2-The semicircular canals 3-The cochlea They are lined by endosteum and contain a clear fluid called the perilymph The vestibule is the central part of the bony labyrinth .In its lateral wall is the fenestra vestibule (oval window) which is closed by the base of stapes,and the fenestra cochleae (round window) which is closed by secondary tympanic membrane. Logged within the vestibule are the saccule and utricle of the membranous labyrinth There are three semicircular canals,superior,posterior and -open in posterior part of the vestibule by five orifices The superior and posterior are vertical while the lateral semicircular canal is set in horizontal position The cochlea resembles a snail shell,it opens in the anterior part of the vestibule.It consists of a centeral pillar(the modiolus) around which a tube makes two and one half spiral turn.The cochlea is divided by a membrane into scala vestibule above and scala tympani below Membranous labyrinth It is logged within the bony labyrinth and filled with endolymph and surrounded by perilymph and consists of utricle and saccule which are logged in the bony vestibule,also contain three semicircular ducts which lie within the bony semicircular canals,also contain the duct of cochlea which lie within the bony cochlea Physiology of hearing Airborne sound consists of vibration of the atmosphere and the purpose of auditory apparatus is toconvert this vibrations in air to vibrations in the inner ear fluid,and then to nerve impulses to be transmitted along the auditory nerve to the higher centrese of hearing.
2-The semicircular canals 3-The cochlea They are lined by endosteum and contain a clear fluid called the perilymph The vestibule is the central part of the bony labyrinth .In its lateral wall is the fenestra vestibule (oval window) which is closed by the base of stapes,and the fenestra cochleae (round window) which is closed by secondary tympanic membrane. Logged within the vestibule are the saccule and utricle of the membranous labyrinth There are three semicircular canals,superior,posterior and -open in posterior part of the vestibule by five orifices The superior and posterior are vertical while the lateral semicircular canal is set in horizontal position The cochlea resembles a snail shell,it opens in the anterior part of the vestibule.It consists of a centeral pillar(the modiolus) around which a tube makes two and one half spiral turn.The cochlea is divided by a membrane into scala vestibule above and scala tympani below Membranous labyrinth It is logged within the bony labyrinth and filled with endolymph and surrounded by perilymph and consists of utricle and saccule which are logged in the bony vestibule,also contain three semicircular ducts which lie within the bony semicircular canals,also contain the duct of cochlea which lie within the bony cochlea Physiology of hearing Airborne sound consists of vibration of the atmosphere and the purpose of auditory apparatus is toconvert this vibrations in air to vibrations in the inner ear fluid,and then to nerve impulses to be transmitted along the auditory nerve to the higher centrese of hearing.
pubdoc_10_28527_291.docx