Bucinator

At a glance

English

Bucinator

Latin (TA2)

Bucinator

System

Muscle

Region

Head

Side

Paired, left and right

Arises from

The mandible

About the bucinator

The buccinator is a thin, four-sided sheet that makes up the deep, muscular layer of the cheek. It spans the gap between upper and lower jaw bones, with the mucous membrane of the mouth on its inner face and the buccal fat pad, the facial vessels and the other facial muscles over its outer face. Because it forms the side wall of the mouth cavity, it is the muscle you feel tighten when you press the tongue into the cheek.

It has a long, horseshoe-shaped origin at the back. Above and below, its fibres spring from the buccal faces of both alveolar processes opposite the three molar teeth; on the mandible the attachment extends onto the buccinator crest behind the last molar. Behind, it springs from the pterygomandibular raphe, a fibrous band it shares with the superior constrictor of the pharynx, so the cheek and the pharyngeal wall form one continuous muscular tube. The fibres run forward to the mouth's corner. There the middle fibres cross, those from below passing into the upper lip and those from above into the lower lip, while the highest and lowest fibres continue straight into their own lip. In this way it blends with orbicularis oris.

Its main work is to hold the cheek flat against the teeth. During chewing this keeps food from collecting in the vestibule and pushes it back between the molars, so the buccinator is a partner of the muscles of mastication even though it does not move the jaw. It also draws the mouth's corner backwards, helps in smiling and whistling, expels air when the cheeks are puffed, as in playing a wind instrument, and in infants helps with suckling.

Several structures pass through it: the parotid duct pierces it opposite the upper second molar to open into the mouth, and small molar glands and branches of the buccal nerve also cross it. It is a muscle of facial expression, so its motor supply is the facial nerve; the buccal nerve from the mandibular division of the trigeminal is sensory only and supplies the overlying skin and the lining of the cheek. Weakness after facial palsy lets food pocket in the cheek on the affected side.

Attachments, action and supply

Origin

Buccal faces of the maxillary and mandibular alveolar processes opposite the molar teeth, the buccinator crest of the mandible, and the pterygomandibular raphe.

Insertion

Corner of the mouth (modiolus), blending with orbicularis oris in the upper and lower lips.

Action

Presses the cheek against the teeth, keeps food between the molars during chewing, pulls the mouth's corner back and expels air from the puffed cheeks.

Nerve supply

Facial nerve (VII), through its buccal branches.

Blood supply

Buccal artery from the maxillary artery, with branches of the facial artery.