INTRODUCTION:

It is also known as Acoustica-vestibular-apparatus.
It is an organ of hearing and balancing in both static and kinetic conditions.
It consists of three parts:
1. External Ear.
2. Middle Ear.
3. Internal Ear.


1. EXTERNAL EAR:

It is consist of:

  • Pinna or auricle- It is the outer part of the ear.
  • External auditory canal or tube: It is the tube that connects the outer ear to the middle ear.
  • Tympanic membrane (eardrum)- It is a thin transparent membrane that divides the external ear from the middle ear.

2. MIDDLE EAR:

It is consist of:

a. Ossicles:

Ossicles are the small bones that are connected and transmit the sound waves to the inner ear. They are:
  • Malleus.
  • Incus.
  • Stapes.

b. Eustachian tube:

  • It is the canal that links the middle ear with the back of the nose.
  • It helps to equalize the pressure in the middle ear that is essential for the proper transfer of sound waves.
  • It is lined with mucous, just like the inside of the nose and throat.

3. INNER EAR:


The inner ear lies within the temporal bone in a complex cavity called the bony labyrinth. It is consists of: 
  • Cochlea- It is responsible for the sense of hearing.
  • Vestibule- It contains receptors for balance.
  • Semicircular canals- It is the organ responsible for dynamic balance.