Anatomy and Physiology of swallowing

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Anatomy and Physiology of swallowing

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

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Anatomy and Physiology of swallowing

• 3 stages-
• Oral phase ( oral preparatory oral transit )
• Pharyngeal phase
• Oesophageal phase

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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

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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)

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Pharyngeal phase

• Reflex lt 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

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Pharyngeal phase (contd)

• 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

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Pharyngeal phase (contd)

• 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

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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

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Oesophageal phase (contd)

• 2 - inititated by myenteric nervous system and
  vagal afferent fibres ? medulla? vagal efferent
• Relaxation of LOS

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In Summary