(15) CN V, VII, IX, X, XI, XII

Question 1

at what brainstem level is the trigeminal nuclei found

Answer 1

mid pons

Question 2

path of CN V motor fibers

**esp foramen

Answer 2

trigeminal nuclei → V3 → exits cranium via foramen ovale → muscles of mastication (masseter and temporalis muscles); tensor tympani (dampens sound); tensor veli palatine; mylohyoid; anterior belly of diagastric

Question 3

What is the jaw jerk reflex?

Answer 3

tapping on masseter muscle (or temporalis????) stretches muscle spindles → signal travels via afferent fibers to mesencephalic nucleus of V → interneuron sends signal to motor neuron nucleus in motor nucleus → impule for masseter to contract

Question 4

How is CN V tested?

Answer 4

bite down to test jaw strength (do bilaterally)

Question 5

travels on floor of meckel’s cave

Answer 5

CN V motor fibers as V3 (mandibular branch)

Question 6

UMN input to trigeminal motor nuclei is (uni or bi)

Answer 6

bilateral

Question 7

where must a lesion be in order to cause UNIlateral weakness in jaw closure

Answer 7

CN V or its nuclei

Question 8

CN VII motor neurons arise in ______ nucleus in the _____ level of the brain stem to innervate ______

Answer 8

facial nucleus at the mid pons to innv muscles of facial expression

Question 9

CN VII parasympathetic fibers CN VII motor neurons arise in ______ nucleus in the _____ level of the brain stem to innervate ______

Answer 9

salivary nucleus at the rostral medulla to innv lacrimal and salivary glands

Question 10

travels through the nervus intermedius

Answer 10

parasympathetic fibers on CN VII

Question 11

Where does CN VII and nervus intermedius exit the brainstem

Answer 11

pontomedulalry junction at the cerebellopontine angle

Question 12

What is the facial colliculus

Answer 12

the bump on the floor of the 4th ventricle caused by the fibers of the facial N looping over the abducens

Question 13

CN VII exits the cranial vault via

Answer 13

internal auditory meatus → auditory canal where it bends ventrally to exit the skull via the stylomastoid foramen

Question 14

primary parasympathetic neurons serving salivary and lacrimal glands synapse with secondary neurons in _____ nucleus

Answer 14

sphenopalatine and submandibular ganglion

Question 15

how is CN VII tested

Answer 15

ask pts to wrinkle forehead, close eyes tightly, show their teeth (movements should be symmetric)

Question 16

CN VII leasion will cause the eye opening to inc or dec at rest

Answer 16

increase

Question 17

consequence of unilateral motor cortex or corticobulbar fibers (UMNs) on the muscles of facial expression

Answer 17

forehead will be spared but lower facial muscles will be weak on the contralateral side

Question 18

consequence of unilateral LMN fiber lesion of CN VII

Answer 18

ipislateral weakness of forehead and lower facial muscles

Question 19

CN IX motor neurons arise in ______ nucleus in the _____ level of the brain stem to innervate ______

Answer 19

nucleus ambiguus which is near the junction of the pons and medulla to innervate the stylopharyngeus muscles

Question 20

CN IX parasympathetic pre gang neurons arise in ______ nucleus in the _____ level of the brain stem travels via ______ to _____ ganglion where it synapses with post gang fibers that will innervate _____

Answer 20

inferior salivary nucleus at the midline of the medulla → CN IX → lesser petrosal N → otic ganglion to innervate the parotid gland

Question 21

UMN and LMN lesions to CN IX will clinically manifest as

Answer 21

dysphagia

Question 22

How is CN IX tested?

Answer 22

eliciting a gag reflex (although this is sensory IX and mostly motor X, but with some IX)

Question 23

CN X motor neurons arise in ______ nucleus in the _____ level of the brain stem to innervate ______

Answer 23

nucleus ambiguus in the lateral medulla to innv muscles of the soft palate, larynx, and pharynx

Question 24

CN X parasympathetic pre gang neurons arise in ______ nucleus in the _____ level of the brain stem travels via ______ to _____ ganglion where it synapses with post gang fibers that will innervate _____

Answer 24

dorsal motor nucleus at the midline medulla → pre gang travel with CN X to intramural ganglia assc with heart, lung, digestive tract to innv tissues in the organs

Question 25

where does CN X exit the brainstem

Answer 25

between the inferior olive and the inferior cerebellar peduncle

Question 26

CN X exits the skull via

Answer 26

jugular foramen

Question 27

CN X has bi or unilateral UMN innvervation

Answer 27

bilateral

Question 28

where will a lesion be found that produces dysphagia, hoarseness, and inability to elevate the soft palate. (will these symptoms be on the ipsilateral or contralateral side)

Answer 28

LMN CN X with the signs on the ipsilateral side

UMN has bilateral input

Question 29

CN XI has motor fibers that originate in _____ nuclei which are found…

Answer 29

nucleus ambiguus in the lateral medulla

spinal accessory nuclei in the intermediolateral gray matter (btwn ventral and dorsal horns) of C1-C5

**fibers from these 2 areas join together to form the spinal accessory nerve

Question 30

Where do CN XI fibers exit the spinal cord and where do they go?

Answer 30

exit between the dorsal and ventral roots to ascend along the spinal cord enter the cranium via the foramen magnum then exit via the jusgualr foramen to innervate SCM and trapezius

*note the fibers from the ambiguus nucleus join CN XI only for a short while before joining with CN X (→ jugular foramen)

Question 31

How is CN XI tested?

Answer 31

elevating the shoulders and turning the head

Question 32

how will and LMN CN XI lesion present?

Answer 32

ipsilateral weakness in elevating shoulder; weakness in rotating head away from the lesion; may see atrophy of SCM and trapezius

Question 33

how will and UMN CN XI lesion present?

Answer 33

contralateral weakness in elevating the shoulder and weakness in rotating head away from the lesion (ipsilateral SCM weakness)

Question 34

CN X motor neurons arise in ______ nucleus in the _____ level of the brain stem and exit brain stem at to innervate ______

Answer 34

hypoglossal nucleus at the medulla

exit brainstem between the inferior olives and the pyramids (nerve found at the junction of the medulla and the spinal cord)

innervates the tongue (intrinsic and extrinsic muscles)

Question 35

CN XII exits the cranium via…

Answer 35

hypoglossal foramen

Question 36

diff in presentation of a LMN vs UMN lesion of CN XII

Answer 36

LMN: tongue points towards the side of the lesion

UMN: tongue points away from the side of the lesion
**this is bc the corticobulbar fibers from the motor cortex cross over to the contralateral hypoglossal nuclei