The Ear: • It is the organ that detects sound. • It not only receives sound, but also aids in balance and body position. • Part of the auditory system. • Transforms sound waves (air pressure) into electrical impulses in the brain Outer Ear: • Includes: • The pinna or auricle (the fleshy visible outer ear) • The ear canal • The outer layer of the tympanic membrane (ear drum) Middle Ear: • An air-filled cavity behind the tympanic membrane, includes three bones (ossicles): • The malleus; or hammer • Incus; or anvil • Stapes; or stirrup • Connects to the throat via the Eustachian tube Inner Ear: • Responsible for sound detection and balance • it consists of the bony labyrinth, a hollow cavity in the skull with a system of passages comprising two main functional parts: • The cochlea, dedicated to hearing • The vestibular system, dedicated to balance o The Cochlea: Auditory portion of the inner ear o Spiral-shaped coil o Inside the bony labyrinth o Filled with a watery liquid o As the fluid moves, the Organ of Corti moves o Organ of Corti: the structure that transduces pressure waves to action potentials o Specific fibers resonate to sound frequencies and cause Hair Cells to move, which send signals through the Cochlear Nerve onto the brain o Louder Sounds cause more Hair Cells to move o Our Brains interpret all this raw data Balance (Vestibular System): • Balance is controlled through signals to the brain from your eyes, the inner ear, and the sensory systems of the body (such as the skin, muscles, and joints). • This balance system is also known as the vestibular system. • In the inner ear, the balance system consists of three canals (semicircular canals) • Semicircular shape • contain fluid • “sensors” that detect rotational movement of the head. • Each canals lies at a different angle and is situated at a right angle to each other. • deal with different movement: up-and-down, side-to-side, and tilting from one side to the other. • All contain sensory hair cells that are activated by movement of inner ear fluid (endolymph). • As the head moves, hair cells in the semicircular canals send nerve impulses to the brain by way of the acoustic nerve. • The nerve impulses are processed in the brain to help us know where we are in space or if we are moving. • Located near the semicircular canals are the utricle and the saccule. • The ends of the semicircular canals connect with the utricle, • the utricle connects with the saccule. • The semicircular canals provide information about movement of the head. • The sensory hair cells of the utricle and saccule provide information to the brain about head position when it is not moving. • The utricle is sensitive to change in horizontal motion

1. The Ear
Valentina Herrero, Felipe De la Garza, Mariana Calderon

2. Table of contents
The ear:
Parts of the ear
-Outer
-Middle
Ossicles
-Inner
Cochlea
Balance
Drawing

3. The ear…
• It is the organ that detects sound.
• It not only receives sound, but also aids in
balance and body position.
• Part of the auditory system.
– Transforms sound waves
(air pressure) into electrical
impulses in the brain.

4. Outer ear
• The shape of the outer ear of mammals varies
widely across species…
• The most external portion of the ear.
• Includes:
– The pinna or auricle (the fleshy visible outer ear)
– The ear canal
– The outer layer of the tympanic membrane (ear
drum)

5. Ear Canal

6. Middle ear
• An air-filled cavity behind the tympanic membrane,
includes three bones (ossicles):
– The malleus; or hammer
– Incus; or anvil
– Stapes; or stirrup
• The three ossicles transmit sound from the tympanic
membrane to the ventricles of the ear.
• In humans and other land animals the middle ear
(like the ear canal) is normally filled with air.
– Connects to the throat via the Eustachian tube

7. Ossicles
• The malleus is connected to the tympanic
membrane, and transmits vibrations of the
membrane produced by sound waves.
• The incus is the bridge between the malleus and
stapes.
• The stapes connects to the oval window, and is
the smallest named bone in the human body.
• The ossicles help in amplification of
sound waves by nearly thirty times.

9. Ear Canal

10. Inner ear
• …However the inner workings of mammalian
ears (including humans') are very similar.
• responsible for sound detection and balance
• it consists of the bony labyrinth, a hollow
cavity in the skull with a system of passages
comprising two main functional parts:
– The cochlea, dedicated to hearing
– The vestibular system, dedicated to balance

11. The cochlea
• Auditory portion of the inner ear
• Spiral-shaped coil
• Inside the bony labyrinth
• Filled with a watery liquid
• As the fluid moves, the Organ of Corti moves
• Organ of Corti: the structure that transduces
pressure waves to action potentials

12. The cochlea
• Specific fibers resonate to sound frequencies
and cause Hair Cells to move, which send
signals through the Cochlear Nerve onto the
brain
• Louder Sounds cause more Hair Cells to move
• Our Brains interpret all this raw data

14. Ear Canal

15. Inner Ear: Balance
• Balance is controlled through signals to the
brain from your eyes, the inner ear, and the
sensory systems of the body (such as the skin,
muscles, and joints).
• This balance system is also known as the
vestibular system.

16. Vestibular System
• In the inner ear, the balance system consists of
three canals (semicircular canals)
– Semicircular shape
– contain fluid
– “sensors” that detect rotational movement of the
head.
– Each canals lies at a different angle and is situated at a
right angle to each other.
– deal with different movement: up-and-down, side-to-side,
and tilting from one side to the other.

17. Vestibular System
– All contain sensory hair cells that are activated by
movement of inner ear fluid (endolymph).
• As the head moves, hair cells in the
semicircular canals send nerve impulses to the
brain by way of the acoustic nerve.
• The nerve impulses are processed in the brain
to help us know where we are in space or if
we are moving.

18. Vestibular System
• Located near the semicircular canals are the
utricle and the saccule.
• The ends of the semicircular canals connect with
the utricle,
• the utricle connects with the saccule.
• The semicircular canals provide information
about movement of the head.
• The sensory hair cells of the utricle and saccule
provide information to the brain about head
position when it is not moving.
• The utricle is sensitive to change in horizontal
motion

19. pinna
Ear drum
Semicircular Canals
Cochlea
Middle
Ear
Bones
Eustachian tube