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Cranial Nerves (Ch 15) Flashcards

1
Q

Cranial Nerve Summary

A
  • part of PNS

- sensory, motor, and parasympathetic nerve fibers that innervate the HEAD and VISCERA

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2
Q

Where do cranial nerve originate?

A

brain and brainstem

  • olfactory/optic attach to forebrain
  • only vagus extends past head/neck
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3
Q

How many pairs of cranial nerves are there?

A

12

  • 3 pairs of sensory nerves
  • 5 pairs of motor nerves
  • 4 pairs of mixed nerves
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4
Q

Cranial Nerve List

A 
CN 1: Olfactory
CN 2: Optic
CN 3: Oculomotor
CN 4: Trochlear
CN 5: Trigeminal
CN 6: Abducens
CN 7: Facial
CN 8: Vestibulocochlear
CN 9: Glossopharyngeal
CN 10: Vagus
CN 11: Spinal Accessory
CN 12: Hypoglossal
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5
Q

Mnemonic for remembering the order of cranial nerves

A

On On On They Traveled And Found Voldemort Guarding Very Secret Horcruxes

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6
Q

What are the Sensory Cranial Nerves?

A

–> innervate for special sensory structures (smell, vision, equilibrium, and hearing)
CN 1: Olfactory Nerve
CN 2: Optic Nerve
CN 8: Vestibulocochlear

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7
Q

Olfactory Nerve

A

CN 1

sensory: olfaction (smell)
origin: olfactory epithelium of nose (terminate in post olfactory cortex)

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8
Q

Optic Nerve

A

CN 2

  • -> not technically a nerve, but a brain tract
    sensory: vision
    origin: retina of eye (terminate in primary visual cortex)
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9
Q

Vestibulocochlear Nerve

A

CN 8

sensory: hearing and balance (equilibrium)
origin: inner ear, enters brainstem at pons

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10
Q

What are the Motor Cranial Nerves?

A 
--> somatic motor fibers to skeletal muscles of eye, neck/back, and tongue
CN 3: Oculomotor
CN 4: Trochlear
CN 6: Abducens
CN 11: Spinal Accessory Nerve
CN 12: Hypoglossal
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11
Q

Oculomotor Nerve

A

CN 3

motor: extrinsic eye muscle
origin: midbrain
- -> also parasympathetic

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12
Q

Trochlear Nerve

A

CN 4

motor: extrinsic eye muscle
origin: midbrain

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13
Q

Abducens Nerve

A

CN 6

motor: extrinsic eye muscles
origin: pons

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14
Q

Spinal Accessory Nerve

A

CN 11

motor: innervates trapezius + sternocleidomastoid muscle
origin: rootlets at cervical region of spinal cord

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15
Q

Hypoglossal Nerve

A

CN 12

motor: tongue muscles
origin: medulla oblongata

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16
Q

What are the conditions of damaged eye innervation?

A

Strabismus (eyes not parallel)
Ptosis (drooping eyelids)
Diplopia (double vision)

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17
Q

What are the Mixed Cranial Nerves?

A
  • -> sensory innervation of the face, mouth, viscera
  • -> motor innervation to pharyngeal arch muscles (chewing/facial expression)

CN 5: Trigeminal
CN 7: Facial
CN 9: Glossopharyngeal
CN 10: Vagus

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18
Q

Trigeminal Nerve

A

Three Branches:
V1- ophthalmic
V2- maxillary
V3- mandibular

motor: V1 only, muscles of mastication
sensory: V1/V2/V3, somatic sensory for face, oral cavity, nasal cavity, anterior 2/3 of tongue (not taste)
origin: sensory receptor to pons

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19
Q

Facial Nerve

A

CN 7
somatic motor: muscles of facial expression

visceral motor: parasympathetic, lacrimal glands (tears), submandibular/sublingual salivary glands (digestion), and nasal/palatine glands

sensory: taste, anterior 2/3 of tongue, small patch at ear for somatic sensory
origin: medulla oblongata (posterior 1/3 of tongue)

