Swallowing Flashcards
What are the phases of swallowing?
Oral preparatory phase
Pharyngeal phase
Oesophageal phase
Is the oral preparatory phase voluntary or involuntary?
Voluntary
What happens in the oral preparatory phase?
Tongue pushes bolus posteriorly and superiorly towards pharynx
When does the pharyngeal phase begin?
When the bolus touches the wall of the pharynx
Is the pharyngeal phase voluntary or involuntary?
Involuntary
What happens in the pharyngeal phase?
Soft palate moves upwards, closes the nasopharynx
The pharyngeal muscles contract, reduce lumen of pharynx
Larynx moves upwards
Vocal cords adduct, close airways
Epiglottis lies over opening of larynx
Upper oesophageal sphincter relaxes
Why does the soft palate move upwards and close off the nasopharynx?
To prevent the bolus from moving upwards into the nasal cavity
Why do the pharyngeal constrictor muscles contract and reduce the lumen of the pharynx?
To push the bolus downwards
How does the larynx move upwards?
Contraction of suprahyoid muscles
Why do the vocal cords adduct and close the airways?
To prevent the bolus from entering the airways
Why does the epiglottis lie over the opening of the larynx?
To prevent the bolus from entering the airways
Why does the upper oeosphageal sphincter relax?
To open up the oesophagus so the bolus can pass into it
When does the oesophageal phase begin?
When the bolus has passed the upper oesophageal sphincter and entered the oesophagus
Is the oesophageal phase voluntary or involuntary?
Involuntary
What happens in the oesophageal phase?
Upper oesophageal sphincter contracts
Oesophagus muscular wall pushes bolus down by peristalsis
What happens in peristalsis in the oesophagus?
Smooth muscle above bolus contracts
smooth muscle below bolus relaxes
this pushes the bolus down the oesophagus
What is the control of swallowing?
Neural control
- mechanoreceptors
- sensory nerve fibres
- autonomic nerve fibres
- pharyngeal constrictor muscles
Where are the mechanoreceptors involved in the control of swallowing located?
Pharynx
What carries sensory information from the pharynx to the CNS?
CN9 Glossopharyngeal nerve
Where in the CNS does the CN9 glossopharyngeal nerve carry sensory information from the pharynx to?
Medulla
What carries motor information from the medulla to the pharyngeal constrictor muscles?
CN10 vagus nerve
What does the neural control of swallowing follow the same pathway as?
Gag reflex
What is dysphagia?
Difficulty swallowing
What is a common cause of dysphagia?
Stroke
Why can a stroke cause dysphagia?
Damages the part of the brain involved in the neural control of swallowing
