CNs IX-XII

Question 1

CN XII axon type, origin, and termination

Answer 1

general somatic efferent; hypoglossal nucleus (rostral medulla) to the tongue muscles

Question 2

main muscles of tongue protrusion

Answer 2

genioglossus muscle

Question 3

hypoglossal n. exits the brainstem adjacent or lateral to the _____

Answer 3

pyramids

Question 4

hypoglossal n. (lower motor neuron) lesion results in:

Answer 4

• deviation toward lesion
• fasciculations
• atrophy

Question 5

corticobulbar (upper motor neuron) lesion results in:

Answer 5

• deviation toward opposite side of UMN lesion
• no fasciculations
• minimal atrophy

Question 6

CN XI axon type, origin, and termination

Answer 6

special visceral efferent; accessory nucleus in cervical spinal cord (caudal medulla to about C5) to sternomastoid and trapezius mm.

Question 7

effect of accessory nerve lesion on the trapezius muscle

Answer 7

• scapula and clavicle hang due to weak trapezius
• weak shoulder shrug; levator scapulae working alone
• muscle atrophy leads to scalloped appearance of neck contour

Question 8

efferent axon types, origins and terminations for CN IX

Answer 8

1. special visceral efferent (branchial motor) from nucleus ambiguus to stylopharyngeus (in pharynx)
2. general visceral efferent from inferior salivatory nucleus (preganglionic parasympathetics) to the otic ganglion; postganglionic parasympathetics from otic ganglion to the parotid gland

Question 9

afferent axon types, origins, and terminations for CN IX

Answer 9

1. general somatic afferent; from mucosa of post 1/3 of tongue, pharynx and middle ear, skin of the outer ear; to the spinal trigeminal nucleus
2. general visceral afferent; from carotid body and sinus to nucleus of the solitary tract
3. special sensory afferent- taste buds of post 1/3 of tongue to nucleus of solitary tract

Question 10

afferent axon types, origins, and terminations for CN X

Answer 10

1. general somatic afferent from skin of the outer ear to superior ganglion of X to spinal trigeminal nucleus
2. special visceral afferent from epiglottis and esophagus taste buds to inferior ganglion of X, to nucleus of solitary tract
3. general visceral afferent from thoracic/abdominal viscera; mucous of larynx/pharynx; stretch receptors on aortic arch; chemoreceptors on aortic bodies to inferior ganglion of X, to nucleus of solitary tract

Question 11

efferent axon types, origins, and terminations for CN X

Answer 11

1. special visceral efferent from nucleus ambiguus to larynx and pharynx
2. general visceral efferent from thoracic/abdominal viscera, smooth m and glands to dorsal motor nucleus of the vagus and nucleus ambiguus

Question 12

components of CNs ___, ____, and ____ are in the spinal trigeminal tract

Answer 12

VII, IX, and X

Question 13

nucleus ambiguus contains:

Answer 13

special visceral efferent cell bodies for CNs IX and X; also general visceral efferent cell bodies for CN X

Question 14

afferent and efferent components of the gag reflex

Answer 14

CN IX is the afferent limb, CN X is the efferent limb

Question 15

____ and ____ are processed in the nucleus of the solitary tract

Answer 15

visceral afferents; taste

Question 16

blood supply to lateral and medial midbrain

Answer 16

lateral: posterior cerebral a.
medial: basilar a.