Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BS IV, Module II > 7. CN II, III, IV and VI > Flashcards

7. CN II, III, IV and VI Flashcards

1
Q

CN II - Optic N.
____ mediate vision from the photoreceptors (rods and cones) of the retina

Rods and cones transduce light energy into an electrical signal which passes to ____ cells (the primary sensory neurons in the visual pathway), then ____ cells

The axons of retinal ganglion cells from the ____

A

special somatic afferents (SSA)
bipolar
ganglion
optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

MIDDLE CRANIAL FOSSA

  • Optic Canal
  • Chiasmatic Groove

After coursing through the OPTIC CANALS, the optic nerves end grossly at the level of the ____ where a decussation of fibers occurs

A

optic chiasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Decussating fibers are vulnerable here to lesions of the ____ and the ____ diencephalon
including the ____

A

pituitary gland
ventral
hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The OPTIC NERVE is technically NOT a nerve, but a ____ of the CNS, because…

  • Like CN I, it is comprised of axons of ____, rather than primary, sensory neurons
  • It is covered with CNS ____ and ensheathed by the ____
A

white matter tract
secondary
myelin
meninges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Ganglion cell axons converge toward the ____, where they turn posteriorly, pass through the ____ of the sclera and exit the eyeball

The ____ features the densest concentration of cones and a ____
ratio of cones to ganglion cells for maximal visual acuity and color vision

A

optic disc
lamina cribrosa
macula
1:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Consistent with the idea that the OPTIC NERVE is a CNS tract, note that upon leaving the LAMINA CRIBROSA, the nerve is bathed in ____ and invested with all ____ meningeal layers

Increased pressure in the subarachnoid space may compress CN II and produce swelling of the nerve: ____

Recall the Central artery of the retina?

A

CSF
three
papilledema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ophthalmoscopic examination of the ____ is a crucial part of any clinical neurologic evaluation

May provide clues as to the presence of ____ leading to an increase intracranial pressure (ICP)

A

optic fundus

intracranial disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

GANGLION CELLS receive Inputs primarily from
the ____ CELLS

BIPOLAR CELLS are the primary ____ neurons in the visual pathway, receiving inputs from the specialized retinal photoreceptor cells……the
____ and ____

… but ca. 10% project to brainstem (midbrain) nuclei or hypothalamus to provide visual inputs crucial for:
	• Reflex maintenance of \_\_\_\_
	• Coordination of \_\_\_\_
	• Control of the size of the \_\_\_\_
	• \_\_\_\_ regulation
A

bipolar
sensory
rods
cones

balance
eye movements
pupils
pineal gland

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Axons from the NASAL HALVES of the retinas, receiving inputs from the ____
VISUAL FIELDS, cross the midline at the
____

Most axons in each
OPTIC TRACT
terminate in the
____ of the THALAMUS…

A

temporal
optic chiasm
lateral geniculate nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Visual inputs project to PRIMARY VISUAL CORTEX surrounding the ____ fissure in the ____ LOBES of the brain

A

calcarine

occipital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Within the optic chiasm, axons from the nasal halves of the retinas cross the midline… … resulting in the information from the
____ half of the visual
field from both eyes being
carried in the ____ optic tract and vice versa

A

right

left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

CN II Lesions

  • Prechiasmatic - to ____ or ____
    • ____
    • glaucoma (atrophy of optic disc w/ inc IOP)
    • ____ (MS, syphillis, lyme)
    • facial trauma
  • Chiasmatic - to ____
    • ____ (benign neoplasias)
    • ICA aneurysm
  • Postchiasmatic - lesions to ____, LGN or ____
    • ____, TBI, neoplasm
A

retina
optic nerve
macular degeneration
optic neuritis

optic chiasm
pituitary adenomas

optic tract
optic radiations
stroke

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Prechiasmatic lesion - ____
Chiasmatic lesion to ducssating axons from ____

