Auditory ossicles: The three tiny bones serving as transmitters of vibrations and located in the middle ear, called the malleus (hammer), incus (anvil), and stapes (stirrup).
Auditory tube: Passage to the pharynx that equalizes pressure between the middle ear and the atmosphere. Also called the pharyngotympanic, or Eustachian tube.
Bony labyrinth: Bony canal of the inner ear in the temporal bone.
Cochlea: Snail-shaped chamber of the bony labyrinth that contains three membranous tubes: the scala vestibuli, which is filled with perilymph and leads from the oval window to the apex, the scala tympani, which is filled with perilymph and leads from the apex to the round window, and the cochlear duct, which is filled with endolymph and is a closed tube. The organ of Corti is the receptor organ for hearing within the cochlear duct, which rests on the basilar membrane that is set into resonance when sound waves are absorbed, and these vibrations activate the hearing receptor cells.
Crista ampullaris: Sensory receptor organ for dynamic equilibrium in the ampulla of semicircular canals.
External acoustic meatus: The S-shaped tube that leads to the eardrum. Also called auditory canal.
Macula: Sensory receptor organ for balance and static equilibrium in the saccule and utricle of the vestibule.
Membranous labyrinth: A complex of membranous tubes suspended within the bony labyrinth, filled with endolymph and surrounded by perilymph.
Otoliths: Ear stones; grains of calcium carbonate in the maculae.
Oval window: A small, membrane-covered opening that transmits the vibratory motion of the stapes to the fluid in the scala vestibuli of the inner ear.
Pinna: The flesh covered elastic cartilage of the ear located on the sides of the head. Also called auricle.
Round window: A small, membrane-covered opening that acts as a pressure relief valve for the increased fluid pressure in the scala tympani as it bulges into the tympanic cavity.
Semicircular canals: Three semicircular channels in the bony labyrinth of the inner ear for the sense of dynamic equilibrium.
Tympanic membrane: Thin partition of fibrous connective tissue between the external auditory meatus and the middle ear. Also called eardrum.
Vestibule: Cavity in the middle of the bony labyrinth for the sense of balance and static equilibrium.