Question

Please type answer

Explain functions of these structures:

a. Outer Ear: pinna, external auditory meatus (ear canal), tympanic membrane

b. Middle ear: oval window, round window, eustachian tube, malleus, incus, stapes

c. Inner ear: perilymph, endolymph, cochlea, vestibule, semicircular canals, ampulla

d. Organ of Corti: hair cells, basilar membrane, tectorial membrane, helicotrema

e. Vestibular apparatus:

f.Otolith organs (utricle and saccule): Maculae, otoliths, hair cells

g. Semicircular canals: crista ampullaris, Cupula (gelatinous cap), hair cells

Answer 1

1.Pinna: It directs the sound to the ear. It protects external auditory meatus.

External auditory meatus:It transmit sound from pinna to tympanic membrane. It protects tympanic membrane.

Tympanic membrane: It is boundary between outer ear and middle ear. It protects middle ear. It helps in inpedence matching.

2.Oval window:sound vibrations are transmitted through the footplate of stapes to the oval window.

Round window:This connects scala tympani with the middle ear. Electrodes of cochlear implant are introduced through this and placed in scala tympani.

Eustachian tube:It helps in ventilation and pressure regulation of middle ear. It protects middle ear from nasopharyngeal secretions and sound pressures.

Malleus, incus, stapes: These are the auditory ossicles in the middle ear They transmit mechanical vibration of tympanic membrane to oval window. They increase force of vibrations and decrease the amplitude.

3.Perilymph:It fills within bony labyrinth. Similar to ecf composition and rich in sodium. It protects membranous labyrinth.

Endolymph:It is fluid in membranous labyrinth rich in potassium. It stimulate receptor cells which help to translate movement into nerve impulse.

Cochlea:It will transform vibration of cochlear fluids an d other structures into nerve signal.

Vestibule:detect changes in the linear acceleration.

Semicircular canal:helps to keep balance.

Ampula: provide spatial orientation.

4.Hair cells:There are 2 types-inner and outer hair cells. Inner hair cells transmit auditory stimuli. Outer hair cells modulate the function of inner hair cells and generate otoaccoustic emission.

Basilar membrane:It separates scala media from scala tympani.

Tectorial membrane:plays important role in transforming sound to mechanical stimulation

Helucotrema:It is the area where scala vistibuli meets scala media.