Week 7: Auditory, Vestibular, Olfaction, and Taste Flashcards
Membranous Labyrinth Contents
Endolymph
Endolymph Composition
High in K+, Low in Na+
Bony Labyrinth Contents
Perilymph
Perilymph Composition
Resembles extracellular fluid and CSF
Relationship of Membranous Labyrinth to Bony Labyrinth
Membranous labyrinth is suspended in the boney labyrinth
Action of Tectorial Membrane to Organ of Corti
Organ of corti moves in response to sound pressure, which causes its hair cells to brush against the tectorial membrane
Inner Hair Cell Anatomy
Single row innervated by up to 10 nerve fibers
Inner Hair Cell Function
Detection of frequency and fine discrimination of sounds
Outer Hair Cell Anatomy
3 to 4 rows but 1 nerve fiber for multiple cells
Outer Hair Cell Function
Efferent structures that modulate sensitivity of the organ of Corti by changing length in response to sound
Cochlear Frequency Organization
High to low down the length and spiral of the cochlea
Superior Olivary Nuclear Complex Function
Localizing sound in space
Location of Decussating Auditory Fibers
Trapezoid Body of Caudal Pons or Pontine Tegmentum
Blood Supply of Cochlear Nuclei
Anterior Inferior Cerebellar Artery
Primary Auditory Cortex Location
Anterior transverse gyrus of temporal lobe medial to superior temporal gyrus and viewed by opening the lateral fissure
Secondary and Higher Order Auditory Cortex Location
Belt around the primary cortex
Secondary and Higher Order Auditory Cortex Function
Activated by complex sounds
Vestibular System Gross Anatomy
Utricle, Saccule, 3 Semicircular canals
Utricle and Saccule Function
Linear acceleration and gravitational positioning
Semicircular Canals Function
Angular acceleration
Macula of Utricle and Saccule
patch of hair cells in each organ covered by otolithic membrane
Otolithic Membrane
Gelatinous patch covered by otoliths
Cupula of Semicircular Canals
Movement of endolymph against this structure causes hair cells within it to bend, which senses motion
Vestibular Pathways
- Medial Longitudinal Fasciculus
- Vestibulospinal Tract
- Vestibulocolic Pathways
- Vestibulothalamocortical
- Vestibulocerebellar
- Vestibuloreticular
Medial Longitudinal Fasciculus Vestibular Function
Bilateral connections with CN II, IV, VI, and superior colliculus, influencing eye movement
Vestibulospinal Tract Vestibular Function
Medial and lateral tracts to influence posture
Vestibulocolic Pathways Vestibular Function
CN XI nucleus, influencing head position
Vestibulothalamocortical Vestibular Function
Conscious awareness of head movements and positions, and input to corticospinal tract
Vestibulocerebellar Vestibular Function
Controls magnitude of muscle responses to vestibular information
Vestibuloreticular Vestibular Function
Influences autonomic centers for nausea and vomiting
Taste Nucleus
Rostral solitary nucleus
