Quick Facts
The bony labyrinth is the interconnected cavities and canals in the petrous portion of the temporal bone, in which the membranous labyrinth, the vestibular aqueduct, and the cochlear aqueduct are lodged; it consists of three parts: the vestibule, the semicircular canals, and the cochlea (Dorland, 2011).
Structure and/or Key Feature(s)
The internal ear is located in the petrous part of the temporal bone, where the bone is of a harder consistency than the remaining petrous bone. It consists of a network of inner cavities which are lined by periosteum. These cavities are the cochlea, vestibule, and semicircular canals, which are collectively known as the bony labyrinth. The membranous labyrinth lies within these bony cavities and is separated from the inner aspect of the bony wall by periosteum and perilymph.
The bony walls of the cochlea are quite porous and contain small canaliculi/micropores. These are mostly found in the osseous spiral lamina and the base of the scala tympani, with fewer found in the scala vestibuli. These canaliculi would appear to provide an extensive communication channel for the fluid between these structures (Standring, 2016).
The bony wall is primarily supplied via the cochlear branches of the labyrinthine artery, which typically originates from the basilar artery, but may originate from the anterior inferior cerebellar artery in some cases. Venous drainage occurs alongside the arterial supply, forming the labyrinthine vein which drains into the inferior petrosal or transverse venous sinuses.
Anatomical Relations
The internal aspects of the bony wall are lined with periosteum. The external aspect is consistent with the petrous part of the temporal bone, and the lateral aspect is in contact with the middle ear via the stapes.
Function
The bony labyrinth is the foundation of the structural architecture of the internal ear and the auditory pathways. It protects the membranous labyrinth and its nerve cells to enable successful auditory transmission. It also serves as a protective barrier of possible foreign bodies/pathogens from the middle ear.
List of Clinical Correlates
—Otosclerosis
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice., 41st edition. Elsevier Limited
