Some oral and pharyngeal structures including the floor of mouth and lateral pharyngeal walls are not well delineated on fluoroscopy . However a number of osseous and soft tissue components are readily visible and may be reliably assessed with the VFSS (Fig. 4.3). The mandible and maxilla with their associated teeth surround the visible fluoroscopic oral cavity. The oral tongue is best visualized when a radiopaque bolus is in the mouth or is coated with contrast. The soft palate and its most inferior component, the uvula, are generally identifiable as is the tongue base. Posterior to the tongue base, the epiglottis is visible in the air-filled common aerodigestive tract and forms the posterior limit of the vallecula. The posterior portion of the pharyngeal constrictors apposes the cervical spine and easily is assessed.

Normal anatomic findings include an intact mandibular arch of adequate height with a full complement of healthy teeth. The oral tongue should fill the oral vestibule and the tongue base should be visible beyond the angle of the mandible though not obscuring the vallecula. A perfectly normal epiglottis is thin having a width less than 8 mm or 33 % of the width of C4 (Fig. 4.4). It also follows a slight cranial curvature. The posterior pharyngeal wall should have a near uniform thickness measuring approximately 0.30–0.40 cm between C2 and C3 (Fig. 4.4). Findings outside of these standards may be considered normal and include altered or replaced dentition, mandibular atrophy in the elderly, vallecular filling by the lingual tonsil, retroflexion of the epiglottis, and mild pharyngeal wall thickening particularly if over-lying a prior surgical site or spinal fusion plate. Abnormal fluoroscopic oral and pharyngeal anatomy will be reviewed in Chap. 9.