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neuroanatomy 2021 > Lecture 6: Brainstem and Cranial nerves (II) > Flashcards

Lecture 6: Brainstem and Cranial nerves (II) Flashcards

1
Q

Visual pathway flow

A

Starts at the retina and the ret4inal ganglion cells go back and form the optic nerve and then some of the axons cross over and some don’t, where the cross over occurs is called the optic chiasma, and then they keep going back as the optic tract and innervate various structures like the superior colliculus and the lateral geniculate nucleus of the thalamus, then the axons from the lateral geniculate nucleus go back to the visual cortex which is the overall pathway, also have the superior colliculus pathway which shows how these axons go to various motor nuclei

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2
Q

Damage at the optic chiasm (cross over) causes …

A

Bitemporal hemianopsia - peripheral vison loss, nasal retina on each side damaged, the nasal retinas see the temporal visual fields, pituitary tumour or hypothalamus tumour can put pressure on the optic chiasm and cause this

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3
Q

Optic nerve

A

axons of the retinal ganglion cells

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4
Q

Optic chiasm

A

fibers originated from nasal retina cross over to the opposite side

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5
Q

Optic tract

A

contains crossed axons from nasal retina & uncrossed axons from temporal retina

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6
Q

Lateral geniculate nucleus of the thalamus

A

processes & relays visual information to visual cortex

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7
Q

Superior colliculus

A

visual reflex centres controlling the extrinsic eye muscles

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8
Q

Primary visual cortex (occipital lobe)

A
  • processes basic visual information (contrast information & object orientation)
  • conscious perception of visual images
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9
Q

Visual association ateas (occipital lobe)

A

processes visual information concerned with shape, colour & movement

next to primary visual cortex

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10
Q

Complex visual processing - ventral parts of temporal lobe

A

identify objects in the visual field (what)

ventral stream

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11
Q

Complex visual processing - parietal cortex

A

assess the spatial location of objects (where)

dorsal stream

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12
Q

Complex visual processing - frontal cortex

A

uses visual information to guide movement

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13
Q

Oculomotor nerves location

A

Cranial nerve III

Axons extend from ventral midbrain, goes forward & passes through the superior orbital fissure to the eye

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14
Q

Oculomotor nerves composition overall

A

Mixed nerves - chiefly motor

Somatic motor axons
Parasympathetic (autonomic) motor axons
Sensory (proprioceptor) afferents

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15
Q

Oculomotor nerves composition - Somatic motor axons

A

to four of the six extrinsic (muscles on the outside of the eye) eye muscles (inferior oblique muscle and superior, inferior and medial rectus muscles)

  • move eyeball
  • to levator palpebrae superior muscle - raising upper eyelid
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16
Q

Oculomotor nerves composition -Parasympathetic (autonomic) motor axons

A
  • to constrictor muscles of iris (coloured part of the eye)- causing pupil to constrict
  • to ciliary muscle –controlling shape of lens for visual focusing
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17
Q

Oculomotor nerves composition - Sensory (proprioceptor) afferents

A

information from the PNS to CS - information communicated from the eye muscles to the midbrain

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18
Q

Oculomotor nerves known as the …

A

eye mover

Provide most of the movement of each eye
Also - opening of eyelid, constriction of pupil, focusing

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19
Q

Damage to oculomotor nerves

A

Damage causes drooping upper eyelid, dilated pupil, double vision, difficulty focusing & inability to move eye in certain directions

muscles its innervating are affected

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20
Q

Trochlear nerves location

A

Cranial nerve IV

Axons emerge from dorsal midbrain, course ventrally around midbrain, pass through the superior orbital fissure to the eye
**Only cranial nerve emerging from dorsal brainstem

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21
Q

What cranial nerve is the only one to emerge from the dorsal brainstem?