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20
Q

Vagus Nerve

A

CN 10
somatic motor: larynx/pharyngeal muscles

visceral motor: parasympathetic, thoracolumbar viscera through 2/3 of intestines (regulates HR, breathing, digestive system)

sensory: external auditory meatus and laryngopharynx, also visceral sensory from most thoracoabdominal viscera
- -> mostly visceral sensory

origin: medulla oblongata
a. k.a. “the wanderer” - only cranial nerve to extend beyond head/neck

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21
Q

What are the Visceral Motor Nerves?

A

CN 3: Oculomotor - pupils
CN 7: Facial - lacrimal/salivary glands
CN 9: Glossopharyngeal - salivary glands (parotid)
CN 10: Vagus - thoracoabdominal organs

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22
Q

What are the three main parts of the ear?

A

External, Middle, and Inner Ear

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23
Q

External Ear

A
  • auricle gathers sound waves and funnels into external auditory meatus
  • mostly elastic cartilage
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24
Q

External Acoustic Meatus

A

short tube running from auricle to eardrum, lined with hairs, sebaceous glands, and ceremonious glands to keep dust/insects out

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25
Tympanic Membrane
a. k.a. eardrum - boundary between external and middle ear - sound waves entering EAM hits eardrum, causes vibration
26
Middle Ear
- air filled space medial to eardrum - located inside petrous part of temporal bone - holes in bony wall between middle and inner ear = round and oval window
27
Middle Ear Ossicles
1. Malleus 2. Incus 3. Stapes - -> smallest bones in body - transmit vibrations from eardrum across middle ear cavity and to inner ear (eardrum vibrates against malleus, stapes vibrates against oval window)
28
What are the two muscles of the middle ear?
1. Tensor Tympani: attached to malleus | 2. Stapedius: attached to stapes
29
Pharyngotympanic Tube
a. k.a. Auditory Meatus | - -> connects middle ear to pharynx --> allows equalization of pressure on both sides of tympanic membrane
30
Otitis Media
"ear infection" - infection from throat (via pharyngotympanic tube) - fluid buildup
31
Inner Ear
a.k.a. Labyrinth Two parts: 1. Bony Labyrinth: cavity consisting of semicircular canals, vestibule, and cochlea 2. Membranous Labyrinth: walls/sacs within the bony labyrinth
32
What are the three parts of the inner ear?
1. Cochlea (hearing) 2. Vestibule (equilibrium/acceleration) 3. Semicircular Canals (equilibrium/rotation)
33
Cochlea
* hearing - looks like snail shell - cochlear nerve: runs through center of modulus (axis of cochlea (part of vestibulocochlear nerve)
34
Cochlear Duct
part of membranous labyrinth of inner ear consisting of sensory receptors for hearing roof: vestibular membrane floor: basilar membrane
35
Basilar membrane
floor of cochlea | -supports spiral organ (organ of Corti)
36
Spiral Organ
-has hair cells (cilia) --> when basilar membrane moves, cilia bend/distort --> triggers impulses
37
Vestibule
- has a utricle and saccule (expansions of labyrinth) - -> these have maculae: when head tilts, otoliths (small crystals) embedded in gelatinous layer of maculae move, and hairs bend) * sense of balance when nodding
38
Semicircular Canal
are at right angle from each other - expansion at end of ampulla (receptor for movement) - when head rotates, endolymph in canals move, cupola within ampulla bends, triggering cilia * sense of balance when rotating head
39
Vision
dominant sense in humans - 70% of sensory receptors are in eyes - 40% of cerebral cortex devoted to processing visual info
40
What are the four cranial nerves that affect vision?
CN 2: Optic CN 3: Oculomotor CN 4: Trochlear CN 6: Abducens
41
