DOCSLIB.ORG

The Special Senses the Ear External Ear Middle

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Special Senses the Ear External Ear Middle 1/24/2016 The Ear • The organ of hearing and equilibrium – Cranial nerve VIII - Vestibulocochlear – Regions The Special Senses • External ear • Middle ear Hearing and • Internal ear (labyrinth) Equilibrium External Ear Middle Internal ear • Two parts External ear (labyrinth) ear – Pinna or auricle (external structures) – External auditory meatus (car canal) Auricle • Site of cerumen (earwax) production (pinna) – Waterproofing, protection • Separated from the middle ear by the tympanic membrane Helix (eardrum) – Vibrates in response to sound waves Lobule External acoustic Tympanic Pharyngotympanic meatus membrane (auditory) tube (a) The three regions of the ear Figure 15.25a Middle Ear Epitympanic Middle Ear Superior Malleus Incus recess Lateral • Tympanic cavity Anterior – Air-filled chamber – Openings View • Tympanic membrane – covers opening to outer ear • Round and oval windows – openings to inner ear • Epitympanic recess – dead-end cavity into temporal bone of unknown function • Auditory tube – AKA Eustachian tube or pharyngotympanic tube Pharyngotym- panic tube Tensor Tympanic Stapes Stapedius tympani membrane muscle muscle (medial view) Figure 15.26 1 1/24/2016 Middle Ear Middle Ear • Auditory tube (Eustachian tube) • Otitis Media – Connects the middle ear to the nasopharynx • Equalizes pressure – Opens during swallowing and yawning Middle Ear Middle Ear • Contains auditory ossicles (bones) • Sound waves cause tympanic membrane to vibrate – Malleus • Ossicles help transmit vibrations into the inner ear – Incus – Reduce the area where force is applied – Stapes – Increases the pressure of the force enough to transfer most of the • Middle ear is air-filled; inner ear is fluid-filled energy into the liquid – Reflexive muscle action • Sound is mostly reflected from a liquid medium restricts the movement of the bones during loud noises Inner Ear Superior vestibular ganglion Inferior vestibular ganglion • Contains functional organs for hearing & equilibrium Temporal bone –Bony labyrinth - filled with perilymph Semicircular ducts in Facial nerve –Membranous labyrinth – functional component semicircular canals Vestibular • Filled with endolymph nerve • Anterior Location of various Posterior inner ear receptors Lateral Cochlear Cristae ampullares nerve in the membranous Maculae ampullae Spiral organ Utricle in (of Corti) vestibule Cochlear duct Saccule in in cochlea vestibule Stapes in Round oval window window Figure 15.27 2 1/24/2016 Inner ear - Labyrinth Superior vestibular ganglion Inferior vestibular ganglion • Temporal Labyrinth is modified to form 3 distinct regions bone Semicircular –Vestibule ducts in Facial nerve semicircular • Gravity canals Vestibular nerve • Head position Anterior • Linear acceleration and deceleration (changes in speed) Posterior –Semicircular canals Lateral Cochlear • Angular acceleration and deceleration (changes in direction) Cristae ampullares nerve –Cochlea in the membranous Maculae ampullae • Spiral organ Vibration Utricle in (of Corti) vestibule Cochlear duct Saccule in in cochlea vestibule Stapes in Round * Note: It is always the membranous labyrinth that contains the receptors oval window window Figure 15.27 Inner Ear • The cochlea – A spiral, conical, bony chamber Modiolus Cochlear nerve, – Still 2 portions of bony labyrinth enclosing a portion of membranous division of the labyrinth Bony vestibulocochlear labyrinth nerve (VIII) Membranous Spiral ganglion labyrinth Osseous spiral lamina Vestibular membrane Bony labyrinth Cochlear duct (scala media) (a) Helicotrema Figure 15.28a Inner ear Vestibular membrane Osseous spiral lamina Tectorial membrane Scala Spiral • Cochlear duct vestibuli ganglion Cavity of the cochlea is divided into 3 chambers (scala media ; – (contains Vestibular canal (scala vestibuli) contains perilymph) • Vestibular membrane endolymph) – Cochlear duct (scala media) Stria vascularis • Basilar membrane supporting Organ of Corti – Organ of hearing Spiral organ – Tympanic canal (scala tympani) (of Corti) Scala tympani Basilar (contains membrane perilymph) (b) Figure 15.28b 3 1/24/2016 Organ of Corti Tectorial membrane Inner hair cell Organ of Corti Hairs (stereocilia) Afferent nerve fibers Outer hair cells Supporting cells Fibers of cochlear nerve Basilar membrane (c) Figure 15.28c Physiology of