Special Senses -Hearing and Balance PDF

Special Senses: Hearing and Balance Course Learning Objective Special Senses: Identify micro- and macroscopic structures involved in the special senses using virtual microscopy, 2-D, and 3-D images to link these processes to the larger nervous system...

Special Senses: Hearing and Balance Course Learning Objective Special Senses: Identify micro- and macroscopic structures involved in the special senses using virtual microscopy, 2-D, and 3-D images to link these processes to the larger nervous system. Lecture Learning Objectives 1. Recall the three regions of the ear 6. List the components of the bony and their primary functions and membranous labyrinths of the 2. List the components of the external inner ear and explain their ear differences (e.x., structure, fluid) 3. List the components of the middle 7. Describe sound transmission ear, including their functions including the steps, structures involved, and the roll of sound 4. Explain the anatomical reason frequency juveniles are more prone to middle ear pathologies 8. Recall the auditory pathways 5. Visually identify the components of 9. Explain the roll of inner ear the external, middle, and inner ear structure structures and the (*) (images and histology) pathways involved in equilibrium and balance  LO1 Special Senses: Hearing and Balance External ear EAM Transfer of sound cochlea Bound internally by tympanic membrane ossicles Middle ear Transfer of sound 0 Open to nasopharynx via pharyngotympanic tube Contains the bones of the ear TM CYL Internal ear Transfer of sound to CNS Movement of fluid in internal ear results in the sensations of hearing and equilibrium (balance) Gray’s Basic Anatomy, Drake et al., (2018) SoundwavestravelthruExternalEar via EAM  perilymph Inner Ear Fluids Fatih MembrandusLabyrinth BonyLabyrinth Rigidouterbonywall communicating membranoussacs ofTemporalb onepetrouspart ducts winBonycavities cochleavestibule setmicircular anterior imidates coffinsn EhsepmicismiarYogyts Balance opening utricle saccture bilated say membranous ve AMPU'S ScalaTympani yay Sestibuli media crinthian's terminates vestibular 151Icorti chpurat shifts hello crattignal Perilymph Helicotrema btwsvest apex airman Dunghill Deceleration ofHead https://www.youtube.com/watch?v=bhshQKElY_I  LO2 External Ear Auricle (pinna) External acoustic meatus Outside-ear-hole Contains ceruminous (produce cerumen/earwax) and sebaceous glands protection Tympanic membrane (ear drum) Oriented like a mini radar or satellite dish to receive sound waves vibration Formed by elastic cartilage and temporal bone Gray’s Basic Anatomy, Drake et al., (2018)  LO3 Middle Ear Tympanic cavity- space formed by the inner ear Lined with a continuous mucous membrane Openings Mastoid air cells like sinuses Pharyngotympanic tube (Eustachian tube/ auditory tube) Opening into the posterior aspect of nasal cavity Function: equalize pressure in the middle ear yawnof Opened by contraction muscles in the soft palate Why is it important to know the openings? Coronal section of confection temporal bone Gray’s Basic Anatomy, Drake et al., (2018)  pe LO4 Middle Ear- Pathologies Otitis media- middle ear infection Adult Netter’s Image Bank aminage Juvenile horiz Clinically Oriented Anatomy, Moore et al., (2018) peartbeatain healthy TM Mastioditis Fatid mastoidair cells infy abn bonegrowth  LO3 Middle Ear- Contents Auditory ossicles Malleus (hammer) Moves with tympanic membrane Incus (anvil) Stapes (stirrup) I Oval window so intro Base of stapes in smaller than tympanic membrane= 10x increase in vibratory force amplified External tympanic membrane Gray’s Basic Anatomy, Drake et al., (2018)  LO3 Middle Ear- Contents tribration sound View from inside middle ear Stapedius muscle (prevents Anterior Posterior excessive movement of stapes) Tensor tympani muscles (reduces amplitude to prevent damage) Chorda tympani nerve (CN VII branch) Tympanic plexus of nerves (from CN IX) sensation of ME Gray’s Basic Anatomy, Drake et al., (2018)  LO5 Gross Anatomical Structures 1. Pinna 2. External acoustic meatus 4 5 6 3. Tympanic membrane 4. Malleus 1 3 5. Incus 2 6. Stapes 7. Pharyngotympanic tube 7 Netter’s Image Bank  LO6 Inner Ear instant Netter’s Image Bank Contains vestibulocochlear organ Reception of sound and maintenance of balance Anterolateral view of bony labyrinth Protected by petrous part of temporal bone Bony labyrinth Fluid filled space (perilymph) Comprised of surrounding cranial bone (otic capsule) Posteromedial view Membranous labyrinth of membranous Filled with endolymph labyrinth Netter’s Image Bank Series of sacs and ducts suspended in bony labyrinth Gray’s Basic Anatomy, Drake et al., (2018)  LO6 Inner Ear Bony labyrinth Cochlea Vestibule opening Semicircular canal balance Membranous labyrinth Cochlear labyrinth Vestibular labyrinth Semicircular ducts inside Gray’s Basic Anatomy, Drake et al., (2018) Hearing and Auditory Pathways  LO6 Cochlea Anterior view Hearing Filled with perilymph Spiral containing three distinct parts that spirals around a bony core (modiolus) 0 A. Cochlear duct (cochlear labyrinth) B. Scala tympani andTM C. Scala vestibuli hone Modiolus carries cochlear nerve (branch Cross section of cochlea of CN VIII) and vessels Communicates with round window containing a secondary tympanic membrane Clinically Oriented Anatomy, Moore