Inner Ear

Inner Ear (Labyrinth)

The inner ear consists of:

1. Bony Labyrinth:
   • Cochlea
   • Vestibule
   • Semicircular canals
2. Membranous Labyrinth:
   • Cochlear duct
   • Utricle and saccule
   • Semicircular ducts
   • Endolymphatic duct and sac

• The membranous labyrinth is filled with a clear fluid called endolymph
• while the space between membranous and bony labyrinths is filled with perilymph.

Bony Labyrinth

1. Vestibule:
   • Central part of the labyrinth.
   • Contains the oval window, saccule, and utricle.
2. Semicircular Canals:
   • Lateral, posterior, and superior.
   • Ampullated and nonampullated ends.
3. Cochlea:
   • Resembles a snail shell.
   • Coiled tube making 2.5 turns around the modiolus.
   • Contains three canals:
     • Scala vestibuli
     • Scala tympani
     • Scala media (cochlear duct)

Membranous Labyrinth

1. Cochlear duct
2. Utricle and saccule
3. Semicircular ducts
4. Endolymphatic duct and sac

Windows of the Inner Ear

1. Oval Window: Fixed with the footplate of the stapes.
2. Round Window: Covered by the secondary tympanic membrane.