A

Trochlear nerve (4th cranial nerve)

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22
Q

Trochlear nerve composisotn

A

primarily motor (chiefly motor)

Supply somatic motor axons to (& carry proprioceptor axons from) the superior oblique muscle (which rotates the eye downward & laterally) [SO4 - superior oblique muscle innervated by the 4th cranial nerve]

  • This muscle has a tendon that hooks around a pulley called a trochlea
  • Provide eye movement
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23
Q

Trochlear nerve damage

A

Damage causes double vision & inability to rotate eye inferolaterally

double vision because not all muscles are working together to get clear vision

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24
Q

Trigeminal nerve location

A

cranial nerve V

3 major branches - ophthalmic division (VI), maxillary division (V2) and mandibular division (V3), one on each side

Axons extend from face to pons (S - sensory = large component) & pons to muscles (M - motor = small component)

Cell bodies of sensory neurons are located in large
trigeminal ganglion

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25
Q

Divisons of the trigeminal nerve

A

3 major branches - ophthalmic division (VI), maxillary division (V2) and mandibular division (V3)

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26
Q

Opthalamic division (V1) of trigeminal nerve

A

Axons run from face to pons via superior orbital fissure

Convey sensory impulses from skin of anterior scalp, upper eyelid & nose, & from nasal cavity mucosa, cornea & lacrimal (tear) gland - all of the sensory information from these structures is going to the pons via the superior orbital fissure

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27
Q

Maxillary division (V2) of trigeminal nerve

A

Axons run from face to pons via foramen rotundum

Convey sensory impulses from nasal cavity mucosa, palate, upper teeth, skin of cheek and upper lip

anaesthetised when getting upper teeth dental work

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28
Q

Mandibular division (V3) of trigeminal nerve

A

Axons pass through skull via foramen ovale

Convey sensory (pain, temp (hot and cold) but not taste from the tongue) impulses from anterior tongue (except taste buds), lower teeth, skin of chin, & temporal region of scalp

V3 has a motor branch - Supply motor axons to (carry proprioceptor axons from) muscles of mastication (chewing muscles)

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29
Q

Trigeminal nerve composition

A

Mixed nerves - mainly sensory

  • Largest cranial nerves
  • Main sensory nerve from face (transmitting afferent impulses from touch, temperature & pain receptors)
  • Supply motor axons to muscles of mastication (V3)

Part of each nerve can be anaesthetised during dental procedures

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30
Q

Trigeminal nerve damage

A

Damage produces loss of sensation & impaired

chewing

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31
Q

Tic Douloureux (trigeminal neuralgia)

A
  • inflammation of trigeminal nerve (pressure on nerve root)
  • excruciating pain
  • provoked by a sensory stimulus in area of supply (touching forehead for example)
  • analgesics - partially effective
  • Nerve cut in severe case to relieve pain (but causing sensation loss)
32
Q

Abducens nerve location

A

Cranial nerve VI

Axons leave inferior pons & pass through superior orbital fissure to eye (lateral rectus muscle)

33
Q

Abducens nerve function

A

Provide eye movement (abducts the eyeball - i.e. moves it from the midline )

34
Q

Abducens nerve damage

A

Damage results in inability to rotate eye laterally & at rest eye rotates medially (lazy eye)

35
Q

Facial nerves location

A

Cranial nerve VII

Axons emerge from pons, enter temporal bone via internal auditory meatus and run within bone (bony canal) (through inner ear cavity) before emerging through stylomastoid foramen; course to lateral aspect of face

36
Q

Branches of the facial nerves from most superior to inferior

A 
temporal 
zygomatic 
buccal (cheek)
mandibular (mandible/jaw)
cervical (neck)
37
Q

Mandibular branches for both

A

trigeminal and facial nerves (do not get confused between the two)

