Cranial nerves Flashcards Preview

Neurology > Cranial nerves > Flashcards

Flashcards in Cranial nerves Deck (50):
0

sensory nerves

most of their cell bodies are outside of the brain in ganglia

1

motor nerves

their cell bodies are in nuclei within the brain

2

CN 1

Olfactory nerve, sensory (smell)
Olfactory receptors (Superior part of nasal cavity, inferior surface of the cribriform plate along the superior nasal concha) ->olfactory epithelium -> olfactory nerve -> olfactory foramina in the cribriform plate -> olfactory bulbs -> olfactory tracts -> primary olfactory area 28 + limbic system + hypothalamus + habenular nuclei (Ephithalamus) emotional response to odors -> Frontal lobe #11

3

Loss of sense of smell from infections of nasal mucosa, head injuries, meningitis, smoking, cocaine use

Anosmia

4

Reduced ability to smell

hyposmia

5

increased sense of smell

hyperosmia (only sensation reach the cerebral cortex without first synapsing in the thalamus)

6

CN II

Optic Nerve (sensory nerve - optic)
Rods and cones in retina (photoreceptor->Bipolar cell -> Ganglion)
-> Optic nerves -> optic foramen (under pituitary gland) ->optic chiasm (medial half cross opposite site, lateral half does not cross) -> optic tract ->lateral geniculate nucleus in thalamus -> primary visual area #17 Occipital lobe (a few axons go to superior colliculi (tectum) in midbrain

7

cone

Stimulated in bright light, color vision, high acuity, concentrated in the center of retina

8

rod

allow us to see in dim light
no color
low acuity
concentrated in the periphery

9

Bipolar cells

lateral connections

10

Ganglion cell layer

their axons extend posteriorly to optic disc and exit the eye as the optic nerve

11

Optic disc

blind spot

12

blindness due to a defect or loss of 1 or 2 eyes

Anopia
from fractures in orbit, brain lesions, damage along the pathway disease of the nervous system, pituitary gland tumours, cerebral aneurysm

13

Make your eyes trick

CN III (Oculomotor), IV (Trochlear nerve), VI (Abducens nerve)

14

CN III

Oculomotor nerve (Motor, eye movement and upper eye lid)
Nucleus in midbrain -> superior orbital fissure -> superior branch ->superior rectus and levator palpebrae superioris
also
->inferior branch ->medial rectus, inferior rectus, inferior oblique mm

Autonomic (smooth muscle)
Motor nucleus in midbrain -> superior orbital fissure -> inferior branch -> ciliar ganglion -> ciliary muscle and circular muscle of iris

15

image formation

1. reflection n bending of light by the lens and cornea
2. Accommodation (the change in the shape of the lens) when the eye is focusing on a close object, the lens become more spherical causing greater reflection of light rays (less than 20 feet)

16

Ciliary muscle

controls the shape of lens
adjust the lens for near vision "accommodation'

17

CN IV

Trochlear nerve
Motor eye movement superior oblique (look down and out)
Smallest cranial nerve
only on the arises from the posterior brain stem
trochlear nucleus ->superior orbital fissure -> superior oblique mm of eye ball

18

CN VI

Abducens nerve (motor abducts the eye) in pons
Abducens nucleus ->superior orbital fissure -> lateral rectus muscle

19

Superior oblique muscle

makes you look down and out

20

Inferior oblique muscle

make you look up and out

21

moves the eye towards the nose

Medial rectus

22

moves eye away from the nose

lateral rectus

23

moving eye up

superior rectus

24

moves eye down

Inferior rectus

25

makes you look down and out

Superior oblique rotates

26

makes you look up and out

Inferior oblique

27

CN III eye muscles

medial rectus
superior rectus
inferior rectus
inferior oblique

28

CN IV eye muscle

Superior oblique

29

CN VI eye muscle

lateral rectus

30

Damage to occulomotor

Strabismus : lazy eye, condition in which both eyes do not fix on the same object since one or both eyes may turn inword or outword
Ptosis
dilation of pupil
movement of eyeball downward and outward on damaged side
loss of accommodation for near vision
diplopia (double vision)

31

Damage to trochlear nerve

strabismus
diplopia

32

damage to abducens

affected eyeball can't move laterally beyond midpoint and eyeball is usually directed medially

33

CN V 3 branches

Trigeminal nerve (both motor and sensory)
Sensory 3 branches
1. Ophthalmic V1
2. Maxillary V2
3. Mandibular V3

34

Ophthalamic nerve covers

sensory from skin over upper lid,
cornea
lacrimal glands
upper nasal cavity
side of nose
forehead
anterior half of scalp

35

where does Ophthalmic pass to get trigeminal ganglion

superior orbital fissure

36

Maxillary covers

sensory from mucosa of nose
palate
part of pharynx
upper teeth
upper lip
lower eyelid

37

where does maxillary pass through to join trigeminal ganglion

foramen rotundum

38

Mandibular nerve covers

sensory from anterior 2/3 of tongue (not taste),
cheek and its mucosa,
lower teeth
skin over mandible
side of head anterior to ear
mucosa of floor of mouth

39

where does mandibular nerve pass to join trigeminal ganglion

foremen ovale

40

What is the uniqueness of CNV?

Largest cranial nerve has both motor and sensory

41

what does trigeminal motor nerve do? and where is it?

in mandibular branch
supply mm of mastication
these motor neurons mainly control chewing

42

What is main pathology of Trigeminal nerve?

Trigeminal neuralgia (tic douloureaux)
Sharp cutting intense pain that last for a few seconds to a minute
is caused by anything that presses on the trigeminal nerve on its branches (V2 or V2 and V3 - lip, face, tongue)
pain is within the nerve's distribution

43

what are possible causes of trigeminal neuralgia

local compressions
herpes zoster, vascular lesions, tumours
demyelinating conditions with subsequent scarring (MS)
ideopathic

44

CN VII

facial nerve
sensory and motor and autonomic

45

CNVII sensory route

Taste buds of anterior 2/3 of tongue ->stylomastoid foremen (temporal bone) -> genuculate ganglion -> pons -> thalamus ->gustatory area of cerebral cortex #43

also sensory axons from skin in ear canal (relay touch, pain, heat and cold)

46

CN VII motor nerve route

nucleus in pons -> stylomastoid foremen -> fascial expression mm, stylohyoid mm, posterior digastric mm, stapedius mm

47

CNVII autonomic nerve route

Superior salivatory nucleus ->
1. pterygopalatine ganglion ->lacrimal gland (tears), nasal gland (snot), palatine gland

2. Submandibular ganglion -> submandibular + sublingual glands

48

CNVII pathology

Bell's palsy: paralysis of the muscles of facial expression on the same side as the lesion. unilateral weakness. onset can be rapid. If sensory and autonomic affected, the patient can't control lacrimation, decrease in salivation, can not taste on anterior 2/3 of tongue, heightened sensitivity of hearing. Sagging of face and eyelid

49

how do you differentiate stroke and Bell's palsy?

Stroke affect lower half of facial muscles. The patient can control eye brow or can close eyes. The patient with Bell's palsy can not.