1. The Ear’s Role in Balance and Equilibrium

2. The Ear Houses two senses Hearing Equilibrium (balance)
Receptors are mechanoreceptors
Different organs house receptors for each sense

3. Anatomy of the Ear The ear is divided into three areas External ear
Middle ear
Inner ear

5. The External Ear Involved in hearing only
Structures of the external ear
Pinna (auricle)
External auditory canal

6. The Middle Ear Air-filled cavity within the temporal bone
Only involved in the sense of hearing
Two tubes are associated with the inner ear
The opening from the auditory canal is covered by the tympanic membrane
The auditory tube connecting the middle ear with the throat
Allows for equalizing pressure during yawning or swallowing
This tube is otherwise collapsed
Three bones span the cavity
Malleus (hammer)
Incus (anvil)
Stapes (stirrup)
Vibrations from eardrum move the malleus
These bones transfer sound to the inner ear

7. The Inner Ear or Bony Labyrinth
Includes sense organs for hearing and balance
Filled with perilymph
A maze of bony chambers within the temporal bone

8. Organs of the Inner Ear
Semicircular canals – organ for dynamic equilibrium
Cochlea – organ for hearing
Vestibule – organ for static equilibrium

11. Organs of Equilibrium Receptor cells are in two structures
Vestibule (static)
Semicircular canals (dynamic)
Equilibrium has two functional parts
Static equilibrium
Dynamic equilibrium

12. Static Equilibrium receptors are in the vestibule
Maculae – receptors on the membranes of the vestibule
Report on the position of the head
Send information via the vestibular nerve

13. Dynamic Equilibrium receptors are in the semicircular canals
Crista ampullaris – receptors in the semicircular canals
Tuft of hair cells
Cupula (gelatinous cap) covers the hair cells
Action of angular head movements
The cupula stimulates the hair cells
An impulse is sent via the vestibular nerve to the cerebellum

14. Review of the balance and equilibrium organs in the inner ear
STATIC EQUILIBRIUM – position of the head in space
The organ is the vestibule
The receptor inside the vestibule is the maculae
DYNAMIC EQUILIBRIUM – action of angular head movements
The organ is the semicircular canals
The receptor inside the semicircular canals is the crista ampullaris

15. Symptoms of Meniere’s Disease
The symptoms of Ménière’s disease are episodic rotational vertigo (attacks of a spinning sensation)
Hearing loss
Tinnitus (a roaring, buzzing, or ringing sound in the ear)
A sensation of fullness in the affected ear.

16. Meniere’s Disease
A disorder of the inner ear. Although the cause is unknown, it probably results from an abnormality in the fluids of the inner ear.
Ménière’s disease is one of the most common causes of dizziness originating in the inner ear.
In most cases only one ear is involved, but both ears may be affected in about 15 percent of patients.
Ménière’s disease typically starts between the ages of 20 and 50 years. Men and women are affected in equal numbers.