hearing Physiology of Hearing in a Nutshell • Transduction of sound Sounds set up vibrations in air that beat against the eardrum that pushes a chain of tiny bones Mechanical energy in middle ear that press fluid in the internal ear against membranes that set up shearing forces that pull on the tiny hair cells that stimulate nearby Fluid pressure wave in inner ear neurons that give rise to the impulses that travel to the brain – and you hear. Nerve impulse (This is from your textbook) Area of High frequency (short wavelength) = high pitch high pressure Low frequency (long wavelength) = low pitch (compressed molecules) Area of Wavelength low pressure (rarefaction) Crest Pressure Trough Time (s) Air pressure Air (a) Frequency is perceived as pitch. Distance Amplitude High amplitude = loud A struck tuning fork alternately compresses Low amplitude = soft and rarefies the air molecules around it, creating alternate zones of high and low pressure. Pressure (b) Sound waves radiate outward in all directions. Time (s) (b) Amplitude (size or intensity) is perceived as loudness. Figure 15.29 Figure 15.30 4 1/24/2016 Malleus Incus Stapes vibrating Helicotrema Cochlea Auditory ossicles in oval window Malleus Incus Stapes Cochlear nerve Sound waves Perilymph Scala vestibuli Oval Helicotrema window Scala tympani 3 8 Scala 7 tympani Cochlear duct 4 2 Scala 3 5 Basilar vestibuli membrane 6 Basilar 1 2 9 membrane 1 External auditory 8 canal Spiral organ (organ of Corti) Tectorial membrane Vestibular membrane Sounds with frequencies below hearing travel through Cochlear duct the helicotrema and do not Tympanic (contains endolymph) Tympanic Round excite hair cells. membrane window membrane Sounds in the hearing range (a) Route of sound waves through the ear Secondary tympanic go through the cochlear duct, membrane vibrating 1 Sound waves vibrate 3 Pressure waves created by vibrating the basilar membrane Middle ear Auditory tube in round window the tympanic membrane. the stapes pushing on the oval and deflecting hairs on inner 2 Auditory ossicles vibrate. window move through fluid in hair cells. Pressure is amplified. the scala vestibuli. Figure 15.31a Tectorial membrane Inner hair cell Basilar membrane Hairs (stereocilia) Afferent nerve fibers Outer hair cells High-frequency sounds displace the basilar membrane near the base. Supporting cells Fibers of basilar membrane Fibers of Medium-frequency sounds displace the basilar membrane near the middle. cochlear Base Apex (short, (long, nerve stiff floppy fibers) fibers) Low-frequency sounds displace the basilar membrane near the apex. Frequency (Hz) (b) Different sound frequencies cross the basilar membrane at different locations. Basilar membrane (c) Figure 15.31b Figure 15.28c • Movement of the basilar membrane bends the hair cells Medial geniculate nucleus of thalamus Primary auditory cortex in temporal lobe Inferior colliculus Lateral lemniscus Superior olivary nucleus Midbrain (pons-medulla junction) Cochlear nuclei Medulla Vibrations Vestibulocochlear nerve Vibrations Spiral ganglion of cochlear nerve Bipolar cell Spiral organ (of Corti) Figure 15.33 5 1/24/2016 Localization of Sound Abnormalities of hearing • Conductive deafness • Timing comparison –Interference in movement of middle ear bones – Side nearest sound detects sound first • Impacted earwax, perforated eardrum or otosclerosis of the ossicles (overgrowth • Comparison of volume of bone) – High pitched = blocked by head • Sensorineural deafness – • Perceived as loudest in ear nearest the source Damage to the neural structures • Aging, prolonged exposure to loud sounds – Low pitched = curve around head • Perceived as equally loud in both ears Abnormalities of hearing Abnormalities of hearing • Otitis media • Otosclerosis Abnormalities of hearing Abnormalities of hearing • Meniere’s Disease • Tinnitus – Episodes of vertigo – Ringing, clicking, hissing, or roaring – Progressive hearing loss – Sometimes can be heard with a stethoscope (o bjective tinnitus) – – Tinnitus May occur in the same rhythm as the heartbeat – – Caused by noise-induced hearing loss, ear infections, diseases of blood Feeling of fullness or vessels, head injury, neurological problems, brain tumors, earwax… pressure in ear – Usually only in one ear 6 1/24/2016 Vestibular Apparatus Physiology of Equilibrium Otoliths Kinocilium Otolithic Stereocilia membrane • Information about position and movement of head Hair bundle – Vestibular apparatus Macula of • Utricle utricle • Saccule Vesibule Macula of saccule • Semi-circular canals Hair cells Maculae are Supporting perpendicular cells to one another Vestibular nerve fibers Figure 15.34 Vestibule Semi-Circular canals • Macula = receptor – Crista ampullaris –Utricle • Sensory receptor for dynamic equilibrium – One in the ampulla of each semicircular canals • Horizontal movements – Major stimuli are rotatory movements • Tilting the head side to side –Saccule • Vertical movements Cupula Crista Equilibrium ampullaris Endolymph • Hair bundle (kinocilium Motion Sickness plus stereocilia) – Conflicts between eye movements and equilibrium Hair cell • Nystagmus Membranous Crista • Physiologic labyrinth ampullaris Supporting Fibers of vestibular nerve cell – Involuntary eye movement, part of a reflex (a) Anatomy of a crista ampullaris in a – Preserves clear vision during rotation of the head semicircular canal • Pathologic Cupula – Abnormal eye movement – eyes move as though the head is rotating while the head is still – Caused by damage to any part of the vestibular system (b) Scanning electron micrograph of a crista ampullaris (200x) Figure 15.36a–b 7.
Load more

Recommended publications
  • Sound and the Ear Chapter 2
    © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Chapter© Jones & Bartlett 2 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Sound and the Ear © Jones Karen &J. Kushla,Bartlett ScD, Learning, CCC-A, FAAA LLC © Jones & Bartlett Learning, LLC Lecturer NOT School FOR of SALE Communication OR DISTRIBUTION Disorders and Deafness NOT FOR SALE OR DISTRIBUTION Kean University © Jones & Bartlett Key Learning, Terms LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR Acceleration DISTRIBUTION Incus NOT FOR SALE OR Saccule DISTRIBUTION Acoustics Inertia Scala media Auditory labyrinth Inner hair cells Scala tympani Basilar membrane Linear scale Scala vestibuli Bel Logarithmic scale Semicircular canals Boyle’s law Malleus Sensorineural hearing loss Broca’s area © Jones & Bartlett Mass Learning, LLC Simple harmonic© Jones motion (SHM) & Bartlett Learning, LLC Brownian motion Membranous labyrinth Sound Cochlea NOT FOR SALE OR Mixed DISTRIBUTION hearing loss Stapedius muscleNOT FOR SALE OR DISTRIBUTION Compression Organ of Corti Stapes Condensation Osseous labyrinth Tectorial membrane Conductive hearing loss Ossicular chain Tensor tympani muscle Decibel (dB) Ossicles Tonotopic organization © Jones Decibel & hearing Bartlett level (dB Learning, HL) LLC Outer ear © Jones Transducer & Bartlett Learning, LLC Decibel sensation level (dB SL) Outer hair cells Traveling wave theory NOT Decibel FOR sound SALE pressure OR level DISTRIBUTION
    [Show full text]
  • The Standing Acoustic Wave Principle Within the Frequency Analysis Of
    inee Eng ring al & ic d M e e d Misun, J Biomed Eng Med Devic 2016, 1:3 m i o c i a B l D f o e v DOI: 10.4172/2475-7586.1000116 l i a c n e r s u o Journal of Biomedical Engineering and Medical Devices J ISSN: 2475-7586 Review Article Open Access The Standing Acoustic Wave Principle within the Frequency Analysis of Acoustic Signals in the Cochlea Vojtech Misun* Department of Solid Mechanics, Mechatronics and Biomechanics, Brno University of Technology, Brno, Czech Republic Abstract The organ of hearing is responsible for the correct frequency analysis of auditory perceptions coming from the outer environment. The article deals with the principles of the analysis of auditory perceptions in the cochlea only, i.e., from the overall signal leaving the oval window to its decomposition realized by the basilar membrane. The paper presents two different methods with the function of the cochlea considered as a frequency analyzer of perceived acoustic signals. First, there is an analysis of the principle that cochlear function involves acoustic waves travelling along the basilar membrane; this concept is one that prevails in the contemporary specialist literature. Then, a new principle with the working name “the principle of standing acoustic waves in the common cavity of the scala vestibuli and scala tympani” is presented and defined in depth. According to this principle, individual structural modes of the basilar membrane are excited by continuous standing waves of acoustic pressure in the scale tympani. Keywords: Cochlea function; Acoustic signals; Frequency analysis; The following is a description of the theories in question: Travelling wave principle; Standing wave principle 1.
