All the following structures are pierced by Stenson's duct except
The parotid duct pierces buccal pad of fat, buccopharyngeal fascia, buccinator muscle and the mucous membrane to open into the vestibule of mouth opposite the crown of the upper second molar tooth.Reference: Chourasia; 6th edition; 61 pages
Buccopharyngeal Fascia
Pharyngobasilar Fascia
Buccal pad of fat
Buccinator
Head and neck