Cranial Nerves (Ch 15) Flashcards Preview

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Flashcards in Cranial Nerves (Ch 15) Deck (70):
1

Cranial Nerve Summary

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

2

Where do cranial nerve originate?

brain and brainstem
-olfactory/optic attach to forebrain
*only vagus extends past head/neck

3

How many pairs of cranial nerves are there?

12
-3 pairs of sensory nerves
-5 pairs of motor nerves
-4 pairs of mixed nerves

4

Cranial Nerve List

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

5

Mnemonic for remembering the order of cranial nerves

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

6

What are the Sensory Cranial Nerves?

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

7

Olfactory Nerve

CN 1
sensory: olfaction (smell)
origin: olfactory epithelium of nose (terminate in post olfactory cortex)

8

Optic Nerve

CN 2
--> not technically a nerve, but a brain tract
sensory: vision
origin: retina of eye (terminate in primary visual cortex)

9

Vestibulocochlear Nerve

CN 8
sensory: hearing and balance (equilibrium)
origin: inner ear, enters brainstem at pons

10

What are the Motor Cranial Nerves?

--> 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

11

Oculomotor Nerve

CN 3
motor: extrinsic eye muscle
origin: midbrain
--> also parasympathetic

12

Trochlear Nerve

CN 4
motor: extrinsic eye muscle
origin: midbrain

13

Abducens Nerve

CN 6
motor: extrinsic eye muscles
origin: pons

14

Spinal Accessory Nerve

CN 11
motor: innervates trapezius + sternocleidomastoid muscle
origin: rootlets at cervical region of spinal cord

15

Hypoglossal Nerve

CN 12
motor: tongue muscles
origin: medulla oblongata

16

What are the conditions of damaged eye innervation?

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

17

What are the Mixed Cranial Nerves?

--> 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

18

Trigeminal Nerve

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

19

Facial Nerve

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)

20

Vagus Nerve

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

21

What are the Visceral Motor Nerves?

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

22

What are the three main parts of the ear?

External, Middle, and Inner Ear

23

External Ear

-auricle gathers sound waves and funnels into external auditory meatus
-mostly elastic cartilage

24

External Acoustic Meatus

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

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)

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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