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Wednesday, November 9, 2011

Ear Functions and Structure - Lesson 278

In this post, we are going to learn about ear functions and structure. This lesson begins the ear anatomy and physiology lessons. In the future posts, we will learn about human ear anatomy and physiology. As per the passage of sound waves from the ear to the brain, we can divide the ear structure into four divisions, such as outer ear, middle ear, inner ear or labyrinth, and brain. The outer ear consists of pinna, external auditory ear, and tympanic membrane. The middle ear consists of malleus, incus, stapes, and oval window. The inner ear or labyrinth consists of cochlea, auditory liquids and receptors, and auditory nerves. In the brain, the ear is connected with cerebral cortex. We will learn about each of these parts of the ear one by one now.

Ear Functions and Structure:  Outer Ear: Any sound waves from our surrounding will enter into the outer ear first through the muscle part called pinna or auricle, outside the ear, which projects outside the ear. Auditory canal is extended from the pinna, which is also known as external auditory meatus. This canal is lined with some glands and those glands secrete a wax substance called cerumen. Cerumen is brownish-yellow in color. Cerumen lubricates the auditory canal. We will learn about ear functions and structure of the middle ear now.

Middle Ear: There is a membrane that obstructs the sound wave that travels from the outer ear to the inner ear called ear drum or tympanic membrane. Due to this obstruction, the ear drum vibrates and so three small bones present in the middle ear called malleus, incus, and stapes. The common name for these three small bones is ossicles. As the one of the small bone called stapes moves, it brings into touch with the oval window, which separates the middle and the inner ear.

Functions of Inner Ear: Inner Ear: The middle ear extends into the inner ear as cochlea, which is a snail-shaped structured bone. Cochlea consists of a lubricant liquid named as perilymph and endolymph. The sound vibrations from the middle ear passes through this structure and liquids. Organ of Corti is a sound receptor present in the inner ear. Sound waves from organ or Corti passes through auditory nerves present in the inner ear to brain.

Brain: Sound wave is received in the inner ear to the brain to the cerebral cortex and so the sound perception is felt by the human beings. The lesson of ear functions and structure concludes now.

In the next lesson, we wil learn about the function of the ear. Okay. Come on.

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