Vagus Nerve X

Question 1

Where are LMN located and what do they innervate?

Answer 1

In nucleus ambiguus, they innervate the skeletal muscles of 1.) Soft palate

2. ) Larynx
3. ) Pharynx
4. ) Vocalis muscle (true vocal cords)

Question 2

Where is Nucleus ambiguus located and list the CN that have LMN within it

Answer 2

Reticular formation,

Lower motor neurons of CN IX, CN X, cranial part of CN XI

Question 3

Where are the preganglionic parasympathetic cell bodies primarily located

Answer 3

Dorsal motor nucleus of X

Question 4

Axons of preganglionic parasympathetic cell bodies exit the medulla and synapse where?

Answer 4

Exit the medulla as rootlets of X and synapse on postganglionic neurons in visceral walls of glands, cardiac muscle, and smooth muscle of the thorax and abdomen

Question 5

Sensory fibers of CN X travel along what tract and end where?

Answer 5

Solitary tract and end in the solitary nucleus

Question 6

The sensory fibers of CN X traveling along the solitary tract carry pain and pressure from where?

Answer 6

Pharyx, larynx, thorax, and abdomen

Question 7

UMN innervate what bilaterally, making a unilateral lesion of the UMN not easily noticed.

Answer 7

the nucleus ambigous

Question 8

What are the important reflexes affiliated with CN X? (3)

Answer 8

1. ) Carotid sinus reflex
2. ) Carotid Body reflex
3. ) Cough, gag, and vomiting reflexes

Question 9

What CN carries the efferent part of the carotid sinus reflex to the heart?

Answer 9

CN X

Question 10

What CN carries the afferent part of the carotid sinus reflex to the heart?

Answer 10

CN IX

Question 11

In regards to the Carotid sinus reflex where does the afferent limb originate?

Answer 11

From baroceptors along the carotid artery near the bifurcation into internal and external carotid arteries

Question 12

Afferent information is carried by fibers of CN IX to where?

Answer 12

The solitary nucleus, then relayed to the dorsal motor nucleus of X

Question 13

The efferent limb of the carotid sinus reflex arc innervates the heart to slow or speed up heart rate?

Answer 13

slow heart rate

Question 14

The Carotid body reflex involves chemoreceptor sensation from where?

Answer 14

Lung Bronchioles

Question 15

The one sensory (afferent) component of the Carotid Body Reflex synapses where?

Answer 15

In the “medullary respiratory center” (an area of reticular formation)

Question 16

What does the Carotid Body Reflex control?

Answer 16

Breathing Rhythm, the efferent limb is via decending info to spinal cord levels controlling inspiration (intercostals and diaphragm)

Question 17

The cough, gag and vomiting reflexes involve sensory fibers from where?

Answer 17

Oral/nasal cavity (CN IX)
The Gut (CN X)

Question 18

How does the cough, gag, and vomiting reflex work?

Answer 18

Sensory info is relayed to appropriate LMN in Nucleus Ambiguous and spinal cord and preganglionic parasympathetics in dorsal motor nucleus of X

Question 19

Do lesions of CN X result in sensory, motor, or both deficits?

Answer 19

Both sensory and motor deficits

Question 20

What do unilateral lesions of LMN in CN X result in?

Answer 20

Difficult in swallowing, hoarseness (dysphonia), inability to raise the soft palate on the IPSILATERAL side

Question 21

Lesions of preganglionic parasympathetic fibers of CN X cause what?

Answer 21

Disruption of some gut reflexes

Question 22

Lesions of the preganglionic parasympathetic fibers are less important for diagnosis of lesion location but are more significant in identifying what?

Answer 22

Deficits associated with the somatomotor LMN component

Question 23

Hyperactivity (excess firing) can cause what?

Answer 23

Excess gastric acid secretion = ulcers

Question 24

Large bilateral lesions of the medullary reticular formation can disrupt what?

Answer 24

Normal breathing rhythms and reflex control of vascular resistance to blood flow, resulting in a coma
—patients with this type of damage may need life support systems and have a poor prognosis