What are the external structures of the eye?
- superior/inferior palpebrum (eyelid) - lateral/medial angles - lacrimal caruncle - eyelashes
42
Conjunctiva
mucus membrane covering inner eyelids and sclera (not the cornea) Two Types: palpebrum and ocular conjunctiva
43
Lacrimal Apparatus
- lacrimal glands supply eyes with lacrimal fluid (tears) - lacrimal fluid has immune functions (mucus, antibodies, and enzymes) - drains into lacrimal sac and then nasolacrimal duct/nasal cavity (runny nose when crying)
44
Extrinsic Eye Muscles
1. Lateral Rectus (abducts) - CN 6 2. Medial Rectus (adducts) - CN 3 3. Superior Rectus (elevates/adducts) - CN 3 4. Inferior Rectus (depresses/adducts) - CN 3 5. Inferior Oblique (elevates/abducts) - CN 3 6. Superior Oblique (depresses/abducts) - CN 4
45
What are the layers of the eye?
1. Fibrous - sclera - cornea 2. Vascular - choroid - ciliary body/muscles - iris 3. Inner - retina - optic nerve
46
Fibrous Layer
* most external | - ->composed of sclera and cornea
47
Sclera
*fibrous layer | tough outer covering of eye (white), protects eyeball
48
Cornea
*fibrous layer continuation of sclera, transparent, allows light into the eye, acts as fixed lens for focusing -avascular, but lots of nerve endings
49
Vascular Layer
* middle layer | - ->composed of choroid, ciliary body/muscles, iris, and pupil (space)
50
Choroid
*vascular layer | heavily pigmented vascular layer, melanin helps to absorb light
51
Ciliary Body/Muscles
*vascular layer | encircle lens, control shape for precise focusing
52
Iris
*vascular layer | colored part of the eye, regulates light entering the eye
53
Pupil
*vascular layer | a space, NOT a structure --> allows light to enter eye
54
pupillary constriction
bright light --> sphincter papillae contracts (parasympathetic innervation)
55
pupillary dilation
low light --> dilator papillae contracts (sympathetic innervation)
56
Inner Layer
* innermost layer | - ->composed of retina and optic nerve
57
Retina
* inner layer - converts light to nerve impulses - photosensitive Two layers: pigmented and neural layer Composed of: - macula lutea - fovea centralis - optic disc
58
Pigmented Layer of retina
melanocytes, absorb light and keep it from scattering
59
Neural Layer of retina
nervous tissue with photoreceptive cells
60
Photoreceptor cells
rods: work best in dim light cones: work best in bright light, perceive red, blue, green (good for color vision) - -> absorption spectra overlap, so combo of stimulations of the cones = different colors
61
Macula Lutea
*in retina | area of concentrated cone cells at posterior pole
62
Fovea Centralis
* in retina - area of ONLY cone cells in center of macula lute - highest visual acuity
63
Optic Disc
* in retina - blind spot - location where optic nerve attaches - NO photoreceptor cells
64
Lens
avascular, transparent disc -shape can be changed to adjust focus Two chambers: 1. Anterior Chamber: in front of lens, has aqueous humor 2. Posterior Chamber: behind lens, has vitreous humor, most volume of eye
65
Humor
Aqueous Humor: CSF-like Vitreous Humor: jelly-like --> help maintain interocular pressure
66
Images coming into eye
lens is convex (images are upside-down and reverse) --> cerebral cortex flips image back to normal
67
Benign Paroxysmal Positional Vertigo (BPPV)
- room spinning = vertigo (not dizziness) - fluid disrupted in ear (semicircular canal) - -> Epsley Maneuver
68
Cataracts
buildup of proteins in the lens | -one of the most common causes of blindness
69
Glaucoma
increased interocular pressure that can affect the optic nerve (vision)
70
Glossopharyngeal Nerve
sensory: posterior 1/3 of tongue, general visceral sensory motor: stylopharngeus muscle (swallowing), parotid salivary gland (digestion) origin: medulla oblongata

Anatomy (25 decks)

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