooth loss or facial paralysis, which can cause food to fill the cheek during chewing. The buccinator muscle is also activated during actions requiring intraoral pressure, such as blowing, whistling, and balloon inflation. Therefore, strengthening this muscle can be targeted in speech therapy sessions that require breath control. Working in synergy with the facial expression muscles, it contributes to the retraction of the corner of the mouth during smiling. In newborns, the buccinator plays a crucial role in feeding by creating negative pressure during the sucking reflex. The muscle is innervated by the buccal branches of the facial nerve, and lesions to this nerve can impair muscle function. Clinically, muscle damage due to trauma or surgery can lead to both functional and aesthetic problems. Furthermore, rarely, tumors originating from minor salivary glands can be encountered within the buccinator muscle.