If the lesion to the nerve is incomplete, a ___ or blind spot in that eye’s visual field results

A

mononuclear blindness
nasal hemiretinae
scotoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Prechiasmatic lesion - mononuclear blindness

If the lesion to the nerve is incomplete, a
____
or blind spot in that eye’s visual field results

Chiasmatic lesion - to decussating axons from nasal hemiretinae
Temporal visual fields are lost: loss of
peripheral vision ____

____ lesion

A

scotoma
“tunnel vision”
postchiasmatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Having completed study of both CN II and CN V1 we must now examine the other cranial nerves
found within each orbital cavity……all of which enter the orbit through the ____

A

superior orbital fissure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

CN III Oculomotor Nerve

CN III arises from the medial aspect of the CEREBRAL ____ of the midbrain

GSE
fibers
innervate most ____ muscles

GVE
fibers
are ____ synapsing in the ____ ganglion

A

peduncles
extraocular
preganglionic parasympathetic
ciliary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

CN IV Trochlear Nerve

CN IV exits the brain below the ____ on the ____ aspect of
the MIDBRAIN

GSE
fibers
innervate the ____

A

inferior colliculus
dorsal
superior oblique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

CN IV follows the ____ intracranial course of any of the cranial nerves

Note that, atypically, the LMNs lie ____ to the SO muscle innervated

A

longest

contralateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

CN VI Abducent Nerve

CN VI leaves the brain from the ____ SULCUS

GSE fibers innervate the ____ muscle

Note that
the LMNs lie ____ to the LR muscle innervated

A

inferior pontine
lateral rectus
ipsilateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

CN VI follows the longest ____ course of any cranial nerve… Thus it is frequently involved in ____!

A

intradural

intercranial disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Before we can discuss
what happens in the CILIARY GANGLION we must look at CN V1 as well because… …As a rule, ____ axons arising from the parasympathetic ganglia in the head reach their targets by “piggy-backing” on branches of CN ____

A

postganglionic

V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

V1 HAS THREE MAIN BRANCHES IN THE ORBIT

  • ____ nerve
  • Frontal nerve
  • ____ nerve
A

nasociliary

lacrimal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

A quick review of the extraocular muscles is needed to appreciate the distribution
of the ____ fibers in the oculomotor nerve

A

GSE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The MEDIAL and LATERAL RECTUS muscles move the eyeball around a single ____ axis only

Lateral rectus - ____
Medial rectus - ____

A

vertical
abduction
adduction

25
Q

Each of the remaining muscles moves the eye around all ____ of these rotational axes

This is explicable by considering the disparity
of the ____ and ____ AXES

A

three
visual (optical)
orbital

26
Q

Inferior oblique
____
____
____

Superior oblique
____
____
____

Superior rectus
____
____
____

Inferior rectus
____
____
____

Recall that ____ and ____ occur around a transverse axis through the center of the eyeball

A

elevates
abducts
extorts

depresses
abducts
intorts

elevates
adducts
intorts
depresses
adduts
extorts

elevation
depression

27
Q

Recall too that ____ and ____ occur around a Vertical axis through the center of the eyeball

A

abduction

adduction

28
Q

Testing extraocular muscles is important for diagnosing lesions of cranial nerves ____, ____ and ____, ____ and ____

Since some of the muscles share common actions (e.g. elevation and depression), it is essential to i____ and test each muscle separately

A 
III
IV
VI
midbrain
pons

isolate

29
Q

Isolating individual muscles which share elevation or depression functions is accomplished by first either abducting or adducting the eye so as to place the selected muscle at the maximal mechanial advantage, ____ to the transverse axis through the eyeball, and the synergist at a disadvantage, ____ to that same transverse axis

A

perpendicular

parallel

30
Q

FOR EXAMPLE, with adduction, SUPERIOR RECTUS
lies almost parallel to the ____ Axis around which elevation and depression occur the SR