38
Q

Facial nerves composition

A

Mixed nerves

Major motor axons of face

  • Supply motor axons to (convey proprioceptor impulses from) skeletal muscles of face (muscles of facial expression), except for chewing muscles served by cranial nerve V (trigeminal supplies this instead)
  • Transmit parasympathetic (autonomic) motor impulses to lacrimal (tear) glands, nasal & salivary glands
  • Convey sensory impulses from taste buds of anterior 2/3 of tongue - taste from anterior part of tongue through this nerve
39
Q

Facial nerves damage

A

Damage produces sagging facial muscles & disturbed sense of taste (missing sweet, salty & umami)

40
Q

Bells Palsy

A

facial nerve damage
usually unilateral not bilateral

characterised by paralysis of facial muscles (affected
side) & partial loss of taste sensation (because the facial nerve is not responsible for all of the taste information)

  • viral infection causing inflammation of facial nerve
  • symptoms: lower eyelid droops, corner of mouth sags, tears drip continuously, eye cannot be completely closed, paralysed face is ‘pulled’(to the other side). Treatment: steroids, rest
41
Q

Vestibulocochlear nerve location

A

Cranial nerve 8

Axons arising from hearing & equilibrium apparatus (which is the cochlea and the semicircular canals) within inner ear of temporal bone, passing through internal acoustic meatus to enter brainstem at the pons- medulla border

more laterally arising than the facial nerves on the pons - medulla junction/inferior part of pons

42
Q

Vestibulocochlear nerve composition

A

Purely sensory

Provide hearing (cochlea nerves) and sense of balance (vestibular nerves)

43
Q

Vestibulocochlear nerve damage

A

Damage produces deafness, dizziness,

nausea, loss of balance and nystagmus (rapid involuntary eye movements)

44
Q

Auditory pathway

A

Pathway from the sensory receptors to the brain …. Stimulation of an inner hair cell in the cochlea which generates an action potential which runs down the vestibulocochlear nerve and then it follows a pathway innervating various collections of nerves (don’t need to know names of the pathway just appreciate there is one), so the action potential runs in the vestibulocochlear nerve to the cochlear nucleus of that nerve then in turn these neurons innervate the superior olivary nucleus which then goes and innervates the inferior colliculus which we know is a part of the auditory pathway and it crosses to the other side here and then from the inferior colliculus information is conducted up to the thalamus but now to the medial geniculate body and from here it goes up to the primary auditory cortex and another name for this is the transverse temporal gurus

45
Q

Glossopharyngeal nerves location

A

Cranial nerve 9

Axons emerge from medulla & leave skull through jugular foramen - it is the first nerve that emerges from the medulla

46
Q

Glossopharyngeal nerves composition

A

Mixed nerves with sensory and motor component

47
Q

Glossopharyngeal nerves function

A

• Supply motor axons to (carry proprioceptor fibers from) a pharyngeal muscle - stylopharyngeus (skeletal muscle)
• Provide parasympathetic motor axons to parotid
salivary gland (smooth muscle)

  • Sensory axons conduct taste & general sensory impulses from pharynx & posterior 1/3 of tongue
  • Conducting sensory impulses from chemoreceptors (detect oxygen levels and determine whether you are hypoxic or not) in the carotid body & pressure receptors of carotid sinus

Provide control over swallowing, salivation, gagging, sensations from posterior 1/3 of tongue, control of blood pressure & respiration

48
Q

Glosspharyneal nerve damage

A

Damage results in loss of bitter & sour taste, and impaired swallowing

49
Q

Vagus nerve location

A

Cranial nerve 10

Axons emerge from medulla, pass through skull via jugular foramen, descend through neck region into
thorax & abdomen

50
Q

Vagus nerve composition

A

mixed nerve

motor
Supply motor axons to (carry proprioceptor fibers from) skeletal muscles of pharynx & larynx
- Parasympathetic motor fibers supply heart, lungs & abdominal viscera

sensory axons
conducting sensory impulses from thoracic &
abdominal viscera
- transmitting sensory impulses from chemoreceptors in the carotid & aortic bodies, & pressure receptors of carotid sinus
- conducting sensory impulses from taste buds of posterior tongue & pharynx

