Afferent Cranial Nerves (Ocular Focus)

Front 1

what is the difference between cranial and spinal nerves

Back 1

cranial nerves attach to forebrain and brainstem, spinal attach to spine

Front 2

What are the 12 cranial nerves

Back 2

I. Olfactory
II. Optic
III. Oculomotor
IV. Trochlear
V. Trigemental
VI. Abducens
VII. Facial
VIII. Acoustic
IX. Glossopharyngeal
X. Vagus
XI. Spinal Accessory
XII. Hypoglossal

Front 3

What is unique about the first 2 CN

Back 3

CN I and II have their cell bodies located within their receptor organs, the rest have their cell bodies located within their nuclei

Front 4

Which CN are not true cranial nerves

Back 4

I and II, sensory nerve fiber tracts

Front 5

where do sensory and motor nuclei tend to be located

Back 5

lateral brainstem and medial brainstem respectively

Front 6

which is the largest cranial nerve

Back 6

CN V

Front 7

How does information arrive into the central nervous system

Back 7

via afferent fibers

Front 8

What are te two components of CN III

Back 8

somotic motor component and a visceral motor component

Front 9

what are the characteristics of the somotic motor division of the CN III

Back 9

this division of the CN III innervates the MR IO IR SR and levator

Front 10

what are the characteristics of the visceral motor division of the CN III

Back 10

this supplies the parasympathetic component of the pupillary sphincter and the ciliary body and smooth muscle of the eyelid

Front 11

What is unique about CN III nuclei

Back 11

the nuclei is actually a group of sub nuclei, for each of the EOM's except LR and SO

Front 12

Where is the oculomotor nerve nucleus

Back 12

located in the midbrain, ventral to the cerebral aquaduct, at the level of the superior colliculus

Front 13

What is the edinger-westphal nucleus

Back 13

it is responsible for supplying parasympathetic innervation to the ciliary and iris sphincter, located within oculomotor subnucleus

Front 14

What structures are located to CN III nucleus and what do they do (6).

Back 14

1. inferior colliculus - auditory reflexes
2. superior colliculus- visual reflexes connects
3. cerebral aquaduct- connects 3rd and 4th (fluid cavities of the brainstem
4. red nucleus- limb flexiblity
5. cerebral peduncles- movement of limbs connects crainstem to cerebellum
6. substantia nigra- linked to basal ganglia

Front 15

Describe the oculomotor nerve pathway

Back 15

1.fibers from the individual muscle join together, forming the fascicular part of the nerve. this then passes through the red nucleus and the cerebral peduncles

2. these fibers the emerge on the anterior aspect of the midbrain as the oculomotor nerve

3. moves forward passing between the superior cerebellar and posterior cerebral arteries. it the runs slightly inferior to the posterior communicating artery of the circle of willis.

4. the nerve pierces the roof o the cavernous sinus and runs within its lateral wall above the trochlear nerve

5.the nerve exits the sinus, entering the orbit through the SOF ( within the annulus of zinn), where it dvides into superior and inferior branches.

6a. the superior branch runs medially above the optic nerve and innervates SR and levator

6b. runs below the optic nerve and innervates the, MR IO IR. Parasympathetic fibers also remain with the inferior branch until it innervate MR and IR, it then branches off to innervate the cilliary ganglion (crab shape) (ciliary body and iris)

Front 16

Cranial nerve III is often referred to as what kind of nerve

Back 16

aneurysm because it passes between superior and posterior cerebral arteries. this often causes CN III palsies between 5th and 7th decade of life

Front 17

what are the 4 D's and what do they indicate

Back 17

the four d's are down and out, droopy lid, dialated pupil and diplopia and they represent a complete CN III palsy

Front 18

a widely dilated pupil and pain and CN III palsy indicates an aneurysm where?

Back 18

in the circle of willis

Front 19

if a CN III palsy is observed without dilated pupil what could be he cause (2).

Back 19

diabetes or hypertension

Front 20

where is the trochlear (CN IV) nucleus located

Back 20

in the midbrain anterior to the cerebral aquaduct, below the oculomotor nerve at the level of the inferior colliculus

Front 21

What is unique about CN IV and why is it sometimes referred to as the trauma nerve

Back 21

it is the only CN to cross and exit the brain stem dorsally, thus it innervates the contra lateral SO, exiting dorsally makes it more prone to injury

Front 22

Describe the pathway of trchlear nerve CN IV.

