window in the inner ear. The ear ossicles transmit sound waves to the inner ear. A tube called Eustachian tube connects the middle ear cavity with the pharynx. This tube helps in equalizing the pressure of air on either sides of the ear drum.
Inner ear is the fluid filled cavity consisting of two parts, the bony labyrinth and the membranous labyrinths. The bony labyrinth consists of three areas: cochlea, ve stibule and semicircular canals. The cochlea is a coiled portion consisting of chambers namely: scala vestibuli and scala tympani- these two are filled with perilymph; and the scala media is filled Auditory nevers Tectorial membrane Organ of Corti Perilymph Perilymph Endolymph Ear canal Eustachian tube Middle ear Round window Inner ear Malleus Incus Stapes Oval window Tympanum Air Sound Figure . Path of Sound wave XI Std Biology-Zoology Chapter- base of hair cells and the action potential is propagated to the brain as sound sensation through cochlear nerve.
Figure . Organ of Corti Defects of Ear Deafness may be temporary or permanent. It can be further classified into conductive deafness and sensory-neural deafness . Possible causes for conductive deafness may be due to i.
the blockage of ear canal with earwax, ii. Rupture of eardrum iii. Middle ear infection with fluid accumulation iv. Restriction of ossicular movement.In sensory-neural deafness , the defect may be in the organ of Corti or the auditory nerve or in the ascending auditory pathways or auditory cortex.
Organ of Equilibrium Balance is part of a sense called proprioception, which is the ability to sense with endolymph. At the base of the cochlea, the scala vestibule ends at the ‘oval window’ whereas the scala tympani ends at the ‘round window’ of the middle ear. The chambers scala vestibuli and scala media are separated by a membrane called Reisner’s membrane whereas the scala media and scala tympani are separated by a membrane called Basilar membrane (Figure . ) Organ of Corti The organ of Corti (Figure.
. ) is a sensory ridge located on the top of the Basilar membrane and it contains