oral, pharyngeal and oesophageal physiolgoy and dysphagia Flashcards
what 3 phases are there in a normal swallow?
oral, pharyngeal, oesophageal
oral phase of swallowing : muscle, neural control and voluntary control
- striated muscle
- neural control = cortex/medulla
- full voluntary control
pharyngeal phase of swallowing : muscle, neural control and voluntary control
- striated muscle
- neural control = medulla
- some voluntary control
oesophageal phase of swallowing : muscle, neural control and voluntary control
- striated/smooth muscle
- neural control = medulla/ENS (mainly vagal nerve and ENS)
- no voluntary control
what are the 3 components of preparation of bolus and initiation of swallowing in the oral phase?
chewing, salivation, movement of bolus
what is the function of chewing? effectors?
- prepare solid food for transfer through pharynx
- effectors = teeth, jaws masseter muscles
what is the function of salivation? effectors?
- lubricate bolus and begin digestion
- mucus, amylase, lipase, water, HCO3-
what is the function of bolus movement? effectors?
deliver prepared bolus to oropharynx — tongue
describe the upper oesophageal sphincter (UOS)
- pressure = 100mmHg (atm = 0)
- relatively high pressure zone
- protects are ability to avoid laryngopharyngeal reflux (reflux from oesophagus into airway)
- opens as pharyngeal phase starts
describe intraoesophageal pressure
-5mmHg
- -ve pressure — as longs and pleura pull against oesophagus
- bolus pulled into oesophagus
describe the lower oesophageal sphincter (LES)
- pressure = 20mmHg
- pressure higher than intragastric pressure
- opens to allow food to enter stomach
- barrier to avoid intragastric contents entering into oesophagus = reflux
what do sphincters do?
prevent influx of air and reflux of gastric contents into the oesophagus
what has the role of organising in the neuroanatomy of swallowing?
brain stem central programme generator (CPG)
what cranial nerves are involved in swallowing?
V, VII, IX, X, XII — have input from sensory receptors in oropharynx, larynx and oesophagus
what is a main afferent relay centre?
nucleus solitarius (X)
what efferent nucleus is very critical in swallowing, and damage to it can cause severe dysphagia?
nucleus ambiguous (IX, X)
mid to low oesophagus is mainly under what neural input?
enteric nervous system — vagal and spinal pathways
what 2 nuclei in the brain are important efferent centres for the oesophagus?
dorsal motor nucleus and nucleus ambiguous
peristalsis is the result of what?
excitation and inhibition in parallel
how are swallowing regions in the brain organised?
topographically
what does function MRI (FMRI) look at?
areas associated with increased changes in BOLD (blood oxygen level dependency)