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Flashcards in Neuro Deck (155)
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121

What is the superior colliculus?

Mesencephalic laminated structure
receives input primarily from parasol cells
involved in controlling eye muscles and orienting reflex

122

What si damage of V5/MT resulting in?

Associated with an impairment in the detection of motion.

123

What happens when V4 is damaged?

cerebral achromatopsia

124

What is the Pinna?

The eterior of the ear that channels and filters sound to external canal, amplifies freq @ 3000 Hz

125

What is the structure of the tympanic membrane?

3 layer translucent membrane, with 1 cm^2 vibratory surface

126

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

127

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

128

How does the cochlea determine pitch?

Position of maximum wave on basilar membrane in cochlea

129

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

130

What are the two types of hearing losss?

Conductive adn sensorineural

131

How does sensorinerual occur?

congenital
noise exposure/trauma
medication
age

132

What is the main region for auditory processing?

Heschel's Gyrus, A1 in the temporal region

133

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

134

What are the three parts of the vestibular apparatus?

Bony labyrinth
membranous labyrinth
sensory receptors

135

What detect linear acceleration in the inner ear?

Maculae in the utricle and saccule

136

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

137

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

138

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

139

What are the four vestibular nuclei?

Caudal Pons:
superior vestibular nucleus
Lateral vestibular nucleus
Rostral medulla:
Medial vestibular nucleus
Inferior vestibular nucleus

140

What is the role of the lateral vestibulospinal tract?

Maintains balance and posture on the ipsilateral side of the bodyu

141

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)

142

What does the vestibuloocular reflex do?

maintains eye postion during head movemnt

143

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

144

What is nystagmus?

rhytmic oscillations of eyeballs
temperature generated convection current causes them
observigna moving object causes tehm
rotation of the head causes them

145

What type of diziness is usually otologic?

verticgo
nystagmus specifically is uasually ear generated and casuses sensation of spinning

146

What si Ewalds first law?

Stimulation of a semicircular canal generates eye movement in the plane of the that canal

147

What are the three clinical mechanisms to uncover teh otological weakness ?

head thrust test
gaze evoked nystagmus
head shake teest

148

What is Alexander's law?

gaze in the direction of the fast phase of nystagmus increases amplitude and frequency

149

What is Ewalds second law?

excitatory responses for the VORare greater than inhib responses

150

What is superior canal dehiscence?

loss of bone covering over the superior canal, ecitation by various stimuli
tones
excercise
pressure