INTRODUCTION:

It consists of:
a. The auricle or pinna .
b. The external acoustic meatus.

A. AURICLE or PINNA:

  • The auricle is the part seen on the surface.
  • The greater part of it is made up of a elastic cartilage which is lined on both sides by skin.
  • The lowest part of the auricle is soft and consists only of fibrofatty tissue covered by skin.

B. EXTERNAL ACOUSTIC MEATUS:

  • It is a curved canal which conducts the sound waves from the external ear to tympanic membrane.
  • It is a “s” - shaped , divided into 3 - parts , External, Middle, Internal.
  • The canal is about 24mm long of which medial ⅔ rd is bony and the ⅓ rd is cartilaginous.
  • Due to the obliquity of the tympanic membrane, the anterior wall is longer than the posterior wall.
  • It is oval in section.
  • The bony part is formed by tympanic plate of the temporal bone.

BLOOD SUPPLY:

  • The outer part of the canal is supplied by the SUPERFICIAL TEMPORAL & POSTERIOR AURICULAR ARTERY.
  • The inner part is supplied by the DEEP AURICULAR BRANCH OF MAXILLARY ARTERY.

Nerve Supply: 

  • The outer half is supplied by AURICULAR TEMPORAL NERVE.
  • The inner half is supplied by the AURICULAR BRANCH OF VAGUS NERVE.

LYMPHATIC DRAINAGE:

The Lymphatics pass to the perpendicular and Superficial Cervical Lymph Nodes.

FUNCTIONS:

  • Hair function:- for filtration.
  • Mucus for making air moist.

APPLIED ANATOMY:

Boils and other infection of the external meatus cause the little swelling and pain due to the fixing of the skin to the bone and cartilaginous.