et al., (2018) Communicates with subarachnoid space of cranium via the cochlear aqueduct Gray’s Basic Anatomy, Drake et al., (2018)  LO6 Cochlear Labyrinth Cochlear labyrinth Comprised of the cochlear duct housed within the spiral canal of cochlea Filled with endolymph Location of spiral organ Gray’s Basic Anatomy, Drake et al., (2018)  LO6 Cochlear Duct Filled with endolymph sup Tube closed at one end on and triangular in cross conf section Apex is called inf helicotrema ofSV ST vibrations move  LO6 Cochlear Duct Contains the spiral organ (organ of Corti) Sits on basilar membrane sep Tectorial membrane brinasinvibrations Supporting cells Outer and inner hair cells Synapses with cochlear nerve  LO7 Sound Transmission Gray’s Basic Anatomy, Drake et al., (2018) 2 3 1 vibrate 4 moves 6 5 I sounds cochduct sounds brother further absorbedout  LO7 Sound Transmission Gray’s Basic Anatomy, Drake et al., (2018) 1. Vibrations enter middle ear from tympanic membrane 2 3 2. Vibrations transfer through ossicles 1 4 6 3. Vibrations are transferred into waves of hydraulic pressure in perilymph from 5 base of stapes into scala vestibuli 4. Pressure waves pass deform cochlear duct, where information is transferred to spiral organ on basilar membrane 5. Waves of hydraulic pressure descend back through scala tympani 6. Pressure waves become vibrations again, impacting secondary tympanic membrane in round window  LO7 Sound Transmission The spiral organ is stimulated by the Innervated by cochlear deformation of nerve (branch of CN VIII) cochlear duct by hydraulic pressure Cell bodies of primary waves of perilymph in sensory neurons are scala vestibuli located in the spiral ganglion High frequency sounds displace basilar membrane closer to the base of cochlea (shorter distance) rotdow Low frequency sounds displace basilar membrane closer to helicotrema (longer distance) Gray’s Basic Anatomy, Drake et al., (2018) If talk farther  LO8 Auditory Pathway 1. Hair cells in spiral organ 6. Inferior colliculisound vision 2. Spiral ganglion (primary neurons) or 3. Cochlear nerve 6. Superior olivary nuclei 4. CN VIII 0 5. Cochlear nuclei in brain stem (synapse- secondary neurons) (integration of 7. Thalamus (tertiary neurons) information occurs) 8. Primary auditory cortex in temporal lobe Clinically Oriented Anatomy, Moore et al., (2018) Equilibrium and Balance  LO6 Vestibule and Vestibular Labyrinth Equilibrium head in space Vestibule entryinto IE Oval chamber of bony labyrinth Contains the utricle and saccule of the vestibular labyrinth Vestibular labyrinth Utricle and saccule Maculae- specialized epithelium with hair cells that lines utricle and saccule Gray’s Basic Anatomy, Drake et al., (2018)  LO6 Semicircular Ducts and Canals Equilibrium Semicircular canals bony lab Three tubes oriented at right angles to one another to occupy three planes in space Bony ampulla- expansions at base of semicircular canals Semicircular ducts canals in Portion of membranous labyrinth within semicircular canals Ampulla- contain hair cells for sensation Open into utricle saccule Gray’s Basic Anatomy, Drake et al., (2018)  LO9 Equilibrium and Balance Innervation occurs via vestibular nerve (branch of CN VIII) Sense motion by recording movement of endolymph via hair cells Utricle and saccule Sensitive to gravity and linear acceleration or deceleration Maculae- specialized epithelium with hair cells Hair cells project into otolithic membrane- gelatinous layer with cellstorestnerve mineralized structures (otoliths) Tocksmove hair  LO9 Equilibrium and Balance Ampulla Contain crista ampullaris- ridge containing hair cells that project into cupula Sense rotational acceleration Moreas or decelerating of head due to movement of surrounding mules endolymph movement in semicircular ducts Fnterp.by cell hair vertigo Gray’s Basic Anatomy, Drake et al., (2018)  LO9 Vestibular Sensation Pathway 1. Hair cells in maculae of utricle and saccule, ampulla 2. Vestibular ganglion (primary neurons) 3. Vestibular nerve 4. CN VIII 5. Vestibular nuclei in medulla (synapse- secondary neurons) a. Project into vestibulospinal tract to maintain muscle tone and balance b. Project to motor nuclei in brainstem and spinal cord to adj.bod regetryinf p control reflexive motor activities associated with eye movements and head and neck function balana thalamus, cerebral 0taadj.mumt c. Cerebellum, cortex (tertiary neurons) Clinically Oriented Anatomy, Moore et al., (2018)  LO5 Gross Anatomical Structures 1. Scala vestibuli 2. Vestibular membrane 3. Cochlear duct 1 4. Spiral organ SV NCP3 2 5 5. Tectorial membrane 6 6. Hair cells gang 9 spiral 7. Basilar membrane St 8 8. Scala tympani code 10 7 4 9. Spiral ganglion 10. Cochlear nerve Netter’s Image Bank  LO5 Gross Anatomical 6 Structures 7 9 1. Cochlea 2. Vestibule 3. Utricle 1 4. Saccule 5. Ampulla 6. Bony ampulla 2 10 7. Semicircular canals 3 5 8 8. Semicircular duct 9. Oval window 10. Round window 11 11. Cochlear branch 12 12. Vestibular branch 4  LO5 Inner Ear Histology 1. Scala vestibuli 2. Vestibular membrane 1 4 3. Cochlear duct 2 (scala media) 3 4. Basilar membrane 6 5. Spiral organ 4 6. Scala tympani mirroredview too  LO5 Inner Ear Histology 1 1. Scala vestibuli 2 2. Vestibular membrane 6 3. Cochlear duct 3 4. Basilar membrane munt 5. Scala tympani a gel 6. Spiral organ 4 a. Tectorial membrane b. Hair cells b 5