CN V and VII

Question 1

What does CN V transmit?

Answer 1

tactile, proprioceptive, pain, temp from head to cortex

Question 2

3 divisions of CN V

Answer 2

ophthalmic (V1) -> upper face, sensory only
maxillary (V2) -> middle face, sensory
Mandibular (V3) -> Lower face, sensory and motor

Question 3

CN V fiber types

Answer 3

mesencephalic nucleus of trigeminal tract, trigeminal main sensory nucleus and trigeminal motor nucleus

Question 4

Where happens if there is a lesion in motor components of CN V?

Answer 4

jaw closure weakened, opened jaw will deviate toward side of lesion

Question 5

Where do cell bodies of CN V motor nucleus terminate?

Answer 5

mm of mastication

Question 6

Which CN V nucleus is part of reticular formation?

Answer 6

supratrige minal nucleus

Question 7

What is the supratrige minal nucleus a pattern generator for?

Answer 7

masticatory rhythm

Question 8

Where does the centrally directed process of mesencephalic nucleus of CN V (sensory afferent) terminate?

Answer 8

trigeminal motor nucleus (jaw jerk reflex) and supratrigeminal nucleus (chewing movements)

Question 9

What does mesencephalic nucleus of CN V sense?

Answer 9

proprioception, spindles in mm of mastication, mechanoreceptors in gums, teeth and hard palate

Question 10

What are the proprioception receptors of the mesencephalic nucleus?

Answer 10

• neuromuscular spindles of mastication mm

- pressure/tension receptors in periodontal ligaments

Question 11

What does proprioception part of mesencephalic nucleus control?

Answer 11

distance between mandible and maxilla (occlusal vertical dimension)

Question 12

Which brodmann’s areas are the cortical representation of CN V?

Answer 12

3, 1, 2

Question 13

What does the main sensory nucleus of CN V serve?

Answer 13

face, head, oral cavity, teeth, meninges

Question 14

Where does the main sensory nucleus of CN V terminate?

Answer 14

main/principal trigeminal sensory nucleus - discriminative touch and vibration

Question 15

What is the main sensory nucleus of CN V a homologue of?

Answer 15

posterior column nuclei

Question 16

What are the two ascending pathways of main sensory nucleus of CN V?

Answer 16

crossed pathway that joins DCML on way to VPM and uncrosses (dorsal trigeminal tract) inside of mouth represented to VPM

Question 17

What does the spinal trigeminal nucleus of CN V serve?

Answer 17

face, oral cavity, teeth and meninges

Question 18

Where does the spinal trigeminal nucleus terminate?

Answer 18

trigeminal spinal nucleus - pain, crude touch and temp

Question 19

Where are the cell bodies of spinal trigemnical nucleus of CN V?

Answer 19

trigeminal ganglion

Question 20

Where do afferent descend of the spinal trigeminal tract?

Answer 20

thru spinal trigmenial tract and synapse in caudal nucleus

- second order neurons send axons across midline that ascend and join STT, terminate in VPM

Question 21

Which sensory systems of CN V are myelinated?

Answer 21

mesencephalic nucleus and main sensory nucleus are heavily myelinated while the spinal nucleus is lightly myelinated

Question 22

What is the homologue of the spinal nucleus?

Answer 22

STT

Question 23

Which ascending CN V projections are bilateral and contralateral?

Answer 23

spinal nucleus = contralateral projection

main trigeminal sensory nucleus = bilateral

Question 24

What does the pars caudal blend with?

Answer 24

posterior horn of cervical cord

Question 25

3 parts of spinal trigeminal nucleus

Answer 25

pars oralis, pars interpolaris, pars caudalis

Question 26

What is the somatotopic organization of pars caudal?

Answer 26

inverted representation of face; onion peel | - primarily pain fibers

Question 27

What does substantial gelatinous contain?

Answer 27

excitatory and inhibitory interneurons | - receives raphe spinal tract fibers (serotonin)

Question 28

Where do afferent fibers come from to the pars caudalis?

Answer 28

CN VII, IX, X - for area near ear

Question 29

Arrangement of pain and temp afferents in spinal trigeminal nucleus

Answer 29

``` mand = dorsal ophthalmic = ventral maxillary = between fibers from center face end near obex fibers from back of face end in upper cervical cord ```

Question 30

Where are dried episodes of pain in distribution of one division of CN V originate from?

Answer 30

mand division = 70% | ophthalmic = <5%

Question 31

Treatment of trigemnial neuralgia. Result?

Answer 31

cutting nerve root, introducing lesion in trigeminal ganglion Result = loss of all tactile sensation

Question 32

What occurs when afferents are removed to the caudal nucleus?

Answer 32

tactile sensation is intact but pain sensation to over half of face is lost

Question 33

Which artery is most frequently involved in trigeminal neuralgia due to vascular cause?

Answer 33

branches of superior cerebellar a

Question 34

Where does CN VII provide motor innervation?

Answer 34

mm of facial expression, stapedius m

Question 35

Where does CN VII provide sensory innervation?

Answer 35

skin of outer ear (geniculate ganglion), palatine tonsil and posterior nasal cavity

Question 36

What are the actions of CN VII other than sensory and motor?

Answer 36

taste, salivation, lacrimation (lubricates cornea)

Question 37

Where do fibers from CN VII enter for the skin and outer ear?

Answer 37

spinal trigeminal tract and act exactly as trigeminal afferents

Question 38

Which motor neurons of CN VII innervate contra laterally and bilaterally?

Answer 38

lower face mm = contralateral cortex | upper face mm = bilaterally

Question 39

What does unilateral damage to corticobulbar pathway result in?

Answer 39

inability to smile or bare teeth symmetrically but ability to wrinkle forehead is unaffected

Question 40

Bell's palsy symptoms

Answer 40

paresis of facial mm, irritation of cornea, hyperacusis (stapedius), reduced lacrimation and salivation

Question 41

Where does the afferent limb go in the corneal blink reflex? efferent limb?

Answer 41

- V1 to spinal V tracy | - VII elicited by bilateral projection from spinal V nuclues/RF

Question 42

What type of felafel is the jaw jerk?

Answer 42

monosynaptic reflex

Question 43

Where do the afferent limbs extend in the jaw jerk reflex? Efferent limb?

Answer 43

- mesencephalic V neuron innervating masseter spindle | - V motor neuron

Question 44

What do olfactory receptors of the tongue respond to?

Answer 44

food vapors

Question 45

What is flavor of the tongue due to?

Answer 45

chemosensitive and somatosensory free n endings of V (IX and X) in mucus membranes of oral cavity

Question 46

What accounts for the large variations in taste among people?

Answer 46

number of papillae and taste buds and amount of taste buds in fungiform papillae

Question 47

What afferents reach the nucleus in taste pathways vis solitary tract?

Answer 47

gustatory afferents

Question 48

What do second order fibers of taste pathways do?

Answer 48

- reflex activities (swallowing and salivation) | - project uncrossed to thalamus (VPM), then to gustatory cortex (insula, medial surface or frontal operculum)

Question 49

Where does gustatory cortex project?

Answer 49

orbitofrontal cortex -> integrated with olfactory info -> amygdala -> limbic system and hypothatlamus