External Auditory Meatus: Structure, Parts, And Features

External Auditory Meatus: Structure, Parts, And Features

External Auditory Meatus.
Answer:

• It is S-shaped
• It is about 24 mm long of which
• Medial 2/3rd or 16 mm is bony
• Lateral 1/3rd or 8 mm is cartilaginous
• It is oval in section
• The bony part is narrower than the cartilaginous part

External Auditory Meatus Parts:

1. Outer part

• Directed medially, forwards & upward

2. Middle part

• Directed medially, backwards & upward

3. Inner part

• Directed medially, forward & downward

1. Bony part:
   • It is formed by the tympanic plate of the temporal bone
   • It is C-shaped in cross section
2. Cartilaginous part:
   • It is C-shaped in section
   • The gap of the C is filled with fibrous tissue
   • The lining skin contains hair. Sebaceous glands & ceruminous or wax glands

External Auditory Meatus Blood supply:

• Outer part
  • Supplied by superficial temporal & posterior auricular arteries
• Inner part
  • Deep auricular branch of the maxillary artery

Nerve supply:

• Anterior half
  • Auriculotemporal nerve
• Posterior half
  • Auricular branch of vagus