Cranial nerves

Question 1

Name all the cranial nerves, which are sensory/motor?

Which are parasym

Answer 1

CNI - olfactory S
CN II - optic S
CN III - oculomotor M
CN IV - trochlear M 
CN V-  trigeminal B
CN VI - abducens M
CN VII - facial B
CN VIII - vestibular S
CN IX - glossopharyngeal B
CN X - vagus B
CN XI - acessory M
CN XII - hypoglossal M

parasym = 10, 9, 7, 3

Question 2

What is CNI? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 2

CNI - Olfactory nerve

1. Sense of smell
2. Cribiform plate
3. Test olfaction using smell stickers

*Parkinson’s, epilepsy

damage = Anosmia on ipsilateral side, fratures to anterior cranial fossa

Question 3

What is CNII? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 3

CNII - Optic nerve

1. Vision
2. Optic canal
3. Test eyes/visual pathways using -visual fields, pupil reflexes, visual acivity, fundoscopy

*Syphills ‘accommodating but slow to react’, Horners syndrome, Holmes-adie ‘tonic’ pupil, physiological anisocoria,

Question 4

What is CNIII? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 4

CIII - Oculomotor

1. a) Motor - movement of eyeball, all the extra-ocular muscles EXCEPT (VI - lateral rectus, IV - Superior oblique (head tilt)
   b) Parasym - pupillary constriction and accomodation, cillary muscle of eyeball = both via ciliary ganglion
2. Leaves via Superior orbital fissure

Damage = ptosis of the eyelid on ipslateral side

Question 5

What is CNIV? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 5

CN IV - Trochlear
1. motor, movement of eyeball = superior oblique

2. Leaves via superior orbital fissure
   * Trochlear palsy = hypertropia so head tilts to the opposite side, eg trauma

damage = Double vision when they look down

Question 6

What is CNV? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 6

CNV - Trigeminal

v1. trigeminal opthalmic = SOF
v2. trigeminal maxillary = foramen rotundum
v3. trigeminal mandibular = foramen ovale (SomeRandonhOle)

1. Sensory roots to trigeminal sensory nuclei, thalamus then cortex
   Sensory - Jaw jerk, touch and position of face, pain and temp from face
   Motor - mastication

Damage = Loss of corneal reflex (blink)on ipslateral

Question 7

What is CNVI? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 7

Abducens - motor, lateral rectus

Damage: Inability to abduct eye
SOF

Question 8

What is CNVII? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 8

Facial

sensory: anterior 2/3, tongue
motor: muscles of facial expression (contralateral of lower, bilateral innervation of upper facial muscles)
parasym: salivary and lacrimal glands

Question 9

What is CNVIII? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 9

Vestibulo-cochlear

Cochlear: auditory (from organ of corti, semicircular canals, utricle and succule) - cochlear nerve

Vestibular: acceleration, postion
damage can cause: nystagmus, dizziness, nausea, loss of balance

nystagmus-rapid eye movements, tumour could affect facial nerve
(Tuning fork)

Question 10

What is CNIX? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 10

Glossopharyngeal: M, S, P
emerges from the lateral sulcus of the medulla and exits via the jugular foramen accompained by the vagu and accessory nerves

taste, sensory and motor of pharynx, visceral innervation of carotid body and sinus, parasym of salivary gland, posterior 1/3 of tongue

Question 11

What is CNX? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 11

Vagus nerve - jugular foramen
Sensory and motor of pharynx, larynx and oesophagus, viseral from thorax and abdomen, including aortic body and arch, parasym of thoracic and abdominal viscera

Question 12

What is CNXI? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 12

Movement of head and shoulders - sternomastoid and trapiez

Damage: paralysis of the sternocleidomastoid and superior trapezius muscles on ipslateral

Question 13

What is CNXII? What does it sense? What foramina of the skull does it leave via? How can it be tested.

Answer 13

Movement of tongue- intrinsic and extrinsic

Damage: paralysis of the ipslateral half of the tongue ( ipsilateral; ‘licks the lesion’ )

Question 14

What is bell’s palsy? what may cause it

Answer 14

Facial nerve LMN lesion = loss of whole of one side of facial movement on the same side

Cause: fracture to petrous bone, middle ear infection, tumour, inflammation of parotid gland

An UMN lesion would cause contralateral weakness in lower face but not upper