    [Show full text]
  • Congenital Malformations of the External and Middle Ear: High-Resolution CT Findings of Surgical Import
    71 Congenital Malformations of the External and Middle Ear: High-Resolution CT Findings of Surgical Import Joel D. Swartz1 The external auditory canal, middle ear, and bulk of the ossicular chain develop from Eric N. Faerber1 the first branchial groove, first and second branchial arches, and first pharyngeal pouch. Embryologic development of these structures is complex and only rarely are two anomalies identical. Development of the inner ear structures occurs independently of external ear structures, and concomitant involvement is unusual. This study includes 11 cases of unilateral external auditory canal atresia and two cases of bilateral atresia. Eight cases (four bilateral) of isolated congenital ossicular anomalies are also included. Emphasis is placed on findings of surgical import. All patients were studied with computed tomography only, because it was believed that the bony and soft-tissue detail achieved is superior to that with conventional multidirectional tomography. High-resolution computed tomography (CT) has emerged as the method of choice for evaluation of the temporal bone. The purpose of this study was to provide a detailed analysis of congenital aural malformations to emphasize findings deemed critical by surgeons. Materials and Methods A General Electric 8800 CT/T scanner was used in all cases. Overlapping CT sections of 1.5 mm thickness were obtained in axial and coronal projections [1]. Infants and very young children required heavy sedation or general anesthesia. If an endotracheal tube was used, a coronal view in the supine position was necessary to facilitate patient monitoring. Excellent images were obtained in all patients, usually within 40 min . All images were targeted using high-bone-detail algorithms.
    [Show full text]
  • The Posterior Muscles of the Auricle: Anatomy and Surgical Applications
    Central Annals of Otolaryngology and Rhinology Research Article *Corresponding author Christian Vacher, Department of Maxillofacial Surgery & Anatomy, University of Paris-Diderot, APHP, 100, The Posterior Muscles of the Boulevard Général Leclerc, 92110 Clichy, France, Tel: 0033140875671; Email: Submitted: 19 December 2014 Auricle: Anatomy and Surgical Accepted: 16 January 2015 Published: 19 January 2015 Applications Copyright © 2015 Vacher et al. Rivka Bendrihem1, Christian Vacher2* and Jacques Patrick Barbet3 OPEN ACCESS 1 Department of Dentistry, University of Paris-Descartes, France Keywords 2 Department of Maxillofacial Surgery & Anatomy, University of Paris-Diderot, France • Auricle 3 Department of Pathology and Cytology, University of Paris-Descartes, France • Anatomy • Prominent ears Abstract • Muscle Objective: Prominent ears are generally considered as primary cartilage deformities, but some authors consider that posterior auricular muscles malposition could play a role in the genesis of this malformation. Study design: Auricle dissections of 30 cadavers and histologic sections of 2 fetuses’ ears. Methods: Posterior area of the auricle has been dissected in 24 cadavers preserved with zinc chlorure and 6 fresh cadavers in order to describe the posterior muscles and fascias of the auricle. Posterior auricle muscles from 5 fresh adult cadavers have been performed and two fetal auricles (12 and 22 weeks of amenorhea) have been semi-serially sectioned in horizontal plans. Five µm-thick sections were processed for routine histology (H&E) or for immuno histochemistry using antibodies specific for the slow-twitch and fast-twich myosin heavy chains in order to determine which was the nature of these muscles. Results: The posterior auricular and the transversus auriculae muscles looked in most cases like skeletal muscles and they were made of 75% of slow muscular fibres.
