14111252
Description
Flashcards by Caitlin French, updated more than 1 year ago
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Created by Caitlin French
almost 6 years ago
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| Question | Answer |
| 3 Regions of the Ear | 1. Outer Ear - hearing 2. Middle Ear - hearing 3. Inner Ear - hearing/equilibrium |
| Outer Ear Structure | Auricle (pinna) Helix - rim Lobule - earlobe EAM - from auricle to tymp. memb., secretes cerumen (ear wax) Tympanic Membrane - thin CT, vibrates, transf. sound energy to ossicles FUNCTION = protect and direct sound waves to middle ear |
| Middle Ear Structure | Tympanic Cavity - contains 3 ossicles, oval window, round window FUNCTION = sounds waves become mechanical forces Eustachian Tube - conects middle ear to nasopharynx FUNCTION = equalizes pressure on both sides of tymp. memb. |
| Ossicles | 1. Malleus (hammer) - attached to TM 2. Incus (anvil) 3. Stapes (stirrup) - base fits to oval window Ossicles suspended by ligaments/synovial joints Transmit vibratory motion from TM to oval window Muscles - tensor tympani and stapedius - dampen sound by tensing TM limiting mvmt of stapes in oval window |
| Inner Ear | 1. Vestibule 2. Cochlear 3. Semicircular Canals Filled with perilymph Continuous with CSF |
| Inner Ear - Vestibule | Cavity of bony labyrinth Saccule = extends to cochlear Utricle = extends to SCC House equilibrium receptor regions - Maculae (epth. tissue) respond to gravity and head position |
| Inner Ear - Semicircular Canals | 1. Anterior - vertical 2. Lateral - horizontal 3. Posterior - vertical Ducts line each canal and comm. with utricle Ampulla = swollen end of SCC Equilibrium receptors = Crista Ampullaris (respond to dynamic rot. of head) |
| Cochlear | Scala Vestibuli = perilymph, superior Scala Media = cochlear duct, endolymph Scala Tympani = perilymph, inferior Branch of vestibulocochlear nerve from organ of Corti to brain |
| Organ of Corti | Basilar memb. attached to Organ of Corti on 1 side of cochlear duct Hairlike stereocilia protrude from hair cells into endolymph, touching tect. memb. Tect. Memb + Cilia vibrate/bend, opening gated ion channels, initiating AP, releasing neurotransmitter, transmitted to brain via cochlear fibres..... SOUND IS PERCEIVED! |
| Mechanism of Heaing | Outer ear structures direction vibrations to middle ear along EAM, TM vibrates, pressure on ossicles amplifying sound, vibrations travel through oval window, into scala vestibuli, across cochlear duct (stim hairs in organ of Corti and stim nerve to send impulses to brain), along scala tympani and out round window |
| Auditory Pathway | Impulses pass cochlear → cochlear nuclei via spiral ganglion → medulla → superior olivary nucleus → inferior collliculus → thalamus → primary auditory cortex in temporal lobe |
| Deafness | CONDUCTION = blockage to inner ear (perforated TM, impacted earwax, etc.) SENSORINEURAL = damage to neural structures (cochlear hair cells → auditory cortical cells - no repair - loud sounds, explosions, infections, etc.) |
| Static Equilibrium - Maculae (Saccule & Utricle) | Respond to linear acceleration Otolithic memb = ears strongs over gelatinous material over hair cells Utricle (UTE) = maculae horizontal, hair cells vertical, respond to horizontal mvmt + side mvmt of head Saccule (SKYSCRAPER) = macula vertical but hair cells horizontal, respond to vertical mvmt. ***Hairs synapse with CN#8 vestibulocochlear nerve*** |
| Dynamic Equilibrium - Crista Ampullaris | Ampulla in each SCC, respond to rot. mvmt. Cupula = loose network of strands, radiate outwards to contact hair cells Dendrites of VC nerve fibres encircles base of hair cells |
| Balance & Orientation Pathways | Vestibular Receptors = saccule, utricel, SCC Somatic Receptors = proprio-receptors in joints/muscles CN#11 for neck mvmt CN#3, 4, & 6 for eye mvmt |
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