Inner Ear Anatomy

bony labyrinth

intercommunicating bony cavities located in the inner ear filled with perilymph

membranous labyrinth

closed system of membranous tubes/sacs/ducts inside the bony labyrinth. filled with endolymph

vestibular system

semicircular canals, utricle, saccule. located next to the cochlea. allow sensation of rotation/motion/balance

semicircular canals

three fluid-filled canals (loopy things) that sense rotational head movements

anterior/superior semicircular canal

detects "nodding yes" movement. non-ampullated end unites with non-ampullated end of posterior SCC to form the crus commune

posterior semicircular canal

Detects tilting the head to the side, or cartwheels. lower ampullated end communicates w the vestibule

lateral semicircular canal

both ends open into vestibule

ampullae

bulbous expansions at the base of each canal in the inner ear that contain the sensory organs for balance and head rotation

otoliths (ear rock)

sit in ampullae surrounded by hair cells. as head moves, otoliths stimulate hair cells which send signals to brain of movement.

utricle

the larger of two sacs within the membranous labyrinth of the vestibule in the inner ear

saccule

the smaller of two sacs within the membranous labyrinth of the vestibule in the inner ear

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

helicotrema (spiral hole)

the opening that connects the scala vestibuli and scala tympani chambers at the apex of the cochlea.

modiolus

bony core that cochlear canal spirals around. elongated cone

scala vestibuli/vestibular duct

perilymph-filled top chamber of cochlea. Closest to vestibular system.

scala tympani

perilymph-filled cochlear chamber that connects to the round window

scala media

Middle chamber of the cochlea; filled with endolymph

perilymph

fluid that fills the bony labyrinth of the inner ear

endolymph

fluid within the membranous labyrinth of the inner ear

stria vascularis

external wall of cochlear duct composed of mucosa that secretes endolymph

Reissner's membrane (vestibular membrane)

membranous separation between scala vestibuli and scala media

spiral lamina

bony shelf that projects from the modiolus

spiral ligament

fibrous connective tissue on the lateral wall of the cochlear duct that supports the lateral edge of the basilar membrane

spiral limbus

ridge of fibrous connective tissue that connects to tectorial membrane

basilar membrane

runs the length of the cochlea in the inner ear and holds the hair cells.

organ of corti

Center part of the cochlea, containing hair cells, canals, and membranes

tectorial membrane

gelatinous, ribbon-like structure sitting atop the organ of corti

tunnel/pillars of corti

triangular part of corti (space=tunnel, pillars=pillars)

inner hair cells

neurons in the organ of Corti; responsible for auditory transduction

outer hair cells

neurons in the organ of Corti; serve to amplify and sharpen the responses of inner hair cells