Understanding how the ear functions
Hyderabad: This is in continuation to the last article focusing on sense organs. In today’s article, we will learn further about the ear’s functioning. The ear • The bony labyrinth in the ear is a series of channels. • Inside these channels lies the membranous labyrinth, which is surrounded by a fluid called perilymph. • […]
Hyderabad: This is in continuation to the last article focusing on sense organs. In today’s article, we will learn further about the ear’s functioning.
The ear
• The bony labyrinth in the ear is a series of channels.
• Inside these channels lies the membranous labyrinth, which is surrounded by a fluid called perilymph.
• The membranous labyrinth is filled with a fluid called endolymph.
• The coiled portion of the labyrinth is called cochlea.
• The membranes constituting cochlea, the reissner’s and basilar, divide the surrounding perilymph filled bony labyrinth into an upper scala vestibuli and a lower scala tympani.
• The space within cochlea called scala media is filled with endolymph. At the base of the cochlea, the scala vestibuli ends at the oval window, while the scala tympani terminates at the round window which opens to the middle ear.
• The organ of corti is a structure located on the basilar membrane, which contains hair cells that act as auditory receptors.
• The hair cells are present in rows on the internal side of the organ of corti.
• The basal end of the hair cell is in close contact with the afferent nerve fibres.
• A large number of processes called stereo cilia are projected from the apical part of each hair cell.
• Above the rows of the hair cells is a thin elastic membrane called tectorial membrane.
• The inner ear also contains a complex system called vestibular apparatus, located above the cochlea.
• The vestibular apparatus is composed of three semi-circular canals and the otolith (macula is the sensory part of saccule and utricle).
• Each semi-circular canal lies in a different plane at right angles to each other.
• The membranous canals are suspended in the perilymph of the bony canals.
• The base of canals is swollen and is called ampulla, which contains a projecting ridge called crista ampullaris which has hair cells.
• The saccule and utricle contain a projecting ridge called macula.
• The crista and macula are the specific receptors of the vestibular apparatus responsible for maintenance of balance of the body and posture.
To be continued…
