1: Neurologic Foundations of Swallowing

Question 1

What are the 3 categories of structures that participate in the involuntary swallow?

Answer 1

1) sensory
2) interneurons
3) motor

Question 2

What are the 3 sensory components of the involuntary swallow?

Answer 2

1) glossopharyngeal CN (pharyngeal branch)
2) vagus nerve - superior laryngeal nerve
3) nucleus tractus solitarius (medulla)

Question 3

What are the 3 interneurons that take part in the pharyngeal swallow?

Answer 3

1) PBN (pons)
2) dorsal swallowing group (DSG)
3) ventral swallowing group (VSG)

Question 4

What role does the DSG play in the involuntary swallow?

Answer 4

initiates the swallow

Question 5

What role does the VSG play in the involuntary swallow?

Answer 5

adapts the swallow

Question 6

What are the 3 motor components of the involuntary swallow?

Answer 6

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)

Question 7

For an involuntary swallow, the bolus enters where and what is stimulated?

Answer 7

oropharynx

mucosa

Question 8

What happens as the head of the bolus passes the anterior faucil pillars?

Answer 8

Involuntary swallow is triggered

Question 9

If there is a delay in triggering the swallow what can happen?

Answer 9

aspiration becomes more likely, other reflexes might get triggered

Question 10

What are other reflexes that could get triggered instead of the swallow?

Answer 10

cough, gag, retch, puke

Question 11

What does the interior branch of the superior laryngeal nerve innervate?

Answer 11

sensory innervation to laryngopharynx and superior part of larynx

Question 12

Where does the right recurrent laryngeal nerve run?

Answer 12

hooks underneath the right subclavian artery then ascends to the larynx

Question 13

Where does the left recurrent laryngeal nerve run?

Answer 13

hooks under the arch of the aorta and loops back up

Question 14

Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is pain information?

Answer 14

Spinal trigeminal nucleus

Question 15

Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is parasympathetic information?

Answer 15

dorsal vagal motor nucleus

Question 16

Action potentials of sensory information from the glossopharyngeal and vagus CNs goes where if it is general sensory and taste information?

Answer 16

nucleus solitarius (NTS)

Question 17

Action potentials from the glossopharyngeal and vagus CNs goes where if it is motor information being sent to skeletal muscles?

Answer 17

Nucleus Ambiguus (NA)

Question 18

What happens in the general sensation pathway?

Answer 18

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

Question 19

What does the “pneumotaxic center” (PBN) during the swallow?

Answer 19

smooth, regular respiration and coordination with the oropharynx

Question 20

The swallow is a ________, so it has to loop back to do what?

Answer 20

reflex

trigger the muscles

Question 21

What are the motor aspects of the involuntary swallow (2)?

Answer 21

Nucleus Ambiguus (IX/X) and motor nucleus of XII

Question 22

The NA and Motor nucleus of XII receive sensory information from where and send it where?

Answer 22

interneurons - VSG and DSG

send to muscle pairs in oropharynx, larynx, and esophagus

Question 23

The pharyngeal branches of the vagus nerve innervate what?

Answer 23

motor innervation of majority of pharynx and soft palate muscles, including palatoglossus

Question 24

The right and left recurrent laryngeal nerves innervate what?

Answer 24

majority of intrinsic laryngeal muscles

Question 25

The hypoglossal nerve (motor nuclei of XII) innervates what?

Answer 25

all of the intrinsic muscles of the tongue excluding palatoglossus

Question 26

Once the swallow reflex is triggered, the _____________ doesn’t _______, but the ________ of contraction can change through a peripheral _____________ ______.

Answer 26

sequence
change
strength
feedback loop

Question 27

When someone hears the command “please swallow” where is the information in the brain going to start the process of producing the swallow

Answer 27

Has to go through auditory and language centers, and then will go to the prefrontal cortex.

Question 28

Where will the AP for a volitional swallow go after the prefrontal cortex?

Answer 28

Premortor cortex to supplementary areas to primary motor cortex

Question 29

What 2 things happen in the premotor cortex/supplementary motor area with the volitional swallow?

Answer 29

1) makes trunk/positioning movement

2) planning complex movement and adapting to different environmental situations

Question 30

What are the two loops of the motor hierarchy?

Answer 30

1) cerebellar

2) basal ganglia

Question 31

Where do the upper motor neurons synapse?

Answer 31

brainstem - medulla - central pattern generator