Neuroanatomy of Audition Flashcards
Name the three main subdivisions of the ear and parts contained in each:
External: Pinna (Auricle), External auditory Meatus
Middle: Tympanic Membrane, Ossicles (Maleus, Incus, Stapes)
Inner: cochlea
Name the three compartments of the cochlea and the type of media contained in each:
Scala Vestibuli (Perilymph), Scala Media (Endolymph), Scala Timpani (Perilymph)
What structure secretes endolymph in the cochlea?
Stria vascularis
Name the three membranes significant to audition in the cochlea:
Tympanic membrane, basilar membrane, reissner’s membrane
What is the purpose of the row of inner hair cells? Outer hair cells?
Inner hair cells are responsible for hearing sensations, outer hair cells control amplification or dampening.
Describe the mechanism by which hair cells depolarize.
Adjacent stereocilia are linked together by tip links so they all bend when the endolymph shifts. Any movement toward the kinocilium (tallest projection) depolarizes the hair cell. Movement away from the kinocilium closes the ion channel. This gating is controlled by the tip links.
What ion(s) cause depolarization of hair cells?
K+ and Ca++
Once sound frequencies have been encoded by the hair cells in the cochlea, where is the information sent?
Hair cells synapse with C.N. VIII which sends information to the cochlear nuclei in the brainstem.
Give a description of the acoustic reflex:
Vibrations of ossicles are dampened by the tensor tympani (innervated by C.N. V) and the stapedius (innervated by CN VII). The superior olive controls these outputs by projecting to the trigeminal nucleus and facial nucleus in response to loud sounds.
Give the pathway for the dorsal and intermediate stria pathways:
CN VIII to dorsal cochlear nucleus. Crosses midline and ascends in the lateral lemniscus to terminate in the inferior colliculus.
Give the pathway for the dorsal and intermediate stria pathways:
CN VIII to dorsal cochlear nucleus. Crosses midline and ascends in the lateral lemniscus to terminate in the inferior colliculus.
Give the pathway for the dorsal and intermediate stria pathways:
CN VIII to dorsal cochlear nucleus. Crosses midline and ascends in the lateral lemniscus to terminate in the inferior colliculus.
Give the pathway for the ventral stria pathway:
CN VIII to ventral cochlear nucleus, some fibers cross midline (others stay ipsi) and ascends through the lateral lemniscus to the superior olive, nucleus of the lateral lemniscus and inferior colliculus.
Give the pathway for the ventral stria pathway:
CN VIII to ventral cochlear nucleus, some fibers cross midline (others stay ipsi) and ascends through the lateral lemniscus to the superior olive, nucleus of the lateral lemniscus and inferior colliculus.
Give the pathway for the ventral stria pathway:
CN VIII to ventral cochlear nucleus, some fibers cross midline (others stay ipsi) and ascends through the lateral lemniscus to the superior olive, nucleus of the lateral lemniscus and inferior colliculus.
