HS133: The Ear 2024 PDF

HS133: The ear Prof. Rachael-Anne Knight [email protected] With thanks to María Miranda Rivera and Analisa Marie Pais Functions of the ear The ear has two main functions Hearing Balance https://www.youtube.com/watch?v The ear Divided into three areas Outer ear...

HS133: The ear Prof. Rachael-Anne Knight [email protected] With thanks to María Miranda Rivera and Analisa Marie Pais Functions of the ear The ear has two main functions Hearing Balance https://www.youtube.com/watch?v The ear Divided into three areas Outer ear Middle ear Inner ear Effective functioning of these areas is essential for normal hearing The auditory nervous system must be intact for sound to be transferred and interpreted Regions of the ear Outer ear: structures and functions Auricle (pinna) – Most visible part of the ear – Acts as funnel and directs sound further into the ear – Helps localize sound – Conchae: Resonating cavity Ear canal (external auditory meatus) – From concha to eardrum – Transmits sound from the pinna to the eardrum – 1/3rd cartilaginous, 2/3rd bony meatus – Resonating cavity Tympanic membrane (eardrum) Tympanic membrane Tympanic membrane (eardrum) – thin, elastic, flattened-cone shaped membrane At the end of the auditory canal Three layered tissue comprising an external epithelial lining of the outer ear canal, a think fibrous tissue in between and an internal mucosal epithelial lining of the middle ear. Vibrates in response to pressure from sound waves Easily damaged  Middle ear – structures and functions Air filled cavity Between eardrum (tympanic membrane) and oval window Ossicular chain Malleus (hammer) Incus (anvil) Stapes (stirrup) (4mg) Eustachian tube Oval and round windows  Ossicular Chain (bones of the middle ear) Transmits sound efficiently and with no distortion Amplifies incoming sound before transmitting it into the fluid in the inner ear Oval and round windows – two openings to the cochlea in the inner ear - Foot plate of stapes embedded in oval window - Round window sealed by the secondary TM  Eustachian Tube (auditory/ pharyngotympanic tube) Connects middle ear to nasopharynx Aeration— bringing O2 to the middle ear Maintain equal air pressure within and outside the middle ear Can allow germs and infections to spread into the middle ear -> hearing problems Inner ear Houses sensors for balance (vestibular system) and hearing (cochlea) Inner ear receives mechanical vibrations of sound through the movement of the stapes in Two major structures: semicircular canals and the oval window cochlea (Roseberry-McKibbin, Hedge, 2016, Seikel et al, 2010) Semicircular canals Part of the vestibular system Vestibular system – provides sense of balance and information about the body’s position Responsible for equilibrium Three fluid filled tubes Contain hair cells that detect movement in the fluid and send impulses to the brain Brain decodes this and helps body The cochlea Small fluid filled spiral in the temporal bone Sound waves transmitted from the oval window are transmitted to the fluid in the cochlea Basilar membrane – tissue within the cochlea containing thousands of cilia (hair cells) which respond to sound Transduce movement into electrical signals The basilar membrane responds different to different frequencies due to differences in thickness, width and stiffness along its length The basilar membrane The basilar membrane contains the Organ of Corti In turn the Organ of Corti contains a single row of inner hair cells, and 3+ rows of outer hair cells The hair cells turn vibration into electrical impulses in the auditory nerve which travel to the brain Action of the hair cells https://www.youtube.com/watch?v=K-cRIO4gQmk&ab_channel=StoriesfromtheEast  Let’s take a tour of the ear! (no sound) https://www.youtube.com/watch?v=yL_17sfMKMs&ab_channel= AllisonBradley Ear Anatomy and Physiology Activity Divide yourself into groups of 8 1.Pinna 2.Ear canal 3.Tympanic membrane Number yourselves 1-8 4.Malleus 5.Incus Each person describes the role of a part 6.Stapes of the ear, as shown by the numbers on the right 7.Cochlea Your aim as a group is to be able to 8.Auditory nerve describe the process of hearing in about 5 minutes (40 seconds for each (cochlea nerve) person/part) Quiz Let’s review our knowledge on poll everywhere. PollEv.com​/rak Physiology of Hearing- Video http://www.youtube.c om/watch?v=46aNGG NPm7s&list=PL929D3 17C1281E05B  Hearing summary https://www.youtube.com/watch?v=flIAxGsV1q0&ab_channel=MED-EL Clinical note With usual caveat that RAK is not a clinician Can you think of any conditions relating to the ear and its relevance to SLT? Clinical note Hearing impairment – damage to one or more parts of the ear. Most common cause in children is otitis media (ear infection in the middle ear), commonly associated with with upper respiratory infection e.g. cold Malformations of the pinna (e.g., apasia, microtia), or the EAM (e.g., atresia, stenosis) Vertigo – feeling of dizziness or whirling in space Tinnitus – ringing sound in the ears can result as consequence to loud noise exposure, medications, wax build-up or varies disturbances of the auditory nerve What do you think would be the role of the SLT working with children with hearing impairment? See the RCSLT position statement on Deafness and SLT  Tour of the ear & impact of HAs https://www.youtube.com/watch?v=vn8r55mlaMo&ab_channel= BeltoneHearingGlobal Summary of the Ear, Nose and Throat: Endoscopic