THE FOUR STAGES OF SWALLOW
The following information on the normal swallow is sourced from Groher & Crary (2010).
1. Oral Preparatory Stage (voluntary control), in which the food is chewed (in combination of lips, tongue, mandible, palate and cheeks, mixed with saliva, and formed into a bolus.
  • This stage ensures that food is presented into the correct position and consistency so the following stages of swallowing can take place safely and appropriately.

2. Oral Stage (voluntary control), in which the food is moved back through the mouth with a front-to-back squeezing action, performed primarily by the tongue.
  • The oral stage of swallowing in healthy individuals is generally completed in approximately one second.

3. Pharyngeal Stage (involuntary control), which begins with the reflexive pharyngeal swallowing response.
  • Velopharyngeal closure prevents reflux.
  • Larynx closure in precise sequence prevents aspiration; true vocal folds adduct and ensure no bolus reaches the trachea, retroversion of the epiglottis directs the bolus to the pyriform sinuses.
  • Pharyngeal constrictor muscles contact from superior to inferior.
  • The larynx and hyoid bone elevate towards the base of the tongue.
  • food enters to oesophagus when the cricopharyngeus contracts.
  • The duration of the pharyngeal stage is about one second.

4. Oesophageal Stage (involuntary control), in which the food bolus enters the oesophagus.
  • The bolus is moved to the stomach by a squeezing action of the throat muscles.
  • Bolus travels down the eosophagus at a rate of about 3-4 cm/sec.

Note: some suggest another stage occurs before the oral prepatory stage (Leopold & Kagel, 1997). The pre-oral anticipatory stage includes sensory preparation for bolus; this encompasses environmental and behavioural factors that precede the entrance of food into the oral cavity. Pre-oral motor, cognitive, psychosocial and somatoesthetic elements involved during meal times are all included in this pre-oral anticipatory stage. Mackay, Morgan and Burnstien (1999) assert that this stage is of particular importance in reference to clients with dysphagia from a neurogenic origin, as they have an increased likelihood of coinciding cognitive deficits that may affect feeding behaviours and dysphagia.

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