cranial nerves Flashcards
how many pairs of cranial nerves are there?
12
what different types of fibres can cranial nerves contain?
somatic motor fibres visceral motor fibres visceral sensory fibres general sensory fibres special sensory fibres
what do somatic motor fibres supply?
striated muscle
what do visceral motor fibres supply?
smooth muscle and glands
what do visceral sensory fibres receive input from?
pharynx larynx heart lung gut
what do general sensory fibres receive afferent inputs from?
afferent inputs (touch, temperature, pain) from skin and mucous membranes
where are the cell bodies for sensory fibres located?
outwith the CNS
where are the cell bodies for somatic motor fibres located?
inside the CNS
where are the cell bodies for autonomic motor fibres located?
within the CNS and outwith the CNS at synapses
what is cranial nerve 1 and what is its function?
olfactory - sensory (smell)
what is cranial nerve 2 and what is its function?
optic - sensory (vision)
what is cranial nerve 3 and what is its function?
oculomotor - motor (eye movement)
what is cranial nerve 4 and what is its function?
trochlear - motor (eye movement)
what is cranial nerve 5 and what is its function?
mixed - (sensation from face & mouth, muscles of mastication)
what is cranial nerve 6 and what is its function?
motor (eye movement)
what is cranial nerve 7 and what is its function?
mixed (muscles of facial expression, parasympathetic, taste)
what is cranial nerve 8 and what is its function?
vestibulocochlear - sensory (hearing and balance)
what is cranial nerve 9 and what is its function?
glossopharyngeal - mixed (swallowing, sensation from tongue, parasymp.)
what is cranial nerve 10 and what is its function?
vagus nerve - motor (soft palate, throat and neck)
what is cranial nerve 11 and what is its function?
motor - (soft palate, throat and neck)
what is cranial nerve 12 and what is its function?
motor- tongue
what is the pathway of the olfactory nerve?
olfactory nerve fibres pass through foraminifera in cribriform plate of ethmoid bone and enter olfactory bulb in the anterior cranial fossa
what can a fractured cribiform plate result in with regards to the olfactory nerve?
tear in olfactory nerve resulting in anosmia
what is the pathway of the optic nerve?
enters via optic canal, nerves join to form optic chiasm, fibres from medial (nasal) half of each retina cross to form optic tract
what is the pathway of the oculomotor nerve?
emerges from midbrain and exits via superior orbital fissure
what are some clinical signs that the oculomotor nerve may be damaged?
ptosis
eyeball abducted and pointing down
no pupillary reflex
no accomodation of the lens
what is the pathway of the trochlear nerve?
emerges from dorsal surface of the mid brain and exits via the superior orbital fissure
what is the pathway of the abducent nerve?
emerges between pons and medulla and exits exits via the superior orbital fissure
what are some clinical signs of trochlear nerve damage?
diplopia when looking down
what are some clinical signs of abducent nerve damage?
medial deviation of the affected eye causing diplopia
what is the pathway of the opthalmic nerve (V1)
emerges from the pons, travels through the trigeminal ganglion and exits via the superior orbital fissure
what is the pathway of the maxillary nerve (V2)
emerges from the pons, travels through the trigeminal ganglion and exits via the foramen rotundum
what is the pathway of the mandibular nerve (V3)
emerges from the pons, travels through the trigeminal ganglion and exits via the foramen ovale
what are some clinical signs of trigeminal nerve damage?
paralysis of muscles of mastication
loss of corneal or sneezing reflex
loss of sensation in the face
trigeminal neuralgia
what is the pathway of the facial nerve?
emerges between pons and medulla and exits via internal acoustic meatus, facial canal and stylomastoid foramen
what are some signs of facial nerve damage?
Bell’s palsy - cannot frown, close eyelid, or bare teeth
what is the pathway of the vestibulocochlear nerve?
emerges from between pons and medulla and exits via internal acoustic meatus, dividing into vestibular & cochlear nerves
what are some signs of vestibulocochlear nerve damage?
tinnitus (ringing in the ears)
deafness (conductive vs sensorineural)
vertigo (loss of balance)
nystagmus (involuntary rapid eye movements)
what is the pathway of the glossopharyngeal nerve?
emerges from medulla and exits via jugular foramen
what are some signs that the glossopharyngeal nerve has been damaged?
loss of gag reflex and taste from back of tongue
associated with injuries to CNs X and XI - jugular foramen syndrome
what is the pathway of the vagus nerve?
emerges from medulla and exits via jugular foramen, then everywhere
what are some signs that the vagus nerve has been damaged?
emerges from medulla and exits via jugular foramen, then everywhere
what is the pathway of the accessory nerve?
small cranial (medulla) and large spinal roots exit via jugular foramen
what are some signs that the accessory nerve has been damaged?
weakness in turning head and shrugging shoulder
what is the pathway of the hypoglossal nerve?
emerges from medulla and exits through the hypoglossal canal
what are some signs that the hypoglossal nerve has been damaged?
causes paralysis & atrophy of ipsilateral half of tongue. Tip deviates towards affected side
