ANP 1106 Lecture Notes - Lecture 5: Ear Canal, Elastic Cartilage, Inner Ear
12 Jul 2018
School
Department
Course
Professor
Document Summary
Has opening for pharyngotumpanic (auditory) tube formerly eustachian tube: links middle ear- nasopharynx. Sometimes emergency myringotomy: eardrum lanced, tube inserted in eardrum to drain middle -, mastoiditis external ear, mastoid air cells infected, can spread to brain, difficult to rx but now antibiotics instead of surgery available. Filled with endolymph: divisions of cn viii that connect to membranous labyrinth structures. Components: supporting cells, hearing receptors: cochlear hair cells (inner/outer, stereocilia & kinocilium in overhanging tectorial membrane, movement -> sound wave transduction, cochlear nerve fibres -> cns. 1500-4000 hz: most sounds mixes of many pitches: sound quality, provides richness and complexity, amplitude. Intensity: wave crest height: loudness: subjective intensity, measure in db. Increased 10 db-> 10 x intensity / 2x loudness: barely audible: 0 db, conversation: 50 db, noisy room: 70 db, prolonged exposure >90 db -> severe hearing loss, pain threshold: 120 db. Auditory transduction: excitation of hair cells in spiral organ, when section of basilar membrane moves.
