GIẢI PHẨU TAI

THE UNIVERSITY TRAINING CENTER FOR HEALTH CARE PROFESSIONALS OF HCMC DEPARTMENT OF ANATOMY THE EAR Lecturer KHOA TRAN DANG, M.D THE EAR Ludwig van Beethoven (1770-1827) th Symphony (Choral) Composed when he was profoundly deaf 29 june 1801 THE EAR Outer ear Middle ear Inner ear Four major divisions of auditory system – Function THE EXTERNAL EAR THE EXTERNAL EAR THE EXTERNAL EAR   Three parts of outer ear 1) Pinna 2) Ear canal 3) Ear drum Major function of outer ear 1) protection 2) amplification 3) sound localization I Outer ear: THE EXTERNAL EAR (1) Pinna (Binaural cue to sound source location) Sound t Right t Left Right ear Left ear * Different distances from source to each ear => different arrival times (Interaural time-difference) and different sound level (interaural level-difference) THE EXTERNAL EAR I Outer ear: Outer ear gain (1) Pinna (Spectral cue to sound source location) +15° 0° -15° The spectral feature of sound is changed depending on the sound elevation => Head Related Transfer Function (HRTF) THE EXTERNAL EAR I Outer ear (1) Pinna: Cases of abnormal pinna   Anotia Microtia (Grade II)   Microtia (Grade I) Microtia (Grade III) THE INNER EAR How you protect yourself? Ear Plugs Wear WearThem! Them! THE MIDDLE EAR ↓ten tymp mem ↓p perilym VII ten tymp mem ↑p perilym V3 NERVE for muscles in tymp cav THE MIDDLE EAR THE MIDDLE EAR VESTIBULAR NERVE Mechanisms of Equilibrium and Orientation Vestibular apparatus – inner ear equilibrium receptors in the semicircular canals and vestibule (maintains orientation and balance) Two functional groups of receptors: Vestibular receptors (maculae) monitor static equilibrium Semicircular canal receptors (cristae) monitor dynamic equilibrium Maculae - Static Equilibrium Each macula is a flat section of epithelial tissue containing supporting cells and hair cells Each hair cell has stereocilia (microvilli) and a kinocilium embedded in the otolithic membrane Otolithic membrane is a jellylike mass containing tiny CaCO3 stones (crystals) called otoliths Utricular hairs respond to horizontal movement Saccular hairs respond to vertical movement Anatomy of Maculae Otolithic movement in one direction depolarizes vestibular nerve fibers and increases the number of action potentials generated Movement in the opposite direction hyperpolarizes vestibular nerve fibers and reduces the rate of impulse propagation The maculae respond only to changes in head position Crista Ampullaris - Dynamic Equilibrium The crista ampullaris (or crista) is located in the ampulla of each semicircular canal and responds to angular movements Each crista has support cells and hair cells that extend into a gel-like mass called the cupula Dendrites of vestibular nerve fibers encircle the base of the hair cells Crista Ampullaris Cristae respond to changes in velocity of rotatory movements of the head Directional bending of hair cells in the cristae causes either depolarizations (rapid impulses) or hyperpolarizations (fewer impulses) Impulses in the vestibular nerve component of cranial nerve VIII travel to the vestibular nuclear complex (brain stem) or the cerebellum - responses are reflexive VESTIBULAR NERVE VESTIBULAR NERVE VESTIBULAR NERVE THANK YOU FOR YOUR ATTENTION ! All details, please contact me: Website: www.drkhoatran.com Email : khoatrandr@yahoo.com / contact@drkhoatran.com Office phone : 8632-824 Cellular phone : 0989-675901