51
Q

Vagus nerve is the only cranial nerve to do what

A

The only cranial nerve extending beyond the head &

neck to the thorax & abdomen

52
Q

Majority of vagus nerve motor axons are

A

Majority of motor axons are parasympathetic

53
Q

Overall function of vagus nerve

A

Provide swallowing & speech;

• regulate activities of major viscera

54
Q

Vagus nerve damage

A

Damage causes hoarseness or loss of voice, impaired swallowing & digestive system mobility
Fatal if both are cut - critical for heart and lungs to maintain function

55
Q

Accessory nerves location

A

Cranial nerve 11
Accessory to vagus nerve

Cranial root (lateral medulla) - through jugular foramen - joins vagus nerve (X)

Spinal root (spinal C1-C5) - through foramen magnum - to neck muscles

56
Q

Cranial root of accessory nerves

A

Cranial root joins with axons of vagus nerve (X) to supply motor axons to larynx, pharynx & soft palate

57
Q

Accessory nerve composition

A

mixed nerves - primarily motor

58
Q

Damage to cranial root of accessory nerves

A

Damage causes hoarseness or loss of voice & impaired swallowing

59
Q

Spinal root of accessory nerves

A

Spinal root supplies motor axons to (conveys proprioceptor impulses from) trapezius &
sternocleidomastoid muscles, therefore provides head, neck & shoulder movement

60
Q

Damage to spinal root of accessory nerves

A

Damage causes impaired head, neck & shoulder movement. eg. unable to shrug on one side if unilateral injury

61
Q

Hypoglossal nerves location

A

(below tongue)
Cranial nerve 12

  • Axons arise by a series of roots from medulla, exit from skull via hypoglossal canal to tongue
  • Axons emerge between the pyramid & olive
62
Q

Hypoglossal nerves composition

A

primarily motor

Supply somatic motor axons to (convey proprioceptor impulses from) intrinsic & extrinsic muscles of tongue

Provide tongue movements of speech, food manipulation & swallowing

63
Q

Damage to hypoglosaal nerves

A

Damage causes difficulties in speech & swallowing Both sides - inability to protrude tongue
One side - tongue deviates (leans) towards injured side & results in ipsilateral atrophy eventually

64
Q

Olfactory - sensory function? motor function? parasympathetic fibres?

A

yes (smell)
No
No

65
Q

Optic - sensory function? motor function? parasympathetic fibres?

A

yes (vision)
No
No

66
Q

Oculomotor - sensory function? motor function? parasympathetic fibres?

A

No
Yes
Yes

67
Q

Trochlear - sensory function? motor function? parasympathetic fibres?

A

No
Yes
No

68
Q

Trigeminal - sensory function? motor function? parasympathetic fibres?

A

Yes (general sensation)
Yes
No

69
Q

Abducens - sensory function? motor function? parasympathetic fibres?

A

No
Yes
No

70
Q

Facial - sensory function? motor function? parasympathetic fibres?

A

Yes (taste)
Yes
Yes

71
Q

Vestibulocochlear - sensory function? motor function? parasympathetic fibres?

A

Yes (hearing and balance)
No
No

72
Q

Glossopharyngeal - sensory function? motor function? parasympathetic fibres?

A

Yes (taste)
Yes
Yes

73
Q

Vagus - sensory function? motor function? parasympathetic fibres?

A

yes (taste)
Yes
Yes

74
Q

Accessory - sensory function? motor function? parasympathetic fibres?

A

No
yes
No

75
Q

Hypoglossal - sensory function? motor function? parasympathetic fibres?

A

No
yes
no

76
Q

Reticular formation

A

DO NOT FORGET TO DO THE LAST FEW SLIDES OF THIS LECTURE !!!!

neuroanatomy 2021 (32 decks)

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