Phases of Swallowing

i. Oral Preparation

   - Involve: jaw, lips, tongue, and soft palate 

   - Function: retaining, controlling, and manipulating food and drink within the oral cavity.

 

Jaw

Opening and closure of the mouth

Lateral, rotatory movements are involved in chewing

Lips

Assist with taking material into the mouth

Retaining materials to prevent spillage or drooling

Tongue

Moves food from side to side 

Helps clear material from the teeth and the crevices of the mouth.

Soft Palate

Prevents material falling into pharynx too early

Saliva

Lubricate dry materials to allow for a smooth transit


ii. Oral Transit

   - Oral transit phase occurs once preparation is complete. 

  - A bundle of material, or bolus, is formed and held in the midline of the tongue. 

   - The front, back, and sides of the tongue are elevated to form a well for the bolus.

   - The bolus is propelled towards the pharynx by backward motion of the tongue. 

   - The tongue press excessively against the hard palates and upper jaw and push the bolus backwards.

   - The soft palate rises to prevent material entering the nasal cavity.   

iii. Pharyngeal Phase

    • Upward movement of the larynx helps to relax the muscle at the top of the oesophagus (upper oesophageal sphincter).
    • Epiglottis closes over the closed larynx, diverting the bolus towards the oesophagus.
  • Muscular pharyngeal walls exert pressure on the bolus, pushing it into the oesophagus.
  • Once the bolus is passed through the sphincter, the airway reopens and breathing resumes.

iv. Oesophageal Phase 

- Allows transport of the bolus through the oesophagus to the stomach. 

- Movement via a series of waves of muscular contractions - peristalsis. 

- The muscles below the bolus relax, and above the bolus contract until the bolus reaches the stomach.


References:

Humbert, I. A. (2011). Stimulating Swallowing: Essential Central and Peripheral Nervous System Targets. ASHA Leader, 16(9), 10-13. 

Rousseau, B., & Branski, R. (2018). Anatomy and physiology of speech and hearing. New York: Thieme. 

Standring, S. (2012). Studyguide for Grays Anatomy: The anatomical basis of clinical practice by Standring, Susan, ISBN: 9781478418030: Study guide. Amazon. Retrieved from https://www.amazon.com/Grays-Anatomy-Anatomical-Clinical-Practice/dp/0702052302