Which structures are primarily involved in shaping and containment of the bolus during the oral preparatory phase of swallowing?

• A. Lips, teeth, tongue, and mandible shaping and containment of the bolus
• B. Soft palate elevation and pharyngeal constrictors
• C. Hyoid and laryngeal elevation
• D. UES opening and esophageal peristalsis guiding the bolus to the stomach

Answer: (A)

In the oral preparatory phase, shaping and containment of the bolus inside the mouth are achieved mainly by the lips, teeth, tongue, and mandible. The lips seal to prevent leakage, the teeth and mandible perform the grinding, and the tongue positions and compresses the food against the palate to form a cohesive bolus ready for propulsion. The soft palate and pharyngeal muscles play roles later in the swallow, primarily for airway protection and directing the bolus into the pharynx, while hyoid and laryngeal elevation and esophageal movements occur in subsequent phases. So, the mouth-based structures are the ones most involved in this initial shaping and containment.