Bucinator

The buccinator is a thin, quadrilateral muscle forming the muscular wall of the cheek. Although classified among the muscles of facial expression, it also acts as an accessory muscle of mastication, maintaining food between the occlusal surfaces of the teeth during chewing. It also possesses a functional role in blowing and whistling.

Anatomical Description

1. Origin

• Alveolar processes of the maxilla and mandible opposite the molar teeth.

• Pterygomandibular raphe, a fibrous band between the pterygoid hamulus and the posterior end of the mylohyoid line of the mandible.

2. Course and Structure

• The buccinator fibres pass anteriorly from their origins to converge toward the modiolus at the angle of the mouth. At this point, the central (pterygomandibular) fibres decussate — crossing so that the upper fibres pass to the lower part of the orbicularis oris, while the lower fibres ascend to the upper part of the same muscle. The uppermost fibres, derived from the maxilla, and the lowermost fibres, from the mandible, do not cross; instead, they continue directly forward to blend with the corresponding orbicularis oris fibres of the upper and lower lips, respectively.

• Along their course, some deep fibres of the buccinator insert directly into the submucosa of the cheek, contributing to its tone, firmness, and elasticity.

3. Insertion

• Into the angle of the mouth, blending with the orbicularis oris muscle; some deep fibres also insert into the submucosa of the cheek.

4. Relations

• Posteriorly: Lies in the same plane as the superior pharyngeal constrictor, separated by the pterygomandibular raphe.

• Superficially: Covered by the buccopharyngeal fascia, buccal fat pad, facial vessels, and buccal branch of the facial nerve.

• Deeply: Related to the buccal glands and mucosa of the cheek.

• Parotid duct (Stensen’s duct): Pierces the buccinator opposite the second maxillary molar tooth to open into the oral cavity.

Vascular Supply

• Facial artery (buccal branches).

• Buccal branch of the maxillary artery.

Innervation

• Motor: Buccal branch of the facial nerve (cranial nerve VII).

• Sensory: Buccal branch of the mandibular nerve (CN V₃) supplies overlying mucosa and skin.

Actions

• Compresses the cheek against the teeth and gums during mastication, preventing food from collecting in the vestibule.

• Assists blowing, sucking, and whistling by compressing the oral cavity and expelling air.

• Retracts the angle of the mouth and aids speech articulation.

• Acts synergistically with the orbicularis oris and tongue muscles during chewing and swallowing.

Clinical Relevance

• Facial nerve palsy → flaccid paralysis of buccinator causes food trapping between cheek and teeth.

• During dental anaesthesia, the pterygomandibular raphe serves as a key landmark for inferior alveolar nerve blocks.