Thus it has no ____ advantage and is unable to elevate the eyeball

Only the ____, perpendicular to the transverse axis, may elevate the adducted eyeball

A

transverse
mechanical
inferior oblique

31
Q

In abduction, INFERIOR OBLIQUE
lies almost parallel to the ____ axis
and is thus unable to elevate the eyeball

Thus only the ____, perpendicular to the transverse axis, may elevate the abducted eyeball

A

transverse

superior rectus

32
Q

TO TEST THE MUSCLES INNERVATED BY CN III - ____ NERVE

A

oculomotor

33
Q

To test CN IV: ____

To test CN VI: ____

A

superior oblique

lateral rectus

34
Q

Before passing through the superior orbital fissure, CN III, IV and VI all course through the ____

A

cavernous sinus

35
Q 
All \_\_\_\_ nerves are vulnerable to compression
and lesion
within the
CAVERNOUS SINUS
resulting from:
- \_\_\_\_ of the cavernous sinus
Intracavernous \_\_\_\_ aneurysms
 3) Aneurysms of components and branches of the \_\_\_\_
	4) \_\_\_\_ expanding \_\_\_\_ tumors
A 
three
septic thrombosis
ICA
circle of willis
laterally
pituitary
36
Q

Lesions of CN III, IV or VI produce
____- paralysis of extraocular
musculature

A

ophthalmoplegia

37
Q

Right oculomotor nerve lesion(GSE)

  • Ptosis (drooping) of eyelid from paralyzed ____
  • Eyeball “down and out”(abducted and slightly depressed) because ____(6) and ____(4) are unopposed…
  • So all muscles paralyzed except ____ and ____
A 
levator palpebrae superioris
LR
SO
LR
SO
38
Q

This woman demonstrates a lesion of the left CN ____

Left eyeball is ____ due to the unopposed pull of the ipsilateral ____ rectus

A

VI
adducted
medial

39
Q

Paralysis of the lateral rectus is one cause of ____, the inability to direct both eyes towards the same object,
which produces ____

On attempted left lateral gaze

On normal right lateral gaze

____
(From a CNVI lesion produces ____ diplopia)

A 
strabismus
diplopia (double vision)

medial strabismus
horizontal

40
Q

RIGHT TROCHLEAR NERVE (CN IV) PALSY
With the loss of the ____, which depresses
and abducts, the eyeball is ____ and ____

Patient will complain of a ____ diplopia when he attempts to depress the affected eye

This is particularly alarming when descending ____!!!

Patient may tilt his head ____ from the side of the lesioned CN IV to reduce the diplopia

A

superior oblique
elevated
adducted

vertical
stairs
away

41
Q

In order to either maintain or change visual fixation on a moving object, the eyes must move together with exquisite precision as the result of coordinated contraction of the ____ muscles in each orbit

This requires ____ co-ordination and control above the ____ of the cranial nerves

A

extraocular
CNS
brainstem nuclei

42
Q

FRONTAL EYE FIELDS

The ____ contains centers for conjugate eye movements \

A

frontal lobe

43
Q

Cortical centers initiating ____ eye movements which redirect gaze are found In the the ____ eye fields

They override involuntary brainstem centers in the
____ and ____ which normally coordinate the conjugate ____ of gaze on moving objects by both eyes

A 
voluntary
frontal
pontine reticular formation
midbrain
fixation
44
Q

It is now time to consider the AUTONOMIC INNERVATION of orbital structures

The shape of the LENS is adjusted by contraction of
the ____ MUSCLE to keep the image of an object moved nearer to the eyes in sharp focus

  • Ciliary muscle
  • Zonule fibers
A

ciliary

45
Q

Contraction of the ciliary muscle ____ the curvature
of the lens and enables ____… an adaptation of the visual
apparatus for ____ viewing

Near vision also requires
____ of the pupil… and ____ of the eyes resulting from bilateral contraction of ____ RECTUS

A

increases
accommodation
near

constriction
convergence
medial

46
Q

The ____ is under the active control of two antagonistic muscles: a ____ and a ____

