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The Ear

The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

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Page 1: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The Ear

Page 2: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Functions of the Ear

1. Hearing2. Balance

There are three parts to the Ear:

1.The Outer Ear

2.The Middle Ear

3.The Inner Ear

Page 3: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Anatomy of Ear

•Auditory canal•Tympanic membrane•Pinna•Ossicles•Oval window•Round window•Cochlea

•Organ of Corti•Semicircular canals•Utricle•Saccule•Otoliths•Auditory nerve•Outer/middle/inner ear

Page 4: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 5: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Ear Anatomy…

Page 6: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 7: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Anatomy of the Ear

Outer Ear Function: To gather sound waves,

causing the ear drum to vibrate. Made of skin and cartilage. The ear flap is called the pinna.

Page 8: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Outer EarPinna

Ear flap (cartilage) Funnels sound into auditory canal

Auditory Canal Leads into the head Lined with wax secreting cells

Tympanic Membrane (aka. Ear Drum) End of the auditory canal Separates outer ear from middle

ear

Page 9: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 10: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 11: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 12: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Mid

dle

Ear

The Eardrum is connected to the three smallest bones in the body:-Malleus (hammer)- Incus (anvil)- Stapes (stirrup)

Together these are known as the ossicles.

Page 13: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 14: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Mid

dle

Ear The bones are attached to each

other by ligaments that allow them to move back and forth & AMPLIFY the sound!

The last ossicle, the stirrup, is attached to the oval window.

Page 15: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Sound Intensity and Pitch

Sound intensity - depends on number of neurons and frequency of firing

Pitch (hi or low note) - each hair cell responds to only one frequency.

Page 16: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Ear Test

Page 17: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The eustachian tube is located just after the eardrum, in the middle ear.

The Eustachian tube connects to the throat and allows for pressure equalization on both sides of the tympanic membrane.

How do we equalize pressure?

Mid

dle

Ear

Page 18: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Size of tube compared to coin

Page 19: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 20: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Inner Ear

Function#1: Hearing. Converts sound vibrations from the ossicles into nerve impulses!!!

Function #2: Balance. The Cochlea is the organ that is

responsible for hearing (this is the place where neurons attach).

The Cochlea is coiled, like a snail shell.

It is divided into scala vestibule and scala tympani by the cochlear duct.

Page 21: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 22: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Cochlea – Cross Section

Page 23: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Inner Ear

Page 24: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The cochlear duct contains the Organ of Corti where sound receptors (four rows of hair cells) are found.

A fluid (called endolymph) surrounds the Organ of Corti.

The scala vestibuli and the scala tympani contain another fluid called perilymph.

The utricle, saccule, and semicircular canals are responsible for balance and body position

Page 25: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 26: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The Mechanics of Hearing

Longitudinal sound waves travel down the auditory canal.

Tympanic membrane vibrates. Ossicles (malleus, incus, & stapes)

move. Stapes is connected to the oval

window. When the stapes moves, it causes this window to bulge.

The oval window bulging causes the fluid in the outer two parts of the cochlea to move.

This puts pressure on the cochlear duct.

Page 27: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The Mechanics of Hearing

The pressure waves cause the basilar membrane to move which causes the hairs in the organ of Corti to bend against the tectorial membrane.

As the hairs bend, the small nerves that are connected to the base of the hairs are stimulated.

These nerve impulses are carried to the brain along the auditory nerve.

the temporal lobe of the cerebral cortex interprets the impulses as sound.

Page 28: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 29: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 30: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 31: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear
Page 32: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The Mechanics of Balance

The utricle, saccule, and semicircular canals are important structures for balance & are filled with fluid and contain sensory hairs.

The utricle & saccule contain small calcium carbonate particles called otoliths (ear stones).

Movement of the head ( along one plane – horizontal/vertical), causes the otoliths to move in response to gravity. These particles cause sensory hairs to bend, triggering impulses which alert the brain as to the position of the head.

The saccule contains sensory hairs as well

Page 33: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

The Mechanics of Balance

The semicircular canals contain sensory hairs which are bent by movement in the fluid surrounding them. One canal detects bending forward and backward, another detects bending left or right, and a third detects a turning motion.

The brain then signals the appropriate muscles to maintain balance.

Page 34: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Semicircular Canals

Page 35: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

Ear SafetySmall muscles in your ears help

protect your hearingWhen loud noises are around,

1. Muscles attached to the hammer (malleus) contract and restrict intense movements.

2. A second muscle contracts pulling the stirrup (stapes) away from the oval window limiting inner ear damage.

Not effective with sudden loud noises This response takes time. Sudden noise causes huge damage to

inner ear, specifically the hairs in the Organ of Corti

Page 36: The Ear. Functions of the Ear 1. Hearing 2. Balance There are three parts to the Ear: 1.The Outer Ear 2.The Middle Ear 3.The Inner Ear

What structures are for hearing?