1. Auditory

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

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

4. 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

5. 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

6. 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

7. 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

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

9. Cochlear Duct

11. 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