External Ear

1. Auricle:

• Single elastic cartilage.
• Covered by skin.
• Continuous medially with external auditory meatus.
• Innervation:
  • auriculotemporal nerve,
  • great auricular nerve.
• Lymphatic drainage:
• superficial parotid,
• mastoid, retroauricular,
• deep and superficial cervical lymph nodes.

2. External auditory meatus:

• Outer 1/3:
• S-shaped,
• cartilaginous,
• skin contains hairs,
• sebaceous and ceruminous glands.
• Inner 2/3:
• bony,
• narrower (isthmus).
• Inferior wall about 5 mm longer than superior wall due to obliquity of tympanic membrane.
• Innervation:
• auriculotemporal nerve,
• auricular branch of vagus.

Tympanic Membrane (Ear Drum)

• Semi-transparent oval membrane.
• Separates external and middle ears.
• Is obliquely placed.
• Handle of malleus attached to its inner side, resulting in concavity towards the external auditory meatus.
• Moves in response to air vibrations which are transmitted via middle ear bones to the inner ear.
• External surface is innervated mainly by the auriculotemporal nerve.

MODELS IN ANATOMY LAB