Session 4

Question 1

Where do cranial nerves arise from?

How many are sensory,motor,mixed?

Answer 1

The level of the brainstem

4 mixed, 3 sensory, 5 motor.

Question 2

Role of the 3 sensory nerves?

Answer 2

Hearing and balance=VIII

Smell= I

Vision= II

Question 3

What nerves form taste?

Answer 3

They are both mixed. VII and IX.

Question 4

What 4 cranial nerves contain autonomic fibres?

Answer 4

III, VII, IX, X

Question 5

How are cranial nerves numbered?

Answer 5

How they enter the brainstem from rostralmto caudal.

Question 6

Name the 12 cranial nerves

Answer 6

I Olfactory
II Optic
III Oculomotor
IV Trochlear
V Trigeminal
VI Abducens
VII Facial
VIII Vestibulocochlear
IX Glossopharynx
X Vagus
XI Accesory
XII Hypoglossal

Question 7

What indicates an extradural haemorrhage? Ie history

Answer 7

Trauma,lucid interval,deterioration

Question 8

What’s a subaponeurotic haemorrhage?

Answer 8

One on the scalp usually with superficial temporal artery

Question 9

Presentation of subdural haemorrage?

Answer 9

Old, confused, bridging vein

Question 10

Subarachnoid haemorrage presentation?

Answer 10

Increase BP, severe headache, aneurysm

Question 11

What do all the mixed cranial nerves have in common?

Answer 11

They are all autonomics

Question 12

What two nerves arise prior to the brainstem?

Answer 12

Olfactory and optic

Question 13

Describe the route of the olfactory nerve

Type of nerve and function?

Name for loss of smell?

Answer 13

The olfactory nerves start at the root of the nasal cavity, they go through the cribriform foramina and form the olfactory bulb which turns into the olfactory tract. This goes to the Uncus part of the temporal lobe.

Sensory and smell.

Anosmia.usually from URTI.

Question 14

Describe the route of the optic nerve?

Answer 14

Impulse generated by retinal ganglion cells,communicate with rods and cones and the axons form the optic nerve. Goes through the optic canal, then the fibres merge at the optic chiasm and then reach the primary visual cortex where vision is perceived.

Question 15

Role of optic chiasm? Clinical problem?

Optic nerve type and role?

What’s the optic disc?

Why may one have a swollen optic disc (papillaodema)?

Answer 15

Mixing of sensory fibres from both optic nerves. Can be a problem if pituitary has a problem.if compressed can cause bitemporal hemianopia.

Sensory and vision.

Point at which the nerve enters the retina.

It carries an extension of the meninges so becomes swollen with raised ICP.

Question 16

How fair does the visual pathway with the optic nerve extend?

Why communication with optic tracts and brainstem?

Answer 16

From retina to occipital lobe

Allows certain reflexes e.g pupillary reflex to light.

Question 17

2 nerves arising from midbrain?

Answer 17

Oculomotor and trochlear

Question 18

Route of Oculomotor nerve?

Type of nerve fibres?

Answer 18

Arises from midbrain, runs through the lateral wall of the cavernous sinus,and goes through the superior orbital fissure.

Motor (majority of eye muscles e.g extra ocular muscles)
Autonomic (pupillary sphincter muscles)

Question 19

Why is the Oculomotor nerve squashed if raised ICP?

How can you test the Oculomotor nerve?

Causes of pathology?

Answer 19

The tentorium cerebelli and part of the temporal lobe can squash it.

Test eyelids and pupil reflexes to light. Pathology can cause dilation and double vision.

Haemorrage,aneurysms, cavernous sinuous thrombosis.

Question 20

Describe the route of the trochlear nerve?

Type of nerve and role?

Answer 20

Arises midbrain, goes through the lateral wall of the cavernous sinus and in through the superior orbital fissure.

Purely motor and innervates one extra ocular muscle (superior oblique)

Question 21

What cranial nerve has the longest route and where does it arise?

Consequences if this nerve is damaged?

Answer 21

The trochlear nerve arising from the dorsal aspect of the midbrain.

Diplopia from congenital palsies or raised ICP.

Question 22

4 cranial nerves arising from the pons?

Answer 22

Trigeminal, Abducens, fascial, vestibulocochlear

Question 23

Type of nerve and role of trigeminal?

Answer 23

Sensory and motor.
Sensory-main skin of face and scalp, deeper structures like nasal/oral cavity, meninges, paranasal air sinuses.
Motor-muscles of mastication.

Question 24

What three sensory regions of the face does the trigeminal ganglion split into? And what fossa/fissure do they enter?

Answer 24

Ophthalmic-sup orbital fissure then into the orbit

Maxillary-foramen rotundum then pterygopalatine fossa

Mandibular-foramen ovale then infratemporal fossa

Question 25

How would you test the muscles of mastication?

Answer 25

Jaw jerk which should give the corneal reflex

Question 26

Worry if ophthalmic division of trigeminal nerve gets shingles?

Answer 26

It includes the eye itself can cause blindness

Question 27

Branches of ophthalmic division of trigeminal?

Branches of maxillary?

Answer 27

Frontal(supraprbital and supratrochlear), lacrimal, nasocilliary.

Infraorbital (orbital floor fractures can damage, sense for lower eyelid and cheek), superior alveolar nerves (deeper structures like gum,teeth,nasal cavity,nasopharyngeal)

Inferior alveolar nerve exits bony mandible as mental nerve (mental protuberance/lower lip and gum) susceptible in mandibular fractures.
Lingual (ant tongue) and auriculotemporal (ear, temple area and tmj)

Question 28

Route of Abducens nerve?

Type and role?

Presentation and how damaged?

Answer 28

Lower pons (junction with medulla), through cavernous sinus and through superior orbital fissure.

Purely motor, one extra ocular muscle (lateral rectus).

Diplopia from micro vascular complication (diabetes and hypertension)

Question 29

What cranial nerves run through cavernous sinus?

Answer 29

1,3,4,6,maxillary