    [Show full text]
  • Anatomical Changes and Audiological Profile in Branchio-Oto-Renal
    THIEME 68 Review Article Anatomical Changes and Audiological Profile in Branchio-oto-renal Syndrome: A Literature Review Tâmara Andrade Lindau1 Ana Cláudia Vieira Cardoso1 Natalia Freitas Rossi1 Célia Maria Giacheti1 1 Department of Speech Pathology, Universidade Estadual Paulista - Address for correspondence Célia Maria Giacheti, PhD, Department of UNESP, Marília, São Paulo, Brazil Speech Pathology, Universidade Estadual Paulista UNESP, Av. Hygino Muzzi Filho, 737, Marília, São Paulo 14525-900, Brazil Int Arch Otorhinolaryngol 2014;18:68–76. (e-mail: [email protected]). Abstract Introduction Branchio-oto-renal (BOR) syndrome is an autosomal-dominant genetic condition with high penetrance and variable expressivity, with an estimated prevalence of 1 in 40,000. Approximately 40% of the patients with the syndrome have mutations in the gene EYA1, located at chromosomal region 8q13.3, and 5% have mutations in the gene SIX5 in chromosome region 19q13. The phenotype of this syndrome is character- ized by preauricular fistulas; structural malformations of the external, middle, and inner ears; branchial fistulas; renal disorders; cleft palate; and variable type and degree of hearing loss. Aim Hearing loss is part of BOR syndrome phenotype. The aim of this study was to present a literature review on the anatomical aspects and audiological profile of BOR syndrome. Keywords Data Synthesis Thirty-four studies were selected for analysis. Some aspects when ► branchio-oto-renal specifying the phenotype of BOR syndrome are controversial, especially those issues syndrome related to the audiological profile in which there was variability on auditory standard, ► BOR syndrome hearing loss progression, and type and degree of the hearing loss.
    [Show full text]
  • Low-Frequency Noise: a Biophysical Phenomenon M
    PSC REF#:288480 Public Service Commission of Wisconsin RECEIVED: 07/08/16, 8:46:12 AM Congres Geluid, Trillingen, Luchtkwaliteit en Gebied & Gebouw 2012 Low-frequency noise: a biophysical phenomenon M. Oud (medical physicist / consultant)* * [email protected], http://nl.linkedin.com/in/mireilleoud, the Netherlands Abstract Complaints on low-frequency noise were till recently fairly unexplained, but audiological research shed light on the mechanisms that enable perception of frequencies below the threshold of average normal hearing. It was shown that exposure to low-frequency sound may alter the inner ear. This results in an increase of sensitivity to low-frequency sounds, and as a result, previously imperceptible sounds becomes audible to the exposed person. Interactions between inner-ear responses to low and higher frequencies furthermore account for perception of low-frequency sound, as well as the property of the hearing system to perceive so-called difference tones. Introduction A growing minority of people experiences an increased sensitivity for low-frequency sound. Not surprisingly, they complain about noise, even about loud noise in some cases. Their complaints about the presence of hum, buzz, and rumble are often not recognized as a nuisance, since the majority of people does not perceive the very low frequencies. Low-frequency noise (LFN) may have serious health effects like vertigo, disturbed sleep, stress, hypertension, and heart rhythm disorders [1]. The number of sufferers is growing, and this has two possible causes. The sources of low- frequency sounds increased in volume and dimension over the past decades, and auditory sensitisation takes years to develop. Nowadays, the main source of low-frequency noise is the public infrastructure: wind turbines, gas transmission grid, industrial plants, road and railway traffic, sewerage, and so on.
