<prompt> All of the following structures pierce the buccinator muscle exceptParotid ductMolar glands of the checkBuccal branch of facial nerveBuccal branch of the mandibular nerve  <response>: Buccinator, the muscle of the cheek. Pierced by Parotid duct Buccal branch of mandibular nerve actions: Flattens cheek against gums and teeth prevents accumulation of food in the vestibule. This is the whistling muscle. Ref BDC volume 3;sixth edition pg 66 