Neuro Special Sensory Flashcards
What are the three semicircular canals?
Anterior
Posterior
Lateral (horizontal)
Where are the sensory cells found in the semicircular canals?
Ampulla
When the head moves to the right, which way will the hair cells bend in the ampulla?
Will bend to the left
When the endolymph moves in one direction, the vestibular nerve is stimulation and tells the brain the head is moving in the ______
Opposite direction
What is the area where sensory hair cells in the cochlea reside?
Organ of Corti
Where are sounds with low frequency heard?
Apex
Where are sounds with high frequency heard?
Base
What is the round window?
The relief valve for fluid coming through the cochlea
Where do ossicles articulate with the cochlea?
At the oval window
Where do auditory pathway fibers enter at?
The medulla
Where is the lateral lemniscus pathway (auditory) going?
From the brainstem to the medial geniculate nucleus in the thalamus
What is part of the reflex center for auditory sensation, activates by having fibers descend down the spinal cord to turn head towards loud noise.
Inferior coliculus
What tract sends signals from the inferior colliculus down the spinal column for a head turn reflex?
Tectospinal tract
In the auditory pathway, after going to the medial geniculate nucleus, what lobe do the fibers go to?
Temporal lobe at transverse gyrus (where auditory sensation first comes to conscious appreciation)
From what ear to the right hemisphere is there more input to the auditory cortex?
Left ear
What type of hearing loss is the result of a mechanical transmission problem from the middle ear structures?
Conductive hearing loss
What is neural hearing loss due to?
Destruction or degeneration of the portion of the Organ of corti or Vestibulocochelar nerve
What hair cells are initially lost in neural hearing loss?
Those that get rid of extra sounds. Makes this more difficult to hear in a noisy environment
Do patients usually detect a hearing loss with a brainstem lesion involving the auditory pathway?
No, because of the crossed and uncrossed nature of the pathway
Which is the dominant auditory cortex?
Left superior temporal gyrus
What does a lesion in the left superior temporal gyrus result in?
Inability to understand own spoken language (sensory aphasia))
What would a lesion in the non-dominant (right) auditory cortex result in?
Diminished ability to locate the source and direction of sound (but won’t be deaf)
Where do input from the vestibular system go (3 places) ?
Cerebellum (via inferior cerebellar peduncle) Spinal cord (vestibulospinal tracts) Nuclei that regulate eye movements (Via medial longitudinal fasiculus)
What facilitates the anti-gravity muscles?
Vestibulospinal tract
What is the organizing center for directing your eyes in a particular direction. It surrounds the abducens nucleus.
PPRF (paramedial pontine reticular formation)
What two structures does the medial longitudinal fasiculus connect?
Connects the vestibular path with the ocular nuclei
If you move your head to the right, your eyes conjugately move to the ___?
Left
What is oscillating, conjugate, slow movement of eyes in one direction followed by a rapid movement in the opposite direction. Normal response to head movement or moving visual target.
Nystagmus
Which semicircular canal is very close to the tympanic membrane?
lateral semicircular canal
Putting cold water into the external auditory canal causes a nystagmus in which direction?
Opposite direction
Putting warm water into the external auditory canal causes a nystagmus in which direction?
Same direction
What is a general term that refers to a lesion in the medial longitudinal fasiculus?
Internuclear opthalmoplegia
affected eye unable to adduct when other eye moves laterally
What are the three layers of the eye from inner to outer?
Retina
(pigmented epithelium)
Choroid (vascular)
Sclera (connective)
What is the pupil?
A hole
Where is your vision focussed all the time?
Fovea
The retina is a ___ neuron chain?
Three
What neuron’s axons form the optic nerve?
Ganglion neurons
What do the pigmented epithelium provide to the rods and cones?
Nutrients (via diffusion)
Surrond light sensitive tip so only that particular rod or cone is activated
Why do the rods and cones need nutrients via diffusion?
They are avascular
Rod and cones are continually ____
Renewed
Where is the only place where the retina is attached?
Optic disk near the cilliary muscle.
When a retina is detached from the choroid, what makes it worse?
Fluid or blood accumulation
Worse in the macula
Do the layers of the retina extend into the fovea?
No- it’s only the rods and cones that are in the fovea
If there is an increase in the ICP, where is the pressure also exerted and what does it lead to?
On the back of the eyeball
Can occlude blood vessels
Leads to papilledema
What chamber is the filtration (irdial) chamber located in?
Anterior
What constantly produces the aqueous humor?
