Cranial Nerve Review

Question 1

what are the motor cranial nerves involved in swallowing?

Answer 1

trigeminal, facial, vagus, and hypoglossal

Question 2

what are the sensory receptors associated with swallowing?

Answer 2

mechanoreceptors – respond to touch
proprioceptors – sense positions of the articulators
stretch receptors – respond to changes in muscle lengths
thermoreceptors – detect difference in temperature
nocioreceptors – respond to pain
chemoreceptors – respond to taste

Question 3

what is the path of the motor signal for swallowing?

Answer 3

Motor Cortex → brain → to brainstem (decussation) → motor nucleus (LMN) → project through cranial nerve → motor muscles

Question 4

what is the path for sensory signals for swallowing?

Answer 4

Receptors → brain stem → up to sensory cortex → motor cortex → etc.

Question 5

what are the branches of the vagus nerve?

Answer 5

1. superior laryngeal - internal branch and external branch

2. recurrent laryngeal nerve - courses around the aorta and under subclavian artery

Question 6

what is the function of the internal branch within the superior laryngeal?

Answer 6

sensory of the area above the vocal folds

Question 7

what is the function of the external branch of the superior laryngeal branch?

Answer 7

motor to cricothyroid muscles

Question 8

what are the sensory and motor functions of the trigeminal nerve in regard to swallowing?

Answer 8

sensory: three branches that respond to sensation of the face, nasal, and oral cavities
motor: motor of the muscles of mastication and tensor deli palatini

Question 9

what are the sensory and motor functions of the facial nerve in regard to swallowing?

Answer 9

sensory: sensation of the anterior 2/3 of the tongue
motor
- muscles of facial expression
- posterior belly of digastricus, stylohyoid
- submandibular and sublingual salivary glands

Question 10

what are the sensory and motor functions of the vagus & glossopharyngeal nerves in regard to swallowing?

Answer 10

sensory

• sensation of taste from posterior 1/3 of the tongue and touch sensation of the mucosa or soft palate and facial pillar regions
• tactile sensation of the pharynx, larynx, esophagus, and external ear

motor

• stylopharyngess (shortens pharynx) (CN IX) and parotid salivary gland (CN IX)
• velar musculature (CN X)

Question 11

what is the motor function of the hypoglossal nerve in regard to swallowing?

Answer 11

intrinsic and extrinsic tongue muscles (expect palatoglossus)

Question 12

how would you test the sensory function of the trigeminal nerve?

Answer 12

have client close eyes; touch a variety of spots on the face and in the mouth (e.g. tongue, cheek, forehead, jaw)

Question 13

how would you test the motor function of the trigeminal nerve?

Answer 13

palpate the temporals muscle and ask the client to clench their teeth so you can feel the contraction as well as left or right symmetry

Question 14

how would you test the sensory & motor functions of the facial nerve?

Answer 14

sensory
- cotton swabs with vinegar, lemon, sugar, and bitters can be used (not often tested by SLP)

motor
- smile and pucker or “oo-ee” sequences

Question 15

how would you test the sensory and motor functions for the vagus & glossopharyngeal nerves?

Answer 15

sensory - no good test

motor - cough, nasal air emission, phonation

Question 16

how would you test the motor function of the hypoglossal nerve?

Answer 16

test by tongue protrusion, lateralization, tongue tip elevation, and strength against resistance

Question 17

what is the clinical importance of CN V function for swallowing?

Answer 17

sensory: bolus sensation & pocketing
motor: chewing, preventing nasal regurgitation, and stabilizing the jaw for hyoid movement

Question 18

what is the clinical importance of CN VII for swallowing?

Answer 18

sensory: taste sensation (motivation) for eating and drinking
motor: oral seal for pressure generation and bolus

Question 19

what is the clinical importance of CN X and CN IX for swallowing?

Answer 19

sensory: initiation of the pharyngeal swallow and airway protection
motor: saliva production, pharyngeal bolus propulsion, laryngeal elevation and airway protection; upper esophageal sphincter relaxation and opening

Question 20

what is the clinical importance of the hypoglossal nerve for swallowing?

Answer 20

bolus manipulation, formation, containment & transfer

Question 21

pharyngeal swallowing is controlled and triggered by a complex system of neurons in the ____________ _______________ of the brainstem called the …

Answer 21

reticular formation; central pattern generator (CPG)

Question 22

what is the CPG?

Answer 22

a biological neural network that produces rhythmic patterned outputs without sensory feedback, meaning once swallowing starts, this patterned response kicks in and we can’t stop it

Question 23

what are the two main groups of interneurons that the CPG is organized into?

Answer 23

dorsal swallowing group & ventral swallowing group

Question 24

what is the dorsal swallowing group & where is it located?

Answer 24

involved in triggering, shaping, and the timing of the sequential swallowing pattern; gives the correct instructions to the ventral swallowing group
- located in the nucleus tracts solitarius of the medulla

Question 25

what is the ventral swallowing group & where is it located?

Answer 25

involved in distributing the motor drive to other motoneurons in the brainstem which execute the motor events involved in swallowing
- located in the ventrolateral medulla

Question 26

the DSG receives sensory information from…

Answer 26

CN V: tactile sensation of hard & soft palate & anterior 2/3 order tongue)
CN VII: taste (anterior 2/3 of tongue)
CN IX: taste and sensation from posterior 1/3 of tongue, tactile sensation or oropharynx
CN X: tactile sensation oft he larynx, pharynx, and base of the tongue

Question 27

what motor actions does the VSG command of each CN based on information from the DSG?

Answer 27

CN V: jaw closing, soft palate elevation, hyoid elevation
CN VII: hyolaryngeal elevation
CN IX/X: soft palate elevation, hyoid elevation, pharyngeal contraction/shortening, UES opening, VF closure)
CN XII: tongue driving forces
C1-3 hyolaryngeal elevation