Swallowing

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

References

1. Chambers D, Huang C, Matthews G. Basic Physiology for Anaesthetists. Cambridge University Press. 2015.