Cranial Nerves Flashcards
Is the optic nerve (CNII) sensory or motor?
Sensory
What is CN III?
The Occulomotor nerve
What is CN II?
Optic Nerve
What are the 2 cranial nerves that the midbrain beholds?
- Occulomotor nerve (CN III)
- Tochlear nerve (CN IV)
(both are motor)
Is the trigeminal nerve (CN V) sensory or motor?
Both
Where is the trigeminal nerve (CN V) located?
Pons
The pontomedullary junction holds what 3 cranial nerves?
- Abducens CN VI
- Facial CN VII
- Vestibulocochlear CN VIII
Is the abducens CN VI sensory or motor?
Motor
Is the Facial nerve CN VII sensory or motor?
Both
Is the vestibulocochlear CN VIII sensory or motor?
Sensory
What cranial nerves stem from the medulla?
- Glossopharyngeal CN IX
- Vagus nerve (X)
- Hypoglossal nerve (CN XII)
Is the glossopharyngeal cranial nerve sensory, motor or both?
Both
Is the vagus nerve CN X sensory or motor?
Both
Is the hypoglossal CN XII sensory or motor?
Motor
What are the midbrain’s key roles?
- Visual system
- Accommodation reflex (e.g. optic sensory nerve in and oculomotor nerve out)
- Pupillary light reflex (e.g. constriction/dilation)
- Contains substantial nigra
- Dopaminergic system (movement/behaviour)
What 4 reflexes are associated with the pons?
- Jaw-jerk reflex (trigeminal)
- Corneal-blink reflex (facial-trigeminal)
- Tensor tympani stapedius reflux
What are the medulla oblongata reflexes associated with?
- Swallowing & gag reflex (glossopharyngeal + vagus)
- Cough
- Sneeze
- ## Sight of decussation of many neurons
Reticular formation in the midbrain is associated with what?
- Wakefulness (circadian rhythm)
- Consciousness
Are somatic motor fibres associated with voluntary or involuntary muscles?
Voluntary
How many cranial nerves are there?
12
What are the 5 types of cranial nerve fibres?
- Somatic motor fibres
- Visceral motor fibres
- General visceral sensory
- General somatic sensory
- Special sensory afferents
What is CN I and what is it associated with?
- Olfactory nerve
- Special sensory (smell)
Where does the olfactory nerve (CN I) originate?
They originate at the chemoreceptors of olfacotyr epithelium
Where does the olfactory nerve (CN I) enter the cranium?
m through foramina
of cribriform plate of the ethmoid bone
What is the only cranial nerve to attach directly to the cerebrum?
The olfactory nerve (CN I)
What is the second cranial nerve (CN II)?
Optic nerve
What is the estimated number of fibres does the optic nerves contain?
Est. 1 million
What location does the optic nerve (CN II) have a partial crossover after it moves through the optic canal?
optic chiasm
Where does the optic nerve (CN II) terminate?
in lateral
geniculate nucleus, (LGN)
In the thalamus
What is the name of cranial nerve III (CN III)?
Oculomotor nerve
What is CN III associated with?
chief motor nerve to ocular and extraocular muscles (eye muscles)
Where does the oculomotor nerve originate?
Midbrain (mesencephalon)
What type of fibres does the oculomotor nerve comprise?
Both somatic and visceral motor fibres
How many oculomotor nuclei is in the mesencephalon?
2
What are the 4 somatic motor fibres of the eye does the oculomotor nerve supply?
superior rectus
* medial rectus
* inferior rectus
* inferior oblique
- What 3 things do the VISCERAL oculomotor nerves supply?
- parasympathetic innervation of
eye via ciliary ganglion - smooth muscle of pupil
(sphincter pupillae) –
constriction - ciliary body -accommodation
(change in lens shape)
What is the cranial nerve IV? and what is it associated with?
- Trochlear nerve
- innervates the superior oblique muscle of the eye
Where does the trochlear nerve originate?
dorsal mesencephalon
What cranial nerve runs the longest intracranial course?
- Trochlear nerve (CN IV)
What mechanism does the (CN IV) trochlear nerve innervate the superior oliquie extraocular muscle of the eye?
- A pully mechanism