Singh 4: Cranial Nerves Flashcards
Go play the cranial nerve identification quiz when you come across this card
Learning objective states “identify the surface anatomy of the cranial nerves as they exit the brain”
Most of the cranial nerves are exiting the brainsteam on the ______ surface with ONE EXCEPTION
The _______ nerve exits on the ____ surface
Most of the cranial nerves are exciting the brainstem on the ventral surface with ONE EXCEPTION
Cranial nerve number 4 (trochlear) exits on the dorsal surface
What are the two pneumonics used to
- Name all of the cranial nerves
- Decide whether or not they are involved with Sensory functions , Motor functions , or both?
Naming the Cranial Nerves:
On Old Olympus’ Towering Tops A French and German Viewed Some Hops
Function: Some Say Marry Money But My Brother Says Big Brains Matter More
I: Olfactory
II: Optic
III: Occulomotor
IV: Trochlear
V: Trigeminal
VI: Abducens
VII: Facial
VIII: Vestibulocochlear/auditory
IX: Glossopharyangeal
X; Vagus
XI: Spinal Accessory
XIII: Hypoglossal
All of the nuclei of the cranial nerves are located with the three major segments of the ______
All of the nuclei of the cranial nerves are located within the three major segments of the brainstem
Most of the cranial nerves can be seen on the ________ surface of the brainstem
Most of the cranial nerves can be seen on the VENTRAL surface of the brainstem
The one exception is cranial nerve 4 (trochlear) which can be seen on the dorsal surface of the brainstem
Cranial Nerve I
Name?
Function?
Damage can lead to?
Olfactory Nerve (I)
Sensory function: smell
Damage can lead to:
Anosmia (absent sense of smell)
Hyposmia (reduced sense of smell)
Phantosmia (smell that isn’t there)
Dysosmia (distorted sense of smell)
Orient yourself to this picture
What axis are you looking at?
You are looking at the ventral surface of the brainstem
Therefore, the olfactory nerve sits near the FRONT part of the brain if you are looking at horizontal axis
SO olfactory nerve is more rostral.
the last nerve is more caudal (more towards the back)
One of the earliest signs of Alzhiemer’s disease is a loss of smell
Knowing the anatomy of the cranial nerves, where does alzhiemer’s start?
Dorsal
Ventral
Rostral
Caudal
Olfactory nerve (cranial nerve 1) is in charge of smell
Olfactory nerve is near the more rostral part of the brain (near the front)
as you go from cranial nerve 1 to cranial nerve 11, you are going from a more rostral part of the brain to the more caudal part of the brain
Therefore, alzhiemer’s disease starts in the rostral parts of the brain
Cranial Nerve II
Name?
Function?
Damage causes?
Optic Nerve (II)
Sensory function: vision
Damage: visual defects
A pituitary tumor sits right below the ______
When you get a pituitary tumor that compresses that ______, the resulting damage is called what?
A pituitary tumor sits right below the optic chiasm
When you get a pituitary tumor that compresses the optic chiasm, you get a defecit called Bitemporal hemianopsia (otherwise known as tunnel vision)
Therefore damage to the optic chiasm itself, causes bitemporal hemianopsia
Cranial Nerve III
Name?
Function?
Damage defecits?
Occulomotor Nerve (III)
Motor function
The occulomotor nerve controls 4 extrinsic muscles of the eye that influence gaze:
- (it controls the superior rectus, which holds gaze upwards, and the medial rectus, which pulls gaze medially)
- It also controls the levator palpebrae (elevates eyelids)
Damage: gaze will be down and out, eyelid will droop
Explain what the Edinger Westphal nucleus within Cranial Nerve 3 does
Damage to it will cause what?
Within cranial nerve 3 (occulomotor), there is a Edinger Westphal nucleus:
This is important in constriction of the pupils
If you get damage to this, you will see the pupils dilating (mydriasis)
Cranial Nerve IV
Name?
Function?
Damage will result in?
Trochlear Nerve (IV)
Function: motor control of eye movement
Innervates the superior oblique muscle
Trochlear (4) is the only cranial nerve to exit dorsally from the brainstem, cross over a innervate a contralateral structure
The superior oblique muscle allows the eye to focus in and down towards the nose
Therefore, damage to the trochlear nerve will cause the eye to go up and out
You have a pt who’s eye is going DOWN and OUT
And their eyelids are drooping
Which cranial nerve was effected?
Cranial Nerve 3 occulomotor
damage causes down and out and eyelid drooping
You have a pt who’s gaze is up and out
Which cranial nerve was damaged?
Pt who’s gaze is UP and out
Cranial Nerve 4 (trochlear) was damaged
Cranial nerve 4 controls superior oblique (allows the eye to focus in and down)
Explain the pneumonic to remember which cranial nerves control which muscles in the eye?
There are three cranial nerves that control muscles in the eye: Occulomotor (3), Trochlear (4), and Abducens (6)
LR6SO4
6 (abducens) controls the lateral rectus muscle (damage to 6 causes the eye to deviate medially)
4 (trochlear) controls superior oblique (damage to this will cause the eye to go up and out
Cranial Nerve 5
Name?
Function?
3 major divisions?
Cranial nerve 5: Trigeminal
AKA the big one
The Trigeminal Nerve has 3 major divisions:
Opthalmic: sensory innervation of face and scalp, has sympathetic fibers that control pupil dilation
Maxillary: sensory from lower eyelid, cheeks, upper lip
Mandibular (sensory and motor): main motor division of CN 5, supplies muscles of chewing, helps attenuate loud noises
Serves both sensory and motor
If you are at a rock concert, and the music is really really loud, which cranial nerve helps dampen the damage of that loud music?
The Manidibular division of the Trigeminal Nerve (5) helps attenuate loud noises
Explain some defecits one would experience with a damaged cranial nerve 5
If you damage your trigeminal nerve (5)
you will have problems feeling pain and temp in forehead (opthalmic)
problems chewing (mandibular division)
Cranial Nerve 6
Name?
Function?
Damage to it will cause?
Abducens (VI)
Motor control of eye movement.
Innervates the lateral rectus muscle
The lateral rectus muscle pulls the eye outward
Therefore, injury to cranial nerve 6 will cause the eye to deviate medially
Cranial Nerve 7
Name
Functions:
Damage results in?
Facial Nerve (VII):
Has both motor and sensory functions
Functions are related by 3 nuclei:
Motor nucleus: facial expression
- dorsal: upper face
- ventral: lower face
- damage to motor nucleus: Bell’s Pallsy
Salivatory Nucleus:
- tear ducts, salivary glands
- damage results in dry eye
Nucleus solitarius: sensory for anterior 2/3 of tongue
- damage results in loss of taste to front part of tongue
Cranial Nerve Number 8:
Name
Function
Damage results in?
Vestibulocochlear/Auditory Nerve (VIII):
Sensory Function
2 components: auditory and vestibularcochlear (balance)
Important in relaying infor related to orientation and movement of head in space
Cranial Nerve 9:
Name?
Function?
Damage will result in?
Glossopharyngeal (IX):
Motor and sensory:
Motor: \raises and dilates pharynx, helps with swalling (as do 10 and 12), and innvervates parotid gland (saliva production)
Sensory:
pain, temp, touch to pharynx and posterior tongue
(damage results in loss of gag reflex)
Blood pressure info from carotid sinus
Taste from posterior 1/3 of tongue
Damage to cranial nerve number 9 will cause what?
Glossopharyngeal (IX)
damage will cause a LOSS of gag reflex
lose taste from posterior 1/3 of tongue
issues in regulating BP
