Cranial Nerves Part 2 Flashcards Preview

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Flashcards in Cranial Nerves Part 2 Deck (39)
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1
Q

What types of neurons make up CN 5?

A
  1. somatosensory → from skin, muscle, and joint conscious sensory receptors of anterior 2/3 head
  2. somatomotor → muscles of mastication nad tensor tympani
2
Q

What are the 3 branches of the trigeminal nerve (CN 5)?

A

opthalmic

maxillary

mandibular

3
Q

what region of the head/face is the opthalmic nerve the primary sensory neuron for?

A
  1. upper face-forehead
  2. cornea
  3. upper eyelid
  4. dorsum of nose

*cutaneous sensation (touch, pressure, pain and temp) and proprioception

4
Q

what region of the head/face is the maxillary nerve the primary sensory neuron for?

A
  1. middle face-lower lip
  2. lateral nose
  3. cheek
  4. upper jaw/teeth
  5. palate
  6. upper lip
5
Q

what region of the head/face is the mandibular nerve the primamry sensory neuron for?

A
  1. lower face-lower lip
  2. lower jaw/teeth
  3. tongue
  4. chin
6
Q

what is the soma for the 3 somatosensory peripheral axons (opthalamic, maxillary, mandibular) of the trigeminal nerve?

A

trigeminal (semilunar) ganglion

7
Q

where is the trigeminal (semilunar) ganglion located?

A

base of sella turcica

close proximity to the internal carotid

8
Q

Describe the motor pathway for the Trigeminal Nerve

A
  1. R/L precentral gyrus (lateral homonculus) = UMN
  2. corticobulbar tract
  3. crossed and uncrossed bilateral input to motor nucleus trigeminal nerve = LMN
  4. trigeminal nerve
  5. 3 peripheral branches of trigeminal nerve
9
Q

what muscles are innervated by the trigeminal nerve?

A
  1. muscles of mastication
  2. mylohyoid
  3. anterior belly digastric
  4. tensor tympani
10
Q

how does the sensation of taste occur?

A

it is a result of a chemical interaction between molecules in mouth and membrane chemoreceptors on receptor cells in taste buds

11
Q

Where are taste buds located in the mouth?

A

in papillae of the:

  1. tongue
  2. soft palate (roof of mouth)
  3. pharynx (throat)
  4. larynx
12
Q

T/F: taste buds are the neuronal receptor cells for the sense of taste

A

FALSE

they are receptor cells but NOT neurons.

dendrites of cranial nerves synapse onto them

13
Q

receptors in the tip of the tongue are more sensitive to ______

A

sweet

14
Q

receptors in the posterior tongue are more sensitive to _______

A

bitter

15
Q

receptors in lateral tongue are most sensitive to _________

A

sour and salty

16
Q

T/F: we can decrease our sensitivity to particular tast stimuli?

A

TRUE

if we are continuously exposed

complete adaptation in 1-5 min of continuous stimulation

17
Q

Describe the initial steps in the gustatory pathway (from molecule to generation of AP)

A
  1. bite of food is chewed and dissolved into food molecules
  2. foot molecules dissolve in saliva
  3. food molecule binds receptor on gustatory receptor hair cell
  4. gustatory hair cell releases chemical messenger
  5. chemical messenger binds chemical gated channel on dendrite of pseudo unipolar taste neuron
  6. AP generated on peripheral process of pseudounipolar neuron of CN 7, 9, or 10
18
Q

Describe the general steps in the gustatory pathway from generation of AP to integration of sensation

A
  1. AP is generated on peripheral process of pseudounipolar neuron of CN 7, 9, or 10
  2. travels to sensory ganglia for taste (3 different ganglia)
  3. then travels into brain stem in the solitary tract
  4. synapses on secondary neurons in gustatory portion of solitary tract
  5. Tertiary neuron in VPM of thalamus
  6. tertiary neuron head to Cerebral cortex an dlimbic system for integration
19
Q

where in the cerebral cortex does taste differentiation occur?

A

insula

inferior postcentral gyrus

20
Q

what is the limbic system’s role within the taste pathway?

A

emotional response to taste

21
Q

what are the different sensory ganglia for taste?

A
  1. CN 7 → geniculate ganglia
  2. CN 9 → inferior petrosal ganglia of CN 9
  3. CN 10 → inferior (no dose) ganglia of CN 10
22
Q

CN 7 is responsible for carrying sensory info from taste receptors in what areas?

A

anterior 2/3 of tongue

23
Q

CN 9 is responsible for carrying sensory info from taste receptors in what areas?

A

posterior 1/3 of tongue

24
Q

CN 10 is responsible for carrying sensory info from taste receptors located in what areas?

A

base of tongue/pharynx

25
Q

what types of neurons make up CN 7?

A
  1. special sensory for taste (pseudo unipolar neuron)
  2. somatosensory
  3. somatic motor
  4. autonomic motor
26
Q

what is type of info is carried within the somatosensory neurons of CN 7?

A

proprioception of muscles of facial expression

skin sensation of posterior ear, external auditory meatus

27
Q

what type of info is carried within somatic motor neurons of CN 7?

A

motor efferent to muscles of facial expression, stapedius

28
Q

what type of info is carried within autonomic motor neurons of CN 7?

A

preganglionic parasympathetic input headed to lacrimal and salivary glands

29
Q

where is the primary sensory neuron soma located for the CN 7 sensory pathway?

A

geniculate ganglia within the petrous portion of temporal bone

30
Q

where is the secondary sensory neuron within the CN 7 sensory pathway?

A

spinal (trigeminal) nucleus of CN 5

31
Q

where is the tertiary sensory neuron within the CN 7 sensory pathway?

A

VPM of thalamus

32
Q

after synapsing with the tertiary neuron, where does the sensory pathway of CN 7 head?

A

contralateral postcentral gyrus

33
Q

Describe the motor pathway for CN 7

A
  1. precentral gyrus (UMN)
  2. corticobulbar tracts
  3. facial nucleus (LMN at lvl of open medulla/pons)
  4. CN 7 exits brainstem at junctin of pons and medulla
  5. CN 7 exits skull at stylomastoid foramen and divides in cutaneous nerves of partoid plexus
34
Q

what are the branches of the partoid plexus?

A
  1. auricular nerve
  2. temporal branch
  3. zygomatic branch
  4. buccal branch
  5. marginal (mandibular) branch
  6. cervical branch
35
Q

How does CN 7 innervate the stapedes muscle?

A

branch of CN 7 enters petrous portion of temporal bone through internal acoustic meatus and heads to the middle ear

somatomotor to stapedes muscle

36
Q

what types of neurons is CN 9 comprised of?

A
  1. somatosensory from posterior ear
  2. special sensory for taste
  3. visceral sensory from carotid sinus and carotid body
  4. somatomotor to stylopharngeus muscle
  5. autonomic motor to salivary glands
37
Q

what types of neurons is CN 10 comprised of?

A
  1. somatosensory from posterior ear and external auditory canal
  2. viscerosensory from thoracic and abdomen organs
    1. aortic arch baro- and chemoreceptors
  3. special sensory for taste
  4. somatomotor to pharyngeal and laryngeal muscles, and palatoglossus of tongue
  5. autonomic motor to organs of thorax and abdomen
38
Q

what types of neurons in CN 11?

A

somatomotor to SCM and trapezius muscle

39
Q

what types of neurons are in CN 12?

A

somatomotor to intrinsic and extrinsic muscles of tongue