What drives the pharyngeal phase?

What drives the pharyngeal phase?

• A. Swallowing center
• B. Cerebral cortex
• C. Spinal cord
• D. Brainstem reflex center

Answer: (A)

The pharyngeal phase is driven by the swallowing center in the brainstem (medulla). Sensory input from the oropharynx activates this center, which then rapidly coordinates the reflex sequence: pharyngeal constrictor muscles contract to push the bolus downward, the larynx elevates and the airway closes to protect it, and the upper esophageal sphincter relaxes to allow entry into the esophagus. This pattern is generated as a brainstem reflex via a central pattern generator, so the phase proceeds automatically after the swallow is triggered. The cerebral cortex can initiate swallowing, but the pharyngeal phase itself is controlled by this brainstem center, not by higher cortical input.

The pharyngeal phase is driven by the swallowing center in the brainstem (medulla). Sensory input from the oropharynx activates this center, which then rapidly coordinates the reflex sequence: pharyngeal constrictor muscles contract to push the bolus downward, the larynx elevates and the airway closes to protect it, and the upper esophageal sphincter relaxes to allow entry into the esophagus. This pattern is generated as a brainstem reflex via a central pattern generator, so the phase proceeds automatically after the swallow is triggered. The cerebral cortex can initiate swallowing, but the pharyngeal phase itself is controlled by this brainstem center, not by higher cortical input.