Buccinator is a muscle of facial expression and as such is derived from the second pharyngeal arch and innervated by the buccal branch of the facial nerve.
It arises from the anterior margin of the pterygomandibular raphe (which also attaches to the superior pharyngeal constrictor) and inserts into the alveolar processes of both the maxilla and mandible. Buccinator lies deep to the ramus of the mandible and therefore also deep to masseter.
On contraction it pushes the cheeks against the teeth and gums to facilitate mastication, however, it is not considered a muscle of mastication. When the cheeks are puffed out contraction of buccinator results in forced expulsion of air through the lips – an action required to play wind instruments.
The parotid duct passes superficial to masseter and over its anterior border before piercing buccinator at the level of the 3rd molar.