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Anatomy > Cranial Nerves (Ch 15) > Flashcards

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
Q

Tympanic Membrane

A

a. k.a. eardrum
- boundary between external and middle ear
- sound waves entering EAM hits eardrum, causes vibration

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26
Q

Middle Ear

A
  • 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
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27
Q

Middle Ear Ossicles

A
  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)
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28
Q

What are the two muscles of the middle ear?

A
  1. Tensor Tympani: attached to malleus

2. Stapedius: attached to stapes

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29
Q

Pharyngotympanic Tube

A

a. k.a. Auditory Meatus

- -> connects middle ear to pharynx –> allows equalization of pressure on both sides of tympanic membrane

30
Q

Otitis Media

A

“ear infection”

  • infection from throat (via pharyngotympanic tube)
  • fluid buildup
31
Q

Inner Ear

A

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
Q

What are the three parts of the inner ear?

A
  1. Cochlea (hearing)
  2. Vestibule (equilibrium/acceleration)
  3. Semicircular Canals (equilibrium/rotation)
33
Q

Cochlea

A
  • hearing
  • looks like snail shell
  • cochlear nerve: runs through center of modulus (axis of cochlea (part of vestibulocochlear nerve)
34
Q

Cochlear Duct

A

part of membranous labyrinth of inner ear consisting of sensory receptors for hearing

roof: vestibular membrane
floor: basilar membrane

35
Q

Basilar membrane

A

floor of cochlea

-supports spiral organ (organ of Corti)

36
Q

Spiral Organ

A

-has hair cells (cilia) –> when basilar membrane moves, cilia bend/distort –> triggers impulses

37
Q

Vestibule

A
  • 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
Q

Semicircular Canal

A

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
Q

Vision

A

dominant sense in humans

  • 70% of sensory receptors are in eyes
  • 40% of cerebral cortex devoted to processing visual info
40
Q

What are the four cranial nerves that affect vision?

A

CN 2: Optic
CN 3: Oculomotor
CN 4: Trochlear
CN 6: Abducens

41
Q

What are the external structures of the eye?

A
  • superior/inferior palpebrum (eyelid)
  • lateral/medial angles
  • lacrimal caruncle
  • eyelashes
42
Q

Conjunctiva

A

mucus membrane covering inner eyelids and sclera (not the cornea)
Two Types: palpebrum and ocular conjunctiva

43
Q

Lacrimal Apparatus

A
  • 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
Q

Extrinsic Eye Muscles

A
  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
Q

What are the layers of the eye?

A
  1. Fibrous
    - sclera
    - cornea
  2. Vascular
    - choroid
    - ciliary body/muscles
    - iris
  3. Inner
    - retina
    - optic nerve
46
Q

Fibrous Layer

A
  • most external

- ->composed of sclera and cornea

47
Q

Sclera

A

*fibrous layer

tough outer covering of eye (white), protects eyeball

48
Q

Cornea

A

*fibrous layer
continuation of sclera, transparent, allows light into the eye, acts as fixed lens for focusing
-avascular, but lots of nerve endings

49
Q

Vascular Layer

A
  • middle layer

- ->composed of choroid, ciliary body/muscles, iris, and pupil (space)

50
Q

Choroid

A

*vascular layer

heavily pigmented vascular layer, melanin helps to absorb light

51
Q

Ciliary Body/Muscles

A

*vascular layer

encircle lens, control shape for precise focusing

52
Q

Iris

A

*vascular layer

colored part of the eye, regulates light entering the eye

53
Q

Pupil

A

*vascular layer

a space, NOT a structure –> allows light to enter eye

54
Q

pupillary constriction

A

bright light –> sphincter papillae contracts (parasympathetic innervation)

55
Q

pupillary dilation

A

low light –> dilator papillae contracts (sympathetic innervation)

56
Q

Inner Layer

A
  • innermost layer

- ->composed of retina and optic nerve

57
Q

Retina

A
  • inner layer
  • converts light to nerve impulses
  • photosensitive

Two layers: pigmented and neural layer

Composed of:

  • macula lutea
  • fovea centralis
  • optic disc
58
Q

Pigmented Layer of retina

A

melanocytes, absorb light and keep it from scattering

59
Q

Neural Layer of retina

A

nervous tissue with photoreceptive cells

60
Q

Photoreceptor cells

A

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
Q

Macula Lutea

A

*in retina

area of concentrated cone cells at posterior pole

62
Q

Fovea Centralis

A
  • in retina
  • area of ONLY cone cells in center of macula lute
  • highest visual acuity
63
Q

Optic Disc

A
  • in retina
  • blind spot
  • location where optic nerve attaches
  • NO photoreceptor cells
64
Q

Lens

A

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
Q

Humor

A

Aqueous Humor: CSF-like
Vitreous Humor: jelly-like
–> help maintain interocular pressure

66
Q

Images coming into eye

A

lens is convex (images are upside-down and reverse) –> cerebral cortex flips image back to normal

67
Q

Benign Paroxysmal Positional Vertigo (BPPV)

A
  • room spinning = vertigo (not dizziness)
  • fluid disrupted in ear (semicircular canal)
  • -> Epsley Maneuver
68
Q

Cataracts

A

buildup of proteins in the lens

-one of the most common causes of blindness

69
Q

Glaucoma

A

increased interocular pressure that can affect the optic nerve (vision)

70
Q

Glossopharyngeal Nerve

A

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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