Auditory

Equilibrium & Soundwave Detection Equilibrium  gives information about position of head Hearing  detect and interpret sound waves Auditory receptors are called hair receptors

Anatomy of Ear External  directs soundwaves to middle Middle  directs soundwaves to inner Inner  contains sensory organs for sound detection and equilibrium

External Ear Pinna, auricle – funnels sound waves into external acoustic meatus  tympanic membrane (eardrum) Ceruminous glands – prevent dust and debris from entering the middle ear Secretes a waxy substance to trap the dust and debris

Middle Ear AKA tympanic cavity Connected to the back of the upper throat by the auditory tube Contains 3 auditory bones (auditory ossicles) Sound vibrations  malleus  incus and stapes  pushes on the oval window (inner ear)  stimulate auditory receptors Tiny muscles – tensor typani and stapedius Smallest skeletal muscles on the human body Prevent damage to tympanic membrane and ossicles during loud sounds

Inner Ear Cochlea – receptors for hearing Vestibule – receptive to static equilibrium Saccule & Utricle Semicircular canals – receptors for “dynamic equilibrium” (when body moves) Contain semicircular ducts that have a swollen ampulla that houses the balance receptors called cristae

Inner Ear – Cochlea 3 ducts in a spiral formation – chochlear duct Contains hair cells that are sensitive to vibrations Contains sensory receptor, organ of Corti Vestibular duct and tympanic duct - filled with perilymph Basilar membrane – where hair cells occur

Hearing Auditory ossicles convert pressure from air into pressure in the perilymph This stimulates the hair cells Frequency vs intensity?

Cochlear Duct

https://www.youtube.com/watch?v=qgdqp-oPb1Q

Review Soundwaves arrive at tympanic membrane Auditory ossicles are displaced Movement of the stapes at oval window  creates pressure on the scala vestibuli Pressure waves distort the basilar membrane to get to round window of scala tympani Vibration of basilar membrane causes hair cells to vibrate – displacement of cells leads to a depolarization event! Cell bodies located within the spiral ganglion of the cochlea transmit the information