External ear

• Air filled cavity
• Formed of following parts

a. Pinna

• Roughly funnel shaped supported by cartilage
• Collect sound from different direction.

 

b. Auditory canal

• Long tubular and oblique canal.
• Concentrates sound to strike on ear drum
• Anterior 1/3^rd supported by cartilage and posterior 2/3^rd by bone.

 

 

c. Ear drum

• Separates external ear from middle ear.
• When sound strike on it, then it vibrate freely.

 

Middle ear

• Air filled cavity/tympanic cavity.
• Communicate with pharynx by Eustachian tube which maintains equilibrium.
• Tympanic cavity contains three bones articulating each other.

They are

a. Malleus

• Largest hammer shaped bone
• Connected with eardrum.

 

b. Incus

• Middle smaller bone, anvil shaped.
• Connected with malleus and incus

 

c. Stapes

• Smallest inner bone, stirrup shape
• Connected with oval window.

 

Internal ear

• Liquid filled cavity
• Formed of membranous labyrinth and bony labyrinth.
• Contains two parts:

a. Vestibular parts

• Concerned with equilibrium filled with endolymph.
• Three semicircular canals converge.
• Works with visual system

 

b. Cochlear parts

• Concerned with hearing.
• Contains three canals

i. Vestibular canal

ii. Middle canal

iii. Tympanic canal

      Middle canal contains organ of corti formed of numerous auditory phonoreceptors cells.