CN V and VII Flashcards
1
Q
fnctns of V
A
transmits tactile, proprioceptive, pain and temp from head to cortex (also cerebellum and RF)
2
Q
divisions of CN V
A
- opthalmic: upper face, sensory only
- maxillary: middle face, sensory only
- mandibular: lower face, sensory and motor
3
Q
functional components of CN V
A
mesencephalic nucleus, main/principle nucleus, spinal nucleus, motor nucleus
4
Q
motor components of CN V
A
- brachial motor
- cell bodies: trigeminal motor nucleus (terminate in MOM and TT) *lesion causes weakened jaw closure, open jaw deviating to side of lesion
5
Q
supratrigeminal nucleus
A
- near V motor nucleus, actually part of RF
- pattern generator for masticatory rhythm
6
Q
CN V motor nucleus
A
- innervates MOM and TT
- brachial motor nucleus (1st arch mm)
- efferent limb of jerk reflex
7
Q
CN V mesencephalic nucleus
A
- sensory afferent
- cell bodies: trigeminal nesencephalic nucleus, centrally directed process terminate in 1. trigem motor nucleus (jaw jerk reflex) 2. supratrigem nucleus (chewing)
- senses: proprioception (spindles in MOM, mechanoreceptors in gums, teeth, and hard palate)
8
Q
proprioception from CN V
A
- receptors: neuromuscular spindles of MOM, pressure/tension receptors in periodontal ligs
- cell body of origin: unipolar, trigem mesencephalic nucleus
- projects to: trigem motor nucleus, supratrigem nucleus controls occlusal vert dimension
9
Q
sensory components of CN V
A
- trigem main/princliple sensory nucleus: mid pons (forms column of cells almost continuous thru BS)
- trigem spinal nucleus: extends caudally into medulla
10
Q
cortical representation of CN V
A
parietal lobe (post central gyrus, brodmanns area (3-1-2)
11
Q
main sensory nucleus of CN V
A
- sensory afferent service face, head, oral cavity, teeth, meninges
- cell bodies: trigem ganglion
- terminate in main/princliple trigem sensory nucleus (discriminative touch and vibration, proprioception)
12
Q
2 ascending pathways of mean sensory nucleus of CN V
A
- crossed joins medial lemn on way to VPM
2. uncrossed (dorsal trigem tract) inside mouth represented to VPM)
13
Q
spinal trigeminal nucleus of CN V
A
- sensory afferent service face, oral cavity, teeth meninges
- cell bodies: trigeminal ganglion
- term in trigem spinal nucleus (pain, crude touch, temp)
14
Q
path of spinal trigeminal nucleus of CN V
A
- afferents descend thru spinal trigem tract and synapse in caudal nucleus
- 2nd order neurson send axons across midline, ascend and join spinothalamic tract, terminate in VPM
- pars oralis/interpolaris: crude touch
- pars caudalis: pain and temp mediated
15
Q
CN V major connections
A
- peripheral brs of mesencephalic neurons innervate messeter m spindle and other mechanoreceptors
- tactile afferents
- motor neuron fibers: MOM
- pain/temp afferents
16
Q
injury to pars caudalis
A
- causes inverted representation of face
- “onion peel” rostral (oral) to caudal (peripheral)
- primarily pain fibers
- more caudal the injury the larger area around mouth that is spared of sensory loss
17
Q
motor functions of CN VII
A
- mm of facial expression: closes eyes and lips
- stapedius m: modulates sound volume
18
Q
sensory function of CN VII
A
- skin of outer ear (geniculate ganglion)
- palatine tonsil and post nasal cavity (geniculate ganglion-solitary nucleus)
19
Q
other functions of CN VII
A
- salivation
- lacrimation
- taste: ant 2/3 tongue
20
Q
somatic sensory of CN VII
A
- skin of outer ear
- fibers enter spinal trigem tract, dorsomedially situated
- act exactly as trigeminal afferents
21
Q
facial motor nucleus and corticibulbar path
A
- motor neurons to lower facial mm mainly innervated by contralat cortex, but upper facial mm innervated bilaterally
- unilat damage results in inability to smile symmetrically but can still wrinkly forehead symmetrically
22
Q
trigeminal neuralgia
A
- brief episodes of pain in one or more div of CN VII (mainly mandibular)
- no sensory trouble btwn attacks
- often tactile stimuli is trigger
- many cases due to trigem compression by tumor or sup cerebral artery
23
Q
cures for trigem neuralgia
A
- destroying trigem gang would remove all sensation from entire side of face
- section trigem tract slightly caudal to obex, remove afferents to caudal nucleus
24
Q
Bell’s palsy
A
- unilat facial paralysis bc CN VII dysfunction
- great discomfort for denture wearers
- unknown cause, believed to be facial n swelling in canal
- commonly rapid onset w/ partial or complete paralysis
- usually improves over time and w/ steroids
25
corneal blink reflex
- touch cornea and both eyes blink
- afferent limb: Vi to SpV tract
- efferent limb: VII elicited by bilat projection from SpV nucleus/RF
- clinical test of V, VII, and central connections
26
jaw opening/closing reflex
- opening: food in contact with oral membrane
- closing: periodontal afferents activated by occlusion, pain afferents from mucosal membrane
- input (V) from
1. jaw mm (proprioception: trigem mesencephalic nucleus)
2. tactile info (food in mouth: trigem main nuc)
3. pain info: trigem spinal nuc)
- output to MOM
27
jaw jerk reflex
- monosynaptic reflex
- downward tap on chin, stretches masseter m
- aff lim: mesencephalic V neuron innervating masseter spindle
- eff limb: V motor neuron
28
what is flavor due to?
1. direct chemical stimulation
2. olfactory receptors responding to food vapors
3. chemosensitive and somatosensory free n endings of V, IX, and X in mucous mem
29
where does taste input go?
to rostral aspect of nucleus of solitary tract
30
taste pathway in CNS
-gustatory afferents reach nucleus of the solitary tract via the solitary tract
31
what do 2nd order fibers do in the taste pathway?
1. reflex activities: swallow, salivate
2. project uncrossed to thalamus (VPM), then to gustatory cortex (insula)
*projects to orbitofrontal cortex, integrated there w/ olfactory info, reches amygdala, then to limbic system and hypothalamus
