The vestibulocochlear organ lao ming All rights reserved The vestibulocochlear (ear) Composition External ear Middle ear Internal ear The external ear 1) location each side of the head 2) Structure Elastic fibrocartilage covered with skin (Lack of fat) 3)shape: auricular lobule external acoustic pore the auricle External acoustic meatus tympanic membrane 1.the auricle 2. External acoustic meatus 1) Two parts Cartilagious part Bony part 2) Covered with skin closely 3) curve Lat.forwards upwards Med.forwards downwards *two parts: flaccid & tense part *cone of light (bright area) on anterioinferior to the umbo of tympanic membrane 3.The tympanic membrane the auricle should be drawn upwards backwards in adult. downwards backwards in children. * to observe cone of light thin, semitransparent act as the floor of meatus,45 obliquely concave outside superior wall (tegmental wall) inferior wall (jugular wall) anterior wall(carotid wall) posterior wall (mastoid wall ) lateral wall (membranous wall ) medial wall (labyrinth wall) (Key & difficult point) 1)The six walls The middle ear Tympanic cavity Auditory tube Mastoid air cells 1.Tympanic cavity 1). malleus incusstapes ( Tympanic ( fenestra Membrane ) vestibuli ) 2).Tensor tympanic Stapedius 2)The chain of auditory ossicles & muscles in tympanic cavity (inflammation of the pharynx causes otitis media easily in children) 2.Auditory tube *two parts: bony & cartliginous parts *two openings: pharyngeal & tympatic orifices * auditory tube in children is shorter, wider and more horizontal 3.The mastoid antrum & cells in the mastoid The internal ear (labyrinth)----( two parts) bony labyrinth bony Semicircular canals vestibule Cochlea Membranous labyrinth Cochlear duct Utricle saccule semicircular ducts 3 in number (anterior, posterior and lateral ~) 5 crura 3 ampulla 1. The bony semicircular canals vestibule 2. vestibule Fenestra ventibuliclosed by the stape Fenestra cochleae --- closed by second tympanic membrane three parts: Scala vestibuli cochlear duct scala tympani bony canals of cochlea winding for 2 1/2 around central modilus 3.The cochlea Semicircular ducts Cochlear duct utricle saccule The membranous labyrinth The Receptors inside membranous labyrinth 1.ampulary crest organ of kinetic balance 2.maccuae of saccule and utricles organ of static balance Cortis apparatus 3.spiral organ (Cortis apparatus) for auditory sensation Perilymph: between bony & membranous labyrinth Endolymph: within membranous labyrinth Perilymph & Endolymph The conduction of sound: air conduction The sound wave the external acoustic meatus tympanic membrane chain of the auditory ossicles fenestra vestibuli the perilymph within the scale vestibuli the endolymph within the cochlear duct the spiral organ nerve impulse conduction of sound: air conduction