Deglutition (swallowing) is a complex, coordinated process that moves food from the mouth to the stomach. It occurs in three distinct phases:
1. Oral Phase (Voluntary)
- The tongue presses food against the hard palate, forming a bolus.
- Saliva moistens the bolus and begins carbohydrate digestion.
2. Pharyngeal Phase (Involuntary)
- The bolus reaches the oropharynx, triggering the swallow reflex.
- The soft palate elevates to seal the nasal cavity.
- The epiglottis folds down to cover the trachea, preventing aspiration.
- Pharyngeal muscles contract, propelling the bolus into the esophagus.
3. Esophageal Phase (Involuntary)
- Peristaltic waves push the bolus down the esophagus.
- The lower esophageal sphincter relaxes to allow entry into the stomach.
The entire process takes seconds. Disorders (dysphagia) can arise from neurological, muscular, or structural issues affecting any phase.
