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Ear Anatomy

Ear Anatomy

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This lesson will give an overview of the anatomy of the human ear.

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Tutorial

What's Covered

Welcome to this lesson today on ear anatomy. Today you will be learning about the structure and function of the ear. Specifically you will look at:

  1. Function & Structure
  2. Outer Ear
  3. Middle Ear
  4. Inner Ear

1. Function & Structure of the Ear

The function of the ear is to detect sound and sound travels as a wave. Within your ear are several structures that are able to detect sound waves and then interpret them; and sound is measured in a unit called decibels.


2. Outer Ear

The first main area of your ear is called the outer ear which is composed of the part of your ear that you can see from the outside as well as the auditory canal. The auditory canal’s purpose is to direct sound waves inward. Toward the organs and receptors of hearing.

Term to Know

    • Outer Ear
    • Anatomically the outer part of the ear that traps and funnels compressed air inward toward the middle ear. Anatomic structures included are the auricle/pinna, auditory canal.

3. Middle Ear

The next part of the ear you're going to take a look at is the middle ear which contains the tympanic membrane, which is also commonly known as the eardrum. Basically, when a sound wave enters the ear, through the auditory canal, it will strike the tympanic membrane causing it to vibrate. In turn this causes three small bones called auditory ossicles to vibrate which plays a crucial role in hearing. These three bones often times are nicknamed the hammer, anvil, and footplate or stirrup based on their shapes.

Terms to Know

    • Middle Ear
    • The middle portion of the ear that is primarily designed to mechanically amplify the sound waves that enter the ear. Anatomic structures included are the tympanic membrane (ear drum), auditory ossicles (malleus, incus, stapes), and the eustachian tube.
    • Tympanic Membrane
    • A thin, highly innervated tissue at the end of the auditory canal that is attached to the auditory ossicles. When sound waves strike the tympanic membrane it vibrates, which causes the auditory ossicles to shift and press against the cochlea. Commonly referred to as the "ear drum."
    • Auditory Canal
    • Otherwise known as the ear canal and a part of the outer ear; the auditory canal guides sound waves toward the tympanic membrane.

4. Inner Ear

The inner ear is where the actual detection of sound with sensory receptors occurs. Once the sensory receptors, also called hair cells, are activated their associated neurons will send signals to the brain so we can voluntarily process sounds at the cerebral cortex.

Term to Know

    • Inner Ear
    • The inner portion of the ear deeply embedded within the temporal bone; contains the organs of hearing and balance/equilibrium. Organs within the inner ear are the cochlea, the vestibular system, organ of Corti, tectorial membrane, hair cells (stereocilia), round window, otolith organs, auditory nerve, and the semicircular canals.

Your inner ear is also composed of several different structures that are crucial to hearing and the major organ that contains all of these structures is called the cochlea.The cochlea is a coiled structure and the cochlea contains several different structures, including the organ of Corti and the tectorial membrane.

The organ of Corti has little hair cells, which are mechanoreceptors, and they interact with the tectorial membrane, which helps to detect the intensity of a sound. The cochlea has another structure that aids in its function known as the round window. The round window basically acts as a pressure release valve if too much pressure builds up in the ear. The auditory nerve is what carries information to your brain once hair cells are activated and one thing to keep in mind is that different decibel levels will affect the hair cells are activated and how information is sent to the brain.

Above your auditory nerve you have your semicircular canals; you actually have three of them. Semicircular canals and the vestibular apparatus play roles in balance and equilibrium. The vestibular apparatus is composed of the semicircular canals and two fluid filled sacs, which will help maintain equilibrium. Otolith organs are bits of calcium carbonate within the fluid filled sacs of the vestibular apparatus that move as the head's position in space changes.

Example If you were to turn your head to the side, the otolith organs shift to the side as well, allowing the head's movement and position in space to be detected.

