Cranial Nerves IX, X, XI, XII

Question 1

axon type, origin, and periph termination of CN XII

Answer 1

GSE
hypoglossal nucleus
tongue mm

Question 2

what does genioglossus m do?

Answer 2

is main m innervated by XII, does tongue protrusion

Question 3

hypoglossal nerve fibers

Answer 3

• neuronal cell bodies in hypoglossal nucleus

- exits adjacent to pyramid

Question 4

hypoglossal nerve lesion

Answer 4

• lower motor neuron
• deviation toward side of lesion
• fasciculations

Question 5

hypoglossal corticobulbar fibers

Answer 5

• corticobulbar fibers from motor cortex

- decussate adjacent to hypoglossal nucleus

Question 6

hypoglossal corticobulbar fiber lesion

Answer 6

• upper motor neuron
• deviate contralateral side as lesion
• no fasciculations
• minimal to no atrophy

Question 7

axon type, CNS origin, periph term of CN XI

Answer 7

• SVE
• accessory nucleus in cervical SC (caudal medulla to C5)
• sternomastoid, trapezius (enters foramen magnum, into skull, exit via jugular foramen)

Question 8

lesion in CN XI

Answer 8

• scapula and clavicle hang due to weak trap
• weak shoulder shrug as levator scap must work alone
• m atrophy = scalloped neck contour

Question 9

axons, CNS origin/term, Peripheral origin/term for CN IX

Answer 9

1. SSA - nucleus of solitary tract - tastebuds post 1/3 of tongue
2. GVA - nuc of solitary tract - carotid body and sinus
3. GSA - spinal trigem nucleus - mucosa post 1/3 tongue, pharynx and mid ear, skin of outer ear
4. GVE - inf salivatory nucleus, otic ganglion - parotid gland
5. SVE - nucleus ambiguus - pharynx (stylopharyngeus)

Question 10

somatic afferents of IX

Answer 10

• skin of ear and middle ear (sup gang of IX, trigem spinal nucleus)
• circumvallate papillae

Question 11

visceral afferents of IX

Answer 11

• carotid body: blood O2, CO2, pH

- carotid sinus: changes in BP (inf gang of glossopharyngeal n and solitary nucleus)

Question 12

special visceral efferents

Answer 12

nucleus ambiguus (stylopharyngeus m-elevate pharynx in speech and swallowing)

Question 13

general visceral efferents

Answer 13

inf salivatory nucleus (otic ganglion-parotid salivary gland)

Question 14

glossopharyngeal neuralgia

Answer 14

• similar to trigem meuralgia
• suddent burst of pain in post tongue/wall of pharynx, radiates to ear
• attacks precipitated by swallowing/talking
• pharmacologic management or tractotomy of spinal trigem tract in caudal medulla

Question 15

soamtic afferents of CN X

Answer 15

• skin of ear (sup gang of X, trigem spinal nucleus
• epiglottis
• thoracic and abdominal viscera
• aortic arch baroreceptors BP and chemoreceptors (inf gang of X, solitary nucleus of X

Question 16

efferents of X

Answer 16

• nucleus ambiguus (lateral) (mm of speech and swallowing
• nucleus ambigiuus (medial) (heart and lungs
• dorsal motor nucleus of vagus (all viscera up to trans colon)

Question 17

tongue thrust reflex

Answer 17

• in infants to 8 years
• can lead to speech/ortho problems
• afferent limb: CN V or IX
• efferent limb: CN XII
• is repsonse to stim of pharynx wall

Question 18

gag reflex

Answer 18

• CN IX: afferent
• CN X: efferent component
• central connection not clear
• touch one side of pharynx, elicit bilat response