Animal Tissue and Anatomy

The stapes is one of the three ossicles located in the middle ear, not the external ear. The pinna, ear canal, and ear drum are all components of the external ear structure.

The ear drum (tympanic membrane) is a thin membrane that vibrates in response to sound waves, playing a crucial role in transmitting sound to the middle ear.

The Eustachian tube is a canal that connects the middle ear to the nasopharynx, helping to equalize pressure.

The vestibule, cochlea, and three semicircular canals are all components of the inner ear (internal ear). The cochlea is responsible for hearing, while the vestibule and semicircular canals are involved in balance and equilibrium. The external ear collects sound, and the middle ear transmits it.

Each semicircular canal has a swollen end called the ampulla, which contains sensory receptors for detecting rotational movement. The vestibule and cochlea are separate structures of the inner ear. The ampulla houses the crista ampullaris with hair cells that detect head rotation.

The cochlea is a snail shell-shaped, spiral structure in the inner ear that contains the organ of Corti for hearing. It is filled with fluid and has hair cells that convert sound vibrations into nerve impulses. The vestibule is an adjoining chamber, and semicircular tubes are for balance, not shaped like a shell.

Otoliths are small calcium carbonate crystals found in the vestibule (utricle and saccule) near the hair cells. They help detect gravity and linear acceleration by their movement relative to the hair cells. Ossicles are ear bones, cristae are sensory ridges in ampullae, and cupula is a gelatinous structure.

Endolymph is the fluid that fills the membranous labyrinth including the vestibule, semicircular canals, and cochlea. It has a unique ionic composition similar to intracellular fluid (high potassium, low sodium) essential for hair cell function. Perilymph fills the space between membranous labyrinth and bone.

The oval window and round window are two membrane-covered openings between the middle and inner ear. The oval window receives vibrations from the stapes, while the round window releases pressure waves from the cochlea. There are no tubes by these names - they are windows (openings with membranes).

The membranous labyrinth is a complex system of interconnected tubes and sacs filled with endolymph within the bony labyrinth of the inner ear. It includes the cochlear duct, semicircular ducts, utricle, and saccule. It contains the sensory receptors for hearing and balance.

The vestibule contains two main sacs: the utricle and the saccule. The utricle is situated superiorly (upper part) to the saccule.

Basilar membrane

The organ of Corti, which contains the hair cells (auditory receptors), is located on the basilar membrane within the cochlea of the inner ear.