Session 4 Flashcards
Where do cranial nerves arise from?
How many are sensory,motor,mixed?
The level of the brainstem
4 mixed, 3 sensory, 5 motor.
Role of the 3 sensory nerves?
Hearing and balance=VIII
Smell= I
Vision= II
What nerves form taste?
They are both mixed. VII and IX.
What 4 cranial nerves contain autonomic fibres?
III, VII, IX, X
How are cranial nerves numbered?
How they enter the brainstem from rostralmto caudal.
Name the 12 cranial nerves
I Olfactory II Optic III Oculomotor IV Trochlear V Trigeminal VI Abducens VII Facial VIII Vestibulocochlear IX Glossopharynx X Vagus XI Accesory XII Hypoglossal
What indicates an extradural haemorrhage? Ie history
Trauma,lucid interval,deterioration
What’s a subaponeurotic haemorrhage?
One on the scalp usually with superficial temporal artery
Presentation of subdural haemorrage?
Old, confused, bridging vein
Subarachnoid haemorrage presentation?
Increase BP, severe headache, aneurysm
What do all the mixed cranial nerves have in common?
They are all autonomics
What two nerves arise prior to the brainstem?
Olfactory and optic
Describe the route of the olfactory nerve
Type of nerve and function?
Name for loss of smell?
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.
Describe the route of the optic nerve?
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.
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)?
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.
How fair does the visual pathway with the optic nerve extend?
Why communication with optic tracts and brainstem?
From retina to occipital lobe
Allows certain reflexes e.g pupillary reflex to light.
2 nerves arising from midbrain?
Oculomotor and trochlear
Route of Oculomotor nerve?
Type of nerve fibres?
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)
Why is the Oculomotor nerve squashed if raised ICP?
How can you test the Oculomotor nerve?
Causes of pathology?
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.
Describe the route of the trochlear nerve?
Type of nerve and role?
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)
What cranial nerve has the longest route and where does it arise?
Consequences if this nerve is damaged?
The trochlear nerve arising from the dorsal aspect of the midbrain.
Diplopia from congenital palsies or raised ICP.
4 cranial nerves arising from the pons?
Trigeminal, Abducens, fascial, vestibulocochlear
Type of nerve and role of trigeminal?
Sensory and motor.
Sensory-main skin of face and scalp, deeper structures like nasal/oral cavity, meninges, paranasal air sinuses.
Motor-muscles of mastication.
What three sensory regions of the face does the trigeminal ganglion split into? And what fossa/fissure do they enter?
Ophthalmic-sup orbital fissure then into the orbit
Maxillary-foramen rotundum then pterygopalatine fossa
Mandibular-foramen ovale then infratemporal fossa
How would you test the muscles of mastication?
Jaw jerk which should give the corneal reflex
Worry if ophthalmic division of trigeminal nerve gets shingles?
It includes the eye itself can cause blindness
Branches of ophthalmic division of trigeminal?
Branches of maxillary?
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)
Route of Abducens nerve?
Type and role?
Presentation and how damaged?
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)
What cranial nerves run through cavernous sinus?
1,3,4,6,maxillary
