Describe the control of gastrointestinal motility, including sphincter function

Swallowing is divided into three phases:

  • Oral Phase
    • Voluntary
    • Food is pushed against hard palate by tongue
  • Pharyngeal Phase
    • Involuntary
      Coordinated by medulla.
    • Closure of nasopharynx
    • Adduction of vocal cords
    • Hyoid elevation and deflection of epiglottis
    • Pharyngeal contraction
      Propels food bolus towards oesophagus
  • Oesophageal phase
    • Involuntary
    • Closure of UoS
      Resting barrier pressure 100mmHg.
    • Relaxation of LoS
      Resting barrier pressure 20mmHg, which is a balance between:
      • LoS pressure (30mmHg)
      • Antral pressure (10mmHg)
    • Oesophageal peristalsis

Impairment of any of these processes increases risk of aspiration:

  • Obtundation
    Reduced cough reflex.
  • Muscular weakness
  • Impaired medullary coordination


  1. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.
Last updated 2019-07-18

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