1. Anatomy and Physiology of swallowing
Kwong Lee, Lee Fan, Felicity, Camilla, Sai Yan

2. Anatomy and Physiology of swallowing
3 stages:-
Oral phase ( oral preparatory + oral transit )
Pharyngeal phase
Oesophageal phase

3. Oral phase (1): oral preparatory phase
Movement of the mandible (masseter, temporalis, lateral and medial pterygoid muscles)
Formation of food into bolus
Food held anterolaterally against the hard palate
Process requires taste, temperature, touch and proprioreception senses

4. Oral phase (2): oral transit phase
Manipulation of food bolus in central portion of tongue
Sequential anterior to posterior tongue elevation
Triggering pharyngeal reflex as bolus enters pharyngeal phase
Voluntary phase controlled by the cerebral cortex (corticobulbar tract)

5. Pharyngeal phase Reflex < 1s
Stimulation of swallowing receptor areas –tonsillar pillars  brain stem
Closure of the nasal part of the pharynx
Soft palate elevation – levator veli palatini
Pulling forward of the posterior pharyngeal wall – superior constrictor muscle
Contraction of the palatopharyngeal muscle

6. Pharyngeal phase (cont’d)
Larynx pulled upward by contraction of stylopharyngeus, salpingopharyngeus, tyrohyoid and palatopharyngeus muscles
Elevation of the larynx beneath the posteriorly bulging tongue displaces the epiglottis backwards – closure of the larynx

7. Pharyngeal phase (cont’d)
Bolus moves downward over the epiglottis and reach lower part of the pharynx – contraction of superior, middle and inferior constrictor muscles
Upward movement of larynx pulls up and enlarges the opening of the oesophagus
Relaxation of UOS

8. Oesophageal phase Final phase Involuntary
Peristaltic wave from UOS to LOS to stomach - 1° and 2°
1° - continuation of waves from pharynx, controlled by skeletal nerve impulses from IX and X nerve

9. Oesophageal phase (cont’d)
2° - inititated by myenteric nervous system and vagal afferent fibres  medulla vagal efferent
Relaxation of LOS

10. In Summary