There are five distinct end organs of the vestibular apparatus:
- Three semicircular canals: anterior (superior), lateral (horizontal), posterior
- Two otolith organs: utricle and saccule
The membranous and bony labyrinth are embedded in the petrous bone. The membranous labyrinth is surrounded by perilymph, which is similar to extracellular fluid. Endolymph fills the vestibular end organs along with the cochlea, and is similar to intracellular fluid.
The bony labyrinth is a series of three cavities within the petrous temporal bone:
Figure 1. The vestibule is the central part of bony labyrinth, as shown in the figure below:
Redrawn from: Viswanatha B. Labyrinthectomy. Retrieved from https://emedicine.medscape.com/article/2051423-overview
Figure 2. Bony and membranous labyrinth
Redrawn from: Lee SC. Vestibular System Anatomy. Retrieved from https://emedicine.medscape.com/article/883956-overview
Figure 3. Vestibular apparatus showing the cristae of the ampullae of the semicircular canals, and the arrangement of otoconia on the macula of utricle and saccule.