    [Show full text]
  • Ear, Page 1 Lecture Outline
    Ear - Hearing perspective Dr. Darren Hoffmann Lecture Objectives: After this lecture, you should be able to: -Describe the surface anatomy of the external ear in anatomical language -Recognize key anatomy in an otoscopic view of the tympanic membrane -Describe the anatomy and function of the ossicles and their associated muscles -Relate the anatomical structures of the middle ear to the anterior, posterior, lateral or medial walls -Explain the anatomy of middle ear infection and which regions have potential to spread to ear -Describe the anatomical structures of the inner ear -Discriminate between endolymph and perilymph in terms of their origin, composition and reabsorption mechanisms -Identify the structures of the Cochlea and Vestibular system histologically -Explain how hair cells function to transform fluid movement into electrical activity -Discriminate the location of cochlear activation for different frequencies of sound -Relate the hair cells of the cochlea to the hair cells of the vestibular system -Contrast the vestibular structures of macula and crista terminalis Let’s look at the following regions: Hoffmann – Ear, Page 1 Lecture Outline: C1. External Ear Function: Amplification of Sound waves Parts Auricle Visible part of external ear (pinna) Helix – large outer rim Tragus – tab anterior to external auditory meatus External auditory meatus Auditory Canal/External Auditory Meatus Leads from Auricle to Tympanic membrane Starts cartilaginous, becomes bony as it enters petrous part of temporal bone Earwax (Cerumen) Complex mixture
    [Show full text]
  • Mathematical Model of the Cupula-Endolymph System with Morphological Parameters for the Axolotl (Ambystoma Tigrinum) Semicircular Canals
    138 The Open Medical Informatics Journal, 2008, 2, 138-148 Open Access Mathematical Model of the Cupula-Endolymph System with Morphological Parameters for the Axolotl (Ambystoma tigrinum) Semicircular Canals Rosario Vega1, Vladimir V. Alexandrov2,3, Tamara B. Alexandrova1,3 and Enrique Soto*,1 1Instituto de Fisiología, Universidad Autónoma de Puebla, 2Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Puebla, 3 Lomonosov Moscow State University, Mexico Abstract: By combining mathematical methods with the morphological analysis of the semicircular canals of the axolotl (Ambystoma tigrinum), a system of differential equations describing the mechanical coupling in the semicircular canals was obtained. The coefficients of this system have an explicit physiological meaning that allows for the introduction of morphological and dynamical parameters directly into the differential equations. The cupula of the semicircular canals was modeled both as a piston and as a membrane (diaphragm like), and the duct canals as toroids with two main regions: i) the semicircular canal duct and, ii) a larger diameter region corresponding to the ampulla and the utricle. The endolymph motion was described by the Navier-Stokes equations. The analysis of the model demonstrated that cupular behavior dynamics under periodic stimulation is equivalent in both the piston and the membrane cupular models, thus a general model in which the detailed cupular structure is not relevant was derived. Keywords: Inner ear, vestibular, hair cell, transduction, sensory coding, physiology. 1. INTRODUCTION linear acceleration detectors, and the SCs as angular accel- eration detectors, notwithstanding that both sensory organs The processing of sensory information in the semicircular are based on a very similar sensory cell type.
    [Show full text]
  • Measuring Cochlear Duct Length – a Historical Analysis of Methods and Results Robert W
    Koch et al. Journal of Otolaryngology - Head and Neck Surgery (2017) 46:19 DOI 10.1186/s40463-017-0194-2 REVIEW Open Access Measuring Cochlear Duct Length – a historical analysis of methods and results Robert W. Koch1*, Hanif M. Ladak1,2,3,4†, Mai Elfarnawany2† and Sumit K. Agrawal1,2,4,5† Abstract Background: Cochlear Duct Length (CDL) has been an important measure for the development and advancement of cochlear implants. Emerging literature has shown CDL can be used in preoperative settings to select the proper sized electrode and develop customized frequency maps. In order to improve post-operative outcomes, and develop new electrode technologies, methods of measuring CDL must be validated to allow usage in the clinic. Purpose: The purpose of this review is to assess the various techniques used to calculate CDL and provide the reader with enough information to make an informed decision on how to conduct future studies measuring the CDL. Results: The methods to measure CDL, the modality used to capture images, and the location of the measurement have all changed as technology evolved. With recent popularity and advancement in computed tomography (CT) imaging in place of histologic sections, measurements of CDL have been focused at the lateral wall (LW) instead of the organ of Corti (OC), due to the inability of CT to view intracochlear structures. After analyzing results from methods such as directly measuring CDL from histology, indirectly reconstructing the shape of the cochlea, and determining CDL based on spiral coefficients, it was determined the three dimensional (3D) reconstruction method is the most reliable method to measure CDL.
    [Show full text]
  • ANATOMY of EAR Basic Ear Anatomy
    ANATOMY OF EAR Basic Ear Anatomy • Expected outcomes • To understand the hearing mechanism • To be able to identify the structures of the ear Development of Ear 1. Pinna develops from 1st & 2nd Branchial arch (Hillocks of His). Starts at 6 Weeks & is complete by 20 weeks. 2. E.A.M. develops from dorsal end of 1st branchial arch starting at 6-8 weeks and is complete by 28 weeks. 3. Middle Ear development —Malleus & Incus develop between 6-8 weeks from 1st & 2nd branchial arch. Branchial arches & Development of Ear Dev. contd---- • T.M at 28 weeks from all 3 germinal layers . • Foot plate of stapes develops from otic capsule b/w 6- 8 weeks. • Inner ear develops from otic capsule starting at 5 weeks & is complete by 25 weeks. • Development of external/middle/inner ear is independent of each other. Development of ear External Ear • It consists of - Pinna and External auditory meatus. Pinna • It is made up of fibro elastic cartilage covered by skin and connected to the surrounding parts by ligaments and muscles. • Various landmarks on the pinna are helix, antihelix, lobule, tragus, concha, scaphoid fossa and triangular fossa • Pinna has two surfaces i.e. medial or cranial surface and a lateral surface . • Cymba concha lies between crus helix and crus antihelix. It is an important landmark for mastoid antrum. Anatomy of external ear • Landmarks of pinna Anatomy of external ear • Bat-Ear is the most common congenital anomaly of pinna in which antihelix has not developed and excessive conchal cartilage is present. • Corrections of Pinna defects are done at 6 years of age.
    [Show full text]
  • Special Ear Problem (Worksheet)
    Special Ear Problem (Worksheet) anvil hammer oval window Extenal auditory canal Cochlea Ear drum stirrip organ of corti Round window Basilar membrane A) Label on the drawing above: 1. External auditory canal 2. ear drum (tympanic membrane) 3. hammer (maleus) 4. anvil (incus) 5. stirrup (stapes) 6. cochlea 7. oval window 8. round window 9. basilar membrane 10. organ of Corti B) In one or two sentences, what is the function of the outer ear The outer ear collects sound and guides it to the eardrum. C) The external auditory canal functions like a 2.5 cm closed pipe. What are the first two resonances of this pipe and how do these explain features of Figure 12-7 on page 354 of your book (Giancoli)? The first two resonances are about 3500 Hz --- the frequency where your ear is most sensitive --- and 10,5000 --- which corresponds to kinks in the curves of Fig. 12-7. D)What is the boundary between the outer ear and the middle ear? The Eardrum E) In one or two sentences, what is the function of the middle ear? The middle ear takes the pressure wave coming from the (large area) eardrum and “amplifies” the pressure by about 40 to generate a wave in the fluid of the cochlea through the (small area) oval window. F) What is the boundary between the middle ear and the inner ear? The oval window. G) In one or two sentences, what is the function of the inner ear? The inner ear generates electrical signals from the (liquid) pressure waves generated at the oval window.
    [Show full text]
  • Deformation of Avian Middle Ear Structures Under Static Pressure Loads, and Potential Regulation Mechanisms ⁎ Raf Claesa,B, , Pieter G.G
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Ghent University Academic Bibliography Zoology xxx (xxxx) xxx–xxx Contents lists available at ScienceDirect Zoology journal homepage: www.elsevier.com/locate/zool Deformation of avian middle ear structures under static pressure loads, and potential regulation mechanisms ⁎ Raf Claesa,b, , Pieter G.G. Muyshondtc, Joris J.J. Dirckxc, Peter Aertsa,d a University of Antwerp, Laboratory of Functional Morphology, Universiteitsplein 1, B-2610 Antwerp, Belgium b Vrije Universiteit Brussel, Department of Mechanical Engineering, Pleinlaan 2, B-1050 Brussels, Belgium c University of Antwerp, Laboratory of BioMedical Physics, Groenenborgerlaan 171, B-2020 Antwerp, Belgium d University of Ghent, Department of Movement and Sport Science, Watersportlaan 2, B-9000 Ghent, Belgium ARTICLE INFO ABSTRACT Keywords: Static pressure changes can alter the configuration and mechanical behavior of the chain of ossicles, which may Pharyngotympanic tube affect the acoustic transfer function. In mammals, the Eustachian tube plays an important role in restoring Ambient pressure ambient middle ear pressure, hence restoring the acoustic transfer function and excluding barotrauma of the Middle ear middle and inner ear. Ambient pressure fluctuations can be potentially extreme in birds and due to the simple Chicken structure of the avian middle ear (one ossicle, one muscle), regulation of the middle ear pressure via reflexive Mallard opening of the pharyngotympanic tube appears all the
    [Show full text]