Flashcards in Neuro Deck (155)
What is the superior colliculus?
Mesencephalic laminated structure
receives input primarily from parasol cells
involved in controlling eye muscles and orienting reflex
What si damage of V5/MT resulting in?
Associated with an impairment in the detection of motion.
What happens when V4 is damaged?
What is the Pinna?
The eterior of the ear that channels and filters sound to external canal, amplifies freq @ 3000 Hz
What is the structure of the tympanic membrane?
3 layer translucent membrane, with 1 cm^2 vibratory surface
What are the mechanisms used to amplify sound to overcome transfer of waves from air to sound?
Area ratio of tympanic membrane to oval window
lever action of the ossicular chain: malleus longer than incus
Buckling of the TM
What is teh mechansim of the basilar membrane mechanics?
The base is narrow and stiffer, vibrates more at high sounds
apex is wider and loose allowing for lower sound
How does the cochlea determine pitch?
Position of maximum wave on basilar membrane in cochlea
How do hair cilia work?
Endolymph has high K+ and hair have very low K+, tiplinks openwhen hair cells moved by acoustic energy, resulting in hyperpolarization, tip links linked by actin
What are the two types of hearing losss?
Conductive adn sensorineural
How does sensorinerual occur?
What is the main region for auditory processing?
Heschel's Gyrus, A1 in the temporal region
What are teh central auditory pathway?
VCN involved in localizing sounds
DCN involved in recognizing sounds
Nerve to medulla to pons to mibrain to thalamus to cortex
What are the three parts of the vestibular apparatus?
What detect linear acceleration in the inner ear?
Maculae in the utricle and saccule
How are hair cells depolarized in response to linear acceleration?
The stereocilia bundles are polarized towards a ridge and when deflection toward the kinocilium occurs it leads to cell depolarization
What is the ridge of sensory epithelium in the ampulla called?
Crista ampullaris, this senosry epithelium is covered by gelatinous material that makes up the cupola
Rotation of the head causes endolymph in the ampula to move this allows what?
THe semicircular canals, and endolymph pushes on teh sensosry epithelium in response to change in speed of head rotation
What are the four vestibular nuclei?
superior vestibular nucleus
Lateral vestibular nucleus
Medial vestibular nucleus
Inferior vestibular nucleus
What is the role of the lateral vestibulospinal tract?
Maintains balance and posture on the ipsilateral side of the bodyu
What is the role of the medial vestibulospinal tract?
adjusts head position in response to postural changes
coordinates eye movements, with head movements and each other
vestibuloocular reflex (VOR)
What does the vestibuloocular reflex do?
maintains eye postion during head movemnt
What si teh central pathway for VOR?
semicircular canals detect head movment and this sends to vesitbular nuclei
vestibular nuclei project to brainstem nuclei that control extraocular muscles
extraocular muscles contract moving eyes to maintain fovveattion
What is nystagmus?
rhytmic oscillations of eyeballs
temperature generated convection current causes them
observigna moving object causes tehm
rotation of the head causes them
What type of diziness is usually otologic?
nystagmus specifically is uasually ear generated and casuses sensation of spinning
What si Ewalds first law?
Stimulation of a semicircular canal generates eye movement in the plane of the that canal
What are the three clinical mechanisms to uncover teh otological weakness ?
head thrust test
gaze evoked nystagmus
head shake teest
What is Alexander's law?
gaze in the direction of the fast phase of nystagmus increases amplitude and frequency
What is Ewalds second law?
excitatory responses for the VORare greater than inhib responses