The ____ is the central aperture of the IRIS, which functions like the diaphragm of a camera

A

diameter
constrictor
dilator
pupil

47
Q

The PUPILARY CONSTRICTOR and CILIARY MUSCLES are innervated by ____ arising from ____ GANGLION

A

postganglionic parasympathetic

ciliary

48
Q

Light directed into either eye usually produces ____ pupillary constriction

A

bilateral

49
Q

____ - inequality in the size of the pupils under changing light conditions - suggests a lesion in a pupillary ____ pathway

A

anisocoria

autonomic

50
Q

____ fibers in CN III are carried in the ____ division of the nerve and synapse in the CILIARY GANGLION

Postganglionic fibers are carried by branches of the ____ nerve to their targets

A

GVE
inferior
nasociliary

51
Q

CNIII PATHWAY!

A

YA

52
Q

IN SUMMARY,
POSTGANGLIONIC PARASYMPATHETICS FROM THE CILIARY GANGLION DISTRIBUTE TO:

PUPILLARY ____
If this parasympathetic pathway is lesioned…
• The pupil will be fixed and ____
• The PUPILARY ____ (CN ____-CN____) will be lost

____ MUSCLE
If this parasympathetic pathway is lesioned…____ vision will be impaired

A 
constrictor
dilated (mydriasis)
light reflex
II
III

ciliary
near

53
Q

Right oculomotor nerve lesion

  • NO pupillary ____ reflex (constriction of pupil in affected eye in response to light)
  • Dilation of ____, since parasympathetics are interrupted and ____ is unopposed
  • No accommodation of lens because ciliary muscle is paralyzed - LOSS OF ____ VISION
A

light
iris
dilator pupillae
near

54
Q

Considering the SYMPATHETIC innervation of orbital structures opens us up to recalling the origin of all head and neck sympathetics

____. and the ____ of the upper eyelid

A

pupillary dilator muscle

superior tarsal muscle

55
Q 
Almost all postganglionic sympathetic
fibers supplying the head are distributed
through the
\_\_\_\_
PLEXUSES which surround the
INTERNAL and
EXTERNAL \_\_\_\_
ARTERIES
and their branches

THE POSTGANGLIONIC SYMPATHETIC INNERVATION OF THE HEAD ARISES FROM THE
____

A

periarterial
carotid
superior cervical ganglion

56
Q

Preganglionic sympathetic innervation of the orbit arises from the ____ CORD SEGMENTS

These fibers ascend thru the cervical sympathetic chain and synapse in the ____

The postganglionic fibers run in the ____ NERVE and PLEXUS and then enter
the orbit… …They run through the ciliary ganglion without ____
and travel on
____ NERVES (____ and ____) to reach their targets

  THE SYMPATHETICS
IN THE ORBIT INNERVATE:
	• The \_\_\_\_
	• The \_\_\_\_
	• The \_\_\_\_ and its branches
A 
T1-T2
superior cervical ganglion
internal carotid
synapsing
ciliary
long
short

pupillary dilator
superior tarsal muscle
ophthalmic artery

57
Q

Recall that branches of the OPHTHALMIC ARTERY distribute to the
forehead,
root and
bridge of the nose

  • ____
  • ____
  • ____
A

supraorbital
supratrochlear
dorsal nasal

58
Q

Horner’s Syndrome

INTERRUPTING THE SYMPATHETIC PATHWAY DESCRIBED PREVIOUSLY PRODUCES THE FOLLOWING SYMPTOMS:

A FIXED, CONSTRICTED PUPIL ____

A DROOPY EYELID ____

LOSS OF FOREHEAD SWEATING ____
as sympathetic ____ innervation of the ____ and ____ branches of the ophthalmic artery is lost

A 
(miosis)
(partial ptosis)
(anhydrosis)
sudomotor
supraorbital
supratrochlear

BS IV, Module II (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions