CDO 335 Week Fourteen Notes
CDO 335 Week Fourteen Notes CDO 335
Popular in Anatomy & Physiology of Speech and Hearing
verified elite notetaker
Popular in Communication Disorders & Sciences
This 6 page Class Notes was uploaded by Rachel Roede on Friday December 4, 2015. The Class Notes belongs to CDO 335 at Central Michigan University taught by Lori Bissell in Summer 2015. Since its upload, it has received 16 views. For similar materials see Anatomy & Physiology of Speech and Hearing in Communication Disorders & Sciences at Central Michigan University.
Reviews for CDO 335 Week Fourteen Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 12/04/15
CDO 3354 Week Fourteen Notes Audition Eat as Energy Transducer Acoustical Energy o Air molecule compression waves o How it reaches outer ear Mechanical Energy o Tissues vibration o Going across membranes, or across and/or through a solid structure Hydraulic Energy o Liquid compression waves o How it travels through a liquid Mechanical Energy o Switches back to this Electrical Energy o Nervous transmissions o Final form which neurons can understand Principle Parts of the Ear External or Outer Ear o Pinna/Auricle o External Auditory Meatus (EAM) (Ear Canal) Composed of cartilage and bone Middle Ear o Tympanic Cavity o Tympanic Membrane (TM) (Ear Drum) o 3 Tiny Bones (Ossicles) o Eustachian Tube Leads from middle ear cavity to nasopharynx (superior portion of throat) Opens and closes to equalize pressure Inner Ear o Cochlea (sound reception organ) o Vestibule (entrance) (balance) o Semi-circular Canals (balance) o VIII Cranial Nerve (Vestibulocochlear/auditory cranial nerve) Sent to temporal lobe The Outer Ear Principle Parts of the Auricle (Pinna) o Helix Curved portion at top of ear o Tragus Cartilage that covers ear canal Oriented forward o To direct sound into ear canal Attaches to temporal bone lateral to the petrous portion Made up of cartilage Loss results in -3 to -5 dB of loudness (not extreme at all) External Auditory Meatus (EAM) Part of outer ear 2-3 cm long Curved, irregular canal Made up of cartilage and bone segments From the tympanic membrane, it angles down for drainage in an adult Secretes cerumen (wax) and grows hair o For protection 12-2-15 Tympanic Membrane (TM) Medial boundary of the outer ear Lateral boundary of the middle ear Sits at 45 degree angle to the EAM floor Cone shaped Extremely thin, pliable, tough Composed of 3 layers: o Outer Facing EAM Continuous with the cutaneous (skin) tissue of the EAM o Inner Continuous with the mucous lining of the middle ear o Middle 2 sets of fibers Radiating Circular Fibers are deficient at the Notch of Rivinus AKA Flaccid section (parts flaccida) Behind this s the manubrium of the malleus Center is the Umbo Middle Ear Ossicles Malleus (hammer) Incus (anvil) Stapes (stirrup) Smallest bones in the body Their auditory chain transmits the sound energy to the inner ear, and in so doing: o Amplifies low intensity sounds o Attenuates (lessens) high intensity sounds somewhat These help to make all sounds the right volume for protection Malleus Largest bone Manubrium attaches to the tympanic membrane at the umbo and along the length of the manubrium Head of the malleus articulates with the body of the incus (second ossicle) Incus Body of the incus articulates with the head of the malleus Two processes o Short process (don’t need to know for quiz/exam) o Long Process articulates with the head of the stapes Stapes Head of the stapes articulates with the long process of the incus Has two crura which connect to an oblong footplate Footplate articulates with the vestibule at the oval window (entrance to inner ear) Muscles of the Middle Ear Tensor Tympani o **Only need to know Innervation and Function** o Origin Temporal bone canal on the anterior wall o Insertion Upper manubrium of the malleus o Innervation V Trigeminal Nerve o Function Draws malleus medially and anteriorly to reduce movement of the ossicular chain and the tympanic membrane Stapedius o **Only need to know Innervation and Function** o Origin Temporal bone canal on the posterior wall o Insertion Head of stapes o Innervation VII Facial Nerve o Function Draws stapes posteriorly to reduce movement of the ossicular chain and reduce compression of the oval window Acoustic Reflex Created by both middle ear muscles working together Evoked at 80-90 dB above threshold o Normal is approx. 60 dB Even expectation of sound can trigger it Latent response o Ineffective in explosive noise or not expected noise Fatigues over time o Ineffective in long exposures of sound Middle Ear Landmarks and Topographical Anatomy (pg. 459) 6 walled irregularly shaped chamber ***Know what is on the other side of each wall** o Superior wall Roof separates middle ear cavity from: The brain o Inferior Wall Floor separates middle ear cavity from: Jugular vein in neck o Lateral Wall (Tympanic Membrane) Membranous, separates MEC from: External auditory meatus o Medial Wall Labyrinthine which separates MEC from: Vestibule and cochlea o Anterior Wall Coratid which separates MEC from: Coratid Artery and Eustachian tube o Posterior Wall Mastoid separates MEC from: Mastoid air cells in temporal lobe The Inner Ear End organ for hearing (cochlear) End organ for balance (vestibular) Labyrinth o Bony (temporal bone) o Membranous Bony Labyrinth (3 parts) Vestibule o Area of communication between the sensation of areas of balance and hearing (semicircular canals and cochlea) o Communicates with the middle ear at the oval window (filled with the footplate of the stapes on the medial wall of the middle ear Bony Semicircular Canals (pg. 463) Situated at nearly right angles to each other o Posterior o Superior o Lateral/external/horizontal Slight dilation where each joins at the vestibule is called the ampulla Used for balance Filled with fluid Bony Cochlea Center core modiolus Projecting spiral shelf spiral lamina Completes 2 ¾ spiral turns Ends at the apex helicotrema Openings o At the vestibule (oval window) o At the round window (sound back out to middle ear) Fluid Filled Inside cochlea Perilymph Fluid (extra fine filtrate of blood) o Thin, watery in composition o Originates from the membrane lining in the bony labyrinth o Similar to cerebrospinal fluid form he covering of the brain o Fills 2 of the 3 chambers of the cochlea Membranous Cochlea Follows the same shape as the bony cochlea Formed by 2 membranes which arise from the spinal lamina and inserts in the outer wall of the bony cochlea o Reissner’s Membrane (roof of middle section) o Basilar Membrane Inserts at the spiral ligament Scala Media (cochlear duct) is middle section/chamber o Filled with Endolymph Fluid o Divides the bony cochlea into 2 other chambers Scala Vestibule o Communicates with the vestibule Scale Tympani o Communicates with the tympanic cavity (middle ear cavity) o Round window is attached here These communicate with each other at the helicotrema Scala Media Upper wall is Reissner’s Membrane Lower wall is Basilar Membrane o Supports the Organ of Corti which lies within the scala media Tectorial Membrane arises near the edge of the spiral lamina and extends over the Organ of Corti Organ of Corti Two pillars (rods) of Corti Inner hair cells Outer hair cells Tunnel of Corti between them – filled with Cortilymph