1: Neurologic Foundations of Swallowing Flashcards
What are the 3 categories of structures that participate in the involuntary swallow?
1) sensory
2) interneurons
3) motor
What are the 3 sensory components of the involuntary swallow?
1) glossopharyngeal CN (pharyngeal branch)
2) vagus nerve - superior laryngeal nerve
3) nucleus tractus solitarius (medulla)
What are the 3 interneurons that take part in the pharyngeal swallow?
1) PBN (pons)
2) dorsal swallowing group (DSG)
3) ventral swallowing group (VSG)
What role does the DSG play in the involuntary swallow?
initiates the swallow
What role does the VSG play in the involuntary swallow?
adapts the swallow
What are the 3 motor components of the involuntary swallow?
1) nucleus ambiguus - IX and X (medulla)
2) motor nucleus - XII (medulla)
3) neuromuscular junctions (25 pairs of muscles in oropharynx, larynx, and esophagus that make precisely timed movements)
For an involuntary swallow, the bolus enters where and what is stimulated?
oropharynx
mucosa
What happens as the head of the bolus passes the anterior faucil pillars?
Involuntary swallow is triggered
If there is a delay in triggering the swallow what can happen?
aspiration becomes more likely, other reflexes might get triggered
What are other reflexes that could get triggered instead of the swallow?
cough, gag, retch, puke
What does the interior branch of the superior laryngeal nerve innervate?
sensory innervation to laryngopharynx and superior part of larynx
Where does the right recurrent laryngeal nerve run?
hooks underneath the right subclavian artery then ascends to the larynx
Where does the left recurrent laryngeal nerve run?
hooks under the arch of the aorta and loops back up
Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is pain information?
Spinal trigeminal nucleus
Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is parasympathetic information?
dorsal vagal motor nucleus
Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is general sensory and taste information?
nucleus solitarius (NTS)
Action potentials from the glossopharyngeal and vagus CNs goes where if it is motor information being sent to skeletal muscles?
Nucleus Ambiguus (NA)
What happens in the general sensation pathway?
1) APs travel along CNs to synapse in the medulla
2) specifically, the NTS, which then sends interneurons to the following areas:
- pneumotaxic center (PBN)
- DSG
- VSG
What does the “pneumotaxic center” (PBN) during the swallow?
smooth, regular respiration and coordination with the oropharynx
The swallow is a ________, so it has to loop back to do what?
reflex
trigger the muscles
What are the motor aspects of the involuntary swallow (2)?
Nucleus Ambiguus (IX/X) and motor nucleus of XII
The NA and Motor nucleus of XII receive sensory information from where and send it where?
interneurons - VSG and DSG
send to muscle pairs in oropharynx, larynx, and esophagus
The pharyngeal branches of the vagus nerve innervate what?
motor innervation of majority of pharynx and soft palate muscles, including palatoglossus
The right and left recurrent laryngeal nerves innervate what?
majority of intrinsic laryngeal muscles
The hypoglossal nerve (motor nuclei of XII) innervates what?
all of the intrinsic muscles of the tongue excluding palatoglossus
Once the swallow reflex is triggered, the _____________ doesn’t _______, but the ________ of contraction can change through a peripheral _____________ ______.
sequence
change
strength
feedback loop
When someone hears the command “please swallow” where is the information in the brain going to start the process of producing the swallow
Has to go through auditory and language centers, and then will go to the prefrontal cortex.
Where will the AP for a volitional swallow go after the prefrontal cortex?
Premortor cortex to supplementary areas to primary motor cortex
What 2 things happen in the premotor cortex/supplementary motor area with the volitional swallow?
1) makes trunk/positioning movement
2) planning complex movement and adapting to different environmental situations
What are the two loops of the motor hierarchy?
1) cerebellar
2) basal ganglia
Where do the upper motor neurons synapse?
brainstem - medulla - central pattern generator