Terms to Know

    • Cochlea
    • The organ of hearing found within the inner ear; contains the sensory receptors for hearing (hair cells/stereocilia), organ of Corti, tectoral membrane, round window and the auditory nerve.
    • Organ of Corti
    • A highly specialized organ found within the cochlea that contains the hair cells/stereocilia and their supporting structures (tectoral membrane, basilar membrane).
    • Hair Cells
    • The actual receptors for hearing within the cochlea; the hair cells bend due to mechanical fluid vibrations within the cochlea. The bending of the hair cells causes them to depolarize and generate action potentials. The hair cells are also called stereocilia.
    • Tectorial Membrane
    • One of two gel membranes located within the cochlea of the ear and is part of the organ of Corti. The two gel membranes contribute to the mechanical process of hearing.
    • Semicircular Canals
    • A system of canals in the vestibular system of the inner ear that provide feeback about body position.
    • Vestibular Apparatus
    • A system within the inner ear that provides us with feedback about our body position and balance; consists of the semicircular canals and the otolith organs.
    • Auditory Nerve
    • The nerve that projects auditory information detected by the hair cells in the cochlea to the primary auditory cortex of the temporal lobe.
    • Round Window
    • A structure in the cochlea that acts to dampen the mechanical fluid vibrations within the cochlea to prevent damage to the hair cells.
    • Otolith Organs
    • The saccule and utricle, each with an otolith (hard bits of calcium carbonate).
    • Decibel
    • A unit of measurement which indicates the loudness of a sound.

Summary

So, this lesson has been an overview on anatomy of the ear. Specifically, you learned about the function and structure of the ear, specifically looking at the outer, middle, and inner ear.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Decibel

    A unit of measurement which indicates the loudness of a sound.

  • Otolith Organs

    The saccule and utricle, each with an otolith (hard bits of calcium carbonate).

  • Auditory Canal

    Otherwise known as the ear canal and a part of the outer ear; the auditory canal guides sound waves toward the tympanic membrane.

  • Round Window

    A structure in the cochlea that acts to dampen the mechanical fluid vibrations within the cochlea to prevent damage to the hair cells.

  • Auditory Nerve

    The nerve that projects auditory information detected by the hair cells in the cochlea to the primary auditory cortex of the temporal lobe.

  • Vestibular Apparatus

    A system within the inner ear that provides us with feedback about our body position and balance; consists of the semicircular canals and the otolith organs.

  • Semicircular Canals

    A system of canals in the vestibular system of the inner ear that provide feeback about body position.

  • Tectorial Membrane

    One of two gel membranes located within the cochlea of the ear and is part of the organ of Corti. The two gel membranes contribute to the mechanical process of hearing.

  • Hair Cells

    The actual receptors for hearing within the cochlea; the hair cells bend due to mechanical fluid vibrations within the cochlea. The bending of the hair cells causes them to depolarize and generate action potentials. The hair cells are also called stereocilia.

  • Organ of Corti

    A highly specialized organ found within the cochlea that contains the hair cells/stereocilia and their supporting structures (tectoral membrane, basilar membrane).

  • Tympanic Membrane

    A thin, highly innervated tissue at the end of the auditory canal that is attached to the auditory ossicles. When sound waves strike the tympanic membrane it vibrates, which causes the auditory ossicles to shift and press against the cochlea. Commonly referred to as the "ear drum."

  • Cochlea

    The organ of hearing found within the inner ear; contains the sensory receptors for hearing (hair cells/stereocilia), organ of Corti, tectoral membrane, round window and the auditory nerve.

  • Inner Ear

    The inner portion of the ear deeply embedded within the temporal bone; contains the organs of hearing and balance/equilibrium. Organs within the inner ear are the cochlea, the vestibular system, organ of Corti, tectorial membrane, hair cells (stereocilia), round window, otolith organs, auditory nerve, and the semicircular canals.

  • Middle Ear

    The middle portion of the ear that is primarily designed to mechanically amplify the sound waves that enter the ear. Anatomic structures included are the tympanic membrane (ear drum), auditory ossicles (malleus, incus, stapes), and the eustachian tube.

  • Outer Ear

    Anatomically the outer part of the ear that traps and funnels compressed air inward toward the middle ear. Anatomic structures included are the auricle/pinna, auditory canal.