Back 22

1. As the nerve emerges from the dorsal midbrain, it decussates and curves around the cerebral peduncle at the upper borer of te pons. it emerges between the posterior and superior cerecral arteries cotinuing anteriorly, entering the dura at the front edge of the tentorium.

2. the nerve enters the cavernous sinus and lies between the oculomotor nerve and the opthalmic division of CN V.

3. while in the sinus the CN IV sends sensory nerve fibers to the opthalmic nrve. the nerve hen enters the orbit through SOF above the annulus of Zinn, outside the muscle cone

4. the trochlear nerve runs with the frontal nerve to the medial side of the orbit, above the levator and SR muscles and innervates the SO on the opposite side.

Front 23

what is the most common CN IV complication

Back 23

congenital CN IV palsy., with the second being aquired CN IV palsy usually from diabetes and hypertension

Front 24

A CN IV palsy often causes

Back 24

causing diplopia in opposite gaze. So a right SO palsy produces diplopia that is worse in left gaze, this often results in a head posture to resolve the diplopia

Front 25

which muscles have nerve fibers that cross in the brainstem area

Back 25

SR and SO

Front 26

CN IV is unique in what 4 ways

Back 26

1. thinnest
2. only nerve to exit te brainstem dosally
3. it is the only nerve to have all its lower motor neurons cross
4. has the longest intracranialcourse

Front 27

what does CN VI innervate

Back 27

LR

Front 28

where is the bducens nerve nucleus located

Back 28

near the midline of the pons, beside floor of the 4th ventricle

Front 29

Describe the PathwAay of the Abducens nerve

Back 29

1. after running through the pontine paramedian reticular formation (PPRF) it exits the brain stem from the ventral surface of the pons

2. it arises between the clivous bone and the pons and runs along the posterior slope of the petrous portion of the temporal bone. it then makes a sharp bend over the petrous ridge and enters the cavernous sinus.

3. once in the sinus, it lies near the lateral wall of the internal carotid artery.

4. it then gives off branches to the opthalmic berve

The abducens nerve enters the orbit through the SOF, within the annulus of zinn, and innervates the LR on the same side.

Front 30

CN VI palsy will have the greates deviation when?

Back 30

esotropic deviation in right gaze

Front 31

CN VI is often referred to as _____ because why?

Back 31

tumor nerve, because palsies result from pressure caused by growth of ponitine gliomaa in kids or nasopharyngeal tumor in adults

Front 32

CN VI palsies occur in kids also when?

Back 32

following viral illness and these can usually recover

Front 33

How common are CN III, IV VI palsies

Back 33

VI>IV>III

Front 34

Which is the largest CN

Back 34

Trigeminal nerve V

Front 35

CN V consists of (2)

Back 35

roots
1. motor
2. sensory

Front 36

What are the dvisions of CNV and which one are we inerested in

Back 36

Opthalmic CNV1- most intrested and only sensory function
2. Maxillary V2

3. Mandibular V3

Front 37

which is the smallest division of CN V and its branches

Back 37

opthalmic division
1. nasocliary
2. lacrimal
3.frontal

Front 38

which major ocular structure does CN V supply

Back 38

the cornea

Front 39

CN V palsy will lack sensation in one of its three divisions at least, what could we do to test this in case of CN V1

Back 39

we will be able to touch the cornea with a tissue and not feel it.

Front 40

what are 2 branches of the facial nerve CN VII which we are concerned with

Back 40

Zygomatic and temporal branches

Front 41

what is unique about the orbicularis muscle as it relates to CN VII

Back 41

two different branches supply the orbicularis muscle.
the zygomatic branch supplies the lower branch and the temporal branch supplies the upper part.

Front 42

CN VII stimulates what?

Back 42

orbicularis, facial expression and the lacrimal gland

Front 43

wha will one see if a patient has a CN VIII palsy

Back 43

one side of their face will be droopy, and they will not be able to close their eyelid on one side of their face.