CRANIAL NERVES Flashcards
which cranial nerves arise from the cerebrum, while the rest arise from the brainstem?
I and II
describe the olfactory nerve
- CN I
- sensory - SVA
- special sense of smell
- attaches directly to forebrain and is extremely short
what are olfactory nerve fibres capable of?
regeneration
what is the olfactory nerve derived from embryologically?
olfactory placode ( a thickening of the ectoderm)
the olfactory nerves terminate in the olfactory bulb, by synapsing on what cells?
mitral cells
what kind of neurons are olfactory receptor cells?
bipolar
what are basal cells?
form new stem cells from which the new olfactory cells can develop
describe the lateral and medial stria
- Lateral stria – carries the axons to the primary olfactory cortex, located within the uncus of temporal lobe.
- Medial stria – carries the axons across the medial plane of the anterior commissure, where they meet the olfactory bulb of the opposite side.
where does the olfactory nerve leave the skull?
cribiform plate of the ethmoid
describe the optic nerve
> sensory
SSA
special sense of vision
attaches directly to forebrain
what is the optic nerve enveloped in?
meninges and CSF
what is papilloedema
sweeling/oedema of the optic nerve
- raised intracranial pressure givers rise to this as the optic nerve is enveloped in the meninges and CSF, therefore if the intracranial pressure increases CSF is pushed out into the eye
where does the optic nerve enter the skull?
optic canal
what modalities to CN III/IV/VI possess?
all motor, covering GSE
oculomotor also conveys GVE
where do CN III/IV/VI enter the skull?
superior orbital fissure
what does CN III do?
- provides motor innervation to 4 extraocular muscles — superior, inferior and medial rectus, and the inferior oblique
- also has parasympathetic fibres — synapse at ciliary ganglion and innervate the levator palpebrae superioris muscle (elevates eyelid)
CN III : motor neurons that serve the extraocular muscles have cell bodies where?
oculomotor nucleus
CN III : the preganglionic parasympathetic neurons that supply the levator muscle arise from where?
Edinger-Westphal nucleus
CN III/IV/VI pass in the lateral wall of what?
the cavernous sinus
what does CN IV do?
provides motor innvervation to the superior oblique
where are the cell bodies of CN IV?
trochlear nucleus
what is the only cranial nerve to emerge from the dorsal aspect of the brainstem?
CN IV (emerges just caudal to the inferior colliculus)
what does CN VI do?
provides motor innervation to the lateral rectus muscle