cranial nerve lesions Flashcards
what does the olfactory nerve sense
- sense of smell
- there is one nerve in each nostril
what does the optic, oculomotor, trochlear and abducens nerves do
- they give the sense of sight and the ability to move your eyes
- optic has neurons in your retina
how do the nerves to the eye travel
- optic, oculomotor, trochlear and abducens all converge to form the optic nerve
- they hemidecusate and cross over
- they synapse in the thalamus and travel posteriorly to the cortex
what is visual acuity
how easy it is to resolve something we are looking at
what happens in right monocular blindess
one sides optic nerve (past convergence) has been cut so there is full vision loss in that one eye
what happens in bitemporal hemianopsia
the nasal fibres are damaged so the lateral fields on both sides are lost
- the fibres closest to the nose are gone so peripheral vision is gone
what happens in left homonymous hemianopsia
one of the optic tracts has been damaged (before convergence). eg right damaged loses left side of both visual fields, as nasal fibres cross over but the other fibres don’t so one on each side is gone
what are the stages of the pupillary reflex
- light is detected by the retina
- signal is carried by the optic nerve
- processed in the brain stem
- impulse created in the parasympathetic nucleus of oculomotor
- travels along both oculomotor nerves
- synapse in ciliary ganglia
- travels to sphincter pupillae part of irises
- both pupils constrict
where does the trigeminal nerve give sensation to
separated into V1, V2, V3 from font of the ear forwards
what happens when there is damage to the trigeminal motor
- paralysis of muscles of mastication
- the mandible will move towards the effected side
- both motor and sensory will be affected
what are the stage of the corneal reflex
- touch to the cornea
- detected by trigeminal (V)
- signal is passed to facial nerve (VII)
- triggers the blink by activation of the orbicularis oculi muscle
what does the trigeminal nerve detect
meninges, sinus, inside of nose, roof and floor of mouth, skin on the face
what are the stages of the gag reflex
- detection of sensation at back of throat
- carried by glossopharyngeal nerves (IX)
- signal passed to vagus nerve
- gag - attempted regurgitation
how do you test for a change in accessory nerve
- sternocleidomastoid function by pashing face against hand
- test trapezius function by shrugging shoulders against force
what are the tongues innervations
- trigeminal to anterior 2/3
- glossopharyngeal to posterior 1/3
- hypoglossal for the muscle
- facial for the special sense taste
