Cranial nerves

Question 1

what are the cranial nerves

MENUMONIC ?

Answer 1

OH: olfactory nerve (CN I)
OH: optic nerve (CN II)
OH: oculomotor nerve (CN III)
TO: trochlear nerve (CN IV)
TOUCH: trigeminal nerve(CN V)
AND: abducens nerve (CN VI)
FEEL: facial nerve (CN VII)
A: auditory (or vestibulocochlear) nerve (CN VIII)
GOOD: glossopharyngeal nerve (CN IX)
VELVET: vagus nerve (CN X)
SUCH: spinal accessory nerve (CN XI)
HEAVEN: hypoglossal nerve (CN XII)

Question 2

which cranial nerves are sensory and which are motor

Answer 2

some -O: olfactory nerve (CN I)
say -O: optic nerve (CN II)
marry -O: oculomotor nerve (CN III)
money- T: trochlear nerve (CN IV)
But- T: trigeminal nerve(CN V)
My-A: abducens nerve (CN VI)
Brother-F: facial nerve (CN VII)
says-A: auditory (or vestibulocochlear) nerve (CN VIII)
big-G: glossopharyngeal nerve (CN IX)
brains-V: vagus nerve (CN X)
Matter-S: spinal accessory nerve (CN XI)
most -H: hypoglossal nerve (CN XII)

Question 3

Olfactory , optic and oculomotor nerve functions
ophthalmic nerve palsy ?

(4)

Answer 3

1) Olfactory nerve = smell ( through cribriform plate)
2) Optic nerve = sight ( optic canal )
3) Occulomotor nerves = eye movements ( palsy can result in ptosis and down and out eye )

Question 4

what does trochlear , trigeminal and Abducens do ?

6

Answer 4

Trochlear nerve = eye movement down , and horizontally . Palsy causes vertical diplopia ( defective downwards gaze)

Trigeminal nerve =facial muscles of mastication ( 3 branches : ophthalmic , maxillary and mandibular ) .
Palsy: can cause facial paralysis , deviation of the jaw to the weaker side, trigeminal neuralgia, loss of corneal reflection

Abducens nerve= outwards gazes = abduction ( away from midline )
Palsy results in defective abduction → horizontal diplopia ( the eye points in wards, as it can’t move outwards )
- later and medial rectus muscles

Question 5

FEEL: facial nerve (CN VII)
A: auditory (or vestibulocochlear) nerve (CN VIII)
GOOD: glossopharyngeal nerve (CN IX)

Answer 5

Facial nerve 7= Facial movement & Taste (anterior 2/3rds of tongue) , Lacrimation , Salivation
Palsy : can cause paralysis of lower and upper face, loss of corneal reflex , loss of taste

Auditory / vestibulocochlear nerve = Hearing and balance-iaga
Palsy :Hearing loss , Vertigo, nystagmus (involuntary eye movements )
Acoustic neuromas are Schwann cell tumours of the cochlear nerve

Glossopharyneal nerves = Taste (posterior 1/3rd of tongue) ,Salivation, Swallowing , Mediates input from carotid body & sinus

Question 6

V: vagus nerve (CN X)
S: spinal accessory nerve (CN XI)
H: hypoglossal nerve (CN XII)

Answer 6

Vagus nerve = parasympathetic fibers
Palsy :Lesions may result in, uvula deviates away from site of lesion
loss of gag reflex (efferent)

Spinal acessory nerve = head and shoulder movements
palsy : weakness turning head to the opposite site of lesion

Hypoglossal Nerve = Tongue movement
Palsy : Tongue deviates towards side of lesion

Question 7

what nerves move the eye

Why do we Get vertical and horizontal diplopia’s ?

Answer 7

1) Optic nerve
2) Occulomotor nerve
3) Trochlear nerve
4) Abducens nerve

Vertical diplopia indicates vertical alignment of the images, which usually suggests pathology in the vertical muscles:
- superior oblique, inferior oblique, superior rectus, and inferior rectus

Horizontal diplopia suggests pathology of the medial or lateral rectus.

Question 8

how can you differentiate between UMN lesions and LMN lesions?

Answer 8

UMN = you can wrinkle your forehead 
LMN = you can't wrinkle your forehead