Quesmed Eyes and Ear Flashcards
Weber’s Test lateralises to the right
Conductive hearing loss in right ear
OR
Sensineural loss in the left ear
What does Weber’s test appear louder in?
Ear with no sensineural hearing loss such as:
conductive hearing loss or normal hearing
Rinne’s test- positive
Normal ear where air conduction is better than bone
Rinne’s test- positive
Abnormality where bone conduction is better than air
Weber’s lateralises to the left ear but Rinne’s test is positive for both?
Right sensineural hearing loss
Rinne’s tests for CONDUCTIVE hearing loss
Which hearing test is more sensitive?
Weber test
How does high frequency sound affect the ear?
Base of the cochlea where membrane has high stiffness and low mass
How does gentamicin toxicity manifest?
Vertigo
Loss of balance
Ataxia
Where does sound travel after the oval window?
Through perilymph in the cochlea.
What is the perilymph?
Located in the scala vestibular and scala tympani. It is rich in sodium and low in potassium.
Which structure is responsible for tonotopy?
Basilar’s membrane, located between scala tympani and scala media.
Vibration of the Basilar membrane causes movement of stereocilia and opening of mechanically-gated ion channels to generate action potentials down the vestibulocochlear. Nerve
Which sound goes to the base of the Basilar membrane?
High frequency
Which sound goes to the apex of the Basilar membrane?
Low frequency
What is the role of Reisnner’s membrane?
Diffusion barrier for nutrients from perilymph.
What is the function of the middle ear muscles?
Primary function is to increase frequency of air kinetic energy to the level of the cochlear fluid.
What is characteristic frequency?
The characteristic frequency is the frequency at which the threshold for generating a nerve impulse is reached
Where do the auditory nerve fibres terminate?
Auditory nerve fibres terminate at the cochlear nucleus of the brainstem, between pons and medulla.
What is the role of inner hair cells of the ear?
Signal transduction.
What is the role of outer hair cells of the ear?
Non-linear amplification of sound
Anterior semicircular canal
Up and down movement, involved in protective reflex
Lateral semicircular canal
Tilting head side to side
Posterior semicircular canal
Left and right movement
Saccule
Vertical movement up and down
Utricle
Horizontal movement forwards and backwards
Low frequency sound travels here?
Helicotrema, between scala vestibula and scala tympani filled with perilymph rich in Na+
Where does decassation occur in auditory cortex?
Superior olivary nucleus, located in the pons
Medial geniculate nucleus of thalamus
What is the role of inferior olivary nucleus?
Located in medulla for visual information.
