Swallowing
Oral (voluntary)
Tongue pushes food bolus into pharynx
Pharyngeal (involuntary)
innervation: CN IX, X
Mechanoreceptors in pharynx send impulse via CN IX, X to:
Swallowing centre in medulla
- Inhibits respiration
- Raises the larynx + hyoid
- Closes the glottis
- Raises soft palate to close off nasopharynx
- Opens the upper oesophageal sphincter
movements:
- soft palate elevates
- true vocal cords close
- pharyngeal constrictors constrict
- epiglottis pushed by food bolus over tracheal opening
In neonates, larynx is high in the neck + epiglottis is superior to soft palate → babies can suckle and breathe at the same time
Oesophageal (involuntary)
innervation: vagus nerve
Peristaltic wave control - vagus nerve, enteric plexus
movements:
- larynx lowers back to normal position
- cricopharyngeus muscle contracts
- food bolus moved down oesophagus via peristalsis
Peristaltic wave from oesophageal preceded by signals from myenteric inhibitory neurons - stomach relaxation