Anatomy and Physiology of swallowing

Kwong Lee, Lee Fan, Felicity, Camilla, Sai Yan

Anatomy and Physiology of swallowing

• 3 stages:-

Oral phase ( oral preparatory + oral transit )

Pharyngeal phaseOesophageal phase

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

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)

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

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

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

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

Oesophageal phase (cont’d)

• 2° - inititated by myenteric nervous system and vagal afferent fibres medulla vagal efferent

• Relaxation of LOS

In Summary