Ciliary body epithelium (in posterior chamber)
How does aqueous humor get to the anterior chamber and then to be drained?
Through the pupil into anterior angle then into filtration angle
What does the ciliary body do?
Causes lens to increase/ decrease in anterior/ posterior direction (accommodation)
What chamber is the ciliary body in?
Posterior chamber
Parasympathetic innervation causes the pupil to: _______
Constrict
Sympathetic innervation causes the pupil to ____
Dilate
What is the most refractive structure in the eye?
Cornea
What is the difference between open and closed angle glaucoma?
In close angle there is a physical structure that is causing glaucome
Do the nasal or temporal retinal fibers cross?
Nasal
What would a lesion in the optic chiasm result in?
Bitemporal hemianopsia
nasal fibers can’t cross
What type shape is the retina?
Bowl-shaped
What makes up the right visual field?
Temporal fibers from the right eye
Nasal fibers from the left eye
If you have a lesion in the left retina or left optic nerve, where will you have blindness?
Left eye
If you have a lesion in the optic chiasm, what will happen
Bitemporal hemianopsia
Temporal parts of visual fields are lost because nasal parts are responsible for temporal visual field, and they are unable to cross
What does a lesion in the optic tract cause?
Homonoymous hemianopsia
Contralateral part of the visual field is lost
Where do neurons from the eyes synapse in the cortex initially ?
Lateral geniculate nucleus
Where do visual fibers end?
Medial aspect of the occipital lobe
The upper part of the left visual cortex sees…..?
Lower part of the right visual field
If an individual has a quadrantanopias in the right upper eye, where is the lesion most likely?
The left lower aspect of the temporal cortex
What artery supplies the visual cortex?
Posterior cerebral artery
Where is your interpretation of what you see occurs (lobes)?
Parietal lobe
Base of temporal lobe
What artery supplies the visual association areas (temporal and parietal lobes)?
Middle cerebral
What part of the visual association area interprets “where, how big, how far, motion”
Parietal lobe (superior)
What part of the visual association area interprets “what, name, form, color”
Ventral surface of temporal lobe
What are the two types of eye fields found in the cortex?
Frontal eye field
Parietal eye field
Which eye field is continually generating saccades and searching for a target?
Frontal eye field
Which eye field follows a target (ex- bird flying through air) ?
Parietal eye field
Which CN provides parasympathetic innervation to the eye?
oculomotor nerve (III)
What is the light reflex center of the brain?
Pretectal area (connect to CN III on both sides) Allows for consensual response
What pathway activates the sympathetic innervation to the dilator?
pretectal area
If the there is a lesion in a right optic nerve, and you shin a light in the left eye, will the right even respond by constricting?
Yes
Oculomotor nerve to right eyes is not damaged, so it will still show indirect response
If you have a right oculomotor lesion and you shine light in the eye, will the right eye constrict? What about the left?
Right eye will not constrict because the oculomotor nerve is not working (constrictor can’t be activated)
Fibers still get through to midbrain so left eye will constrict (consensual response)
Innervation of the dilator of the pupil is a _______ function.
Sympathetic
How does sympathetic nervous input get to the eye to tell it to dilate?
Pretectal area send axons down through brainstem into upper spinal cord where they synapse on preganglionic neurons which then synapse on a second neuron to stimulate the dilator
What happens as a result of a lesion into the sympathetic control of the pupil?
Horner’s syndrome (small pupils, ptosis, diminished sweating, vasodilation)
What is anhidrosis?
Diminished sweating
Sensation from the cornea is supplied by what nerve?
Trigeminal
Activation of the orbicularis oculii is by what cranial nerve?
Facial (VII)
Activation of the corneal response happen by input from the cornea by way of CN ___ and output to the _______ by way of the facial nerve?
CN V (trigeminal) orbicularis oculii
What CN opens the eye?
Oculomotor (III) innervating levatator palpebrae
Which CN closes the eye?
Facial (VII)
What is an arterio-venous malformation?
Tangle of abnormal vessels
What would atrophy of the left medial occipital lobe lead to?
Right homonymous hemianopsia
Activation of the orbicularis oculii is by what cranial nerve?
Facial (VII)
Activation of the corneal response happen by input from the ______ by way of the cornea and output to the _______ by way of the facial nerve?
cornea
orbicularis oculii
What CN opens the eye?
Oculomotor (III) innervating levatator palpebrae
Which CN closes the eye?
Facial (VII)
