define buccinator
The thin, flat muscle forming the wall of the cheek. buccinator. the main muscle of the cheek, one of the 12 muscles of the mouth. It is pierced by the duct of the parotid gland opposite the second molar tooth. The buccinator, innervated by buccal branches of the facial nerve, compresses the cheek, acting as an important accessory muscle of mastication by holding food under the teeth. Buccinator.