Ear anatomy: anatomy of the outer, middle and inner ear
Generally speaking, the ear is divided into three parts: the outer ear, the middle ear and the inner ear. Each part of the ear performs individual functions. You can find out how the individual components of the ear are anatomically structured and how they are involved in the hearing process in this article.
Outer ear anatomy
The task of the outer ear is to modify the sound pressure and guide the received sound waves to the middle ear.
The components of the outer ear at a glance:
- Outer ear canal
- Tympanic membrane (also counted as part of the middle ear, depending on the source)
- Hammer process
Outer ear anatomy: auricle anatomy
The pinna, also known as the pinna, is the only part of the ear that is located outside the skull. When people talk about the ear in everyday language, they are usually referring to the externally visible pinna, even though it is only a part of the entire ear.
The pinna itself consists of cartilage covered by skin and is supported by ligaments and muscles of the outer ear. The explicit task of the pinna is to guide the incoming sound waves into the ear canal like a kind of funnel.
Outer ear anatomy: (Outer) ear canal anatomy
The external auditory canal is a 2-3 cm long canal that extends from the pinna to the eardrum. A smaller, outer (lateral) part of the ear canal is cartilaginous and has glands that are responsible for earwax production.
The remaining, inner (medial) part of the ear canal is bony and comparatively narrower than the outer part. The task of the external auditory canal is to guide sound to the eardrum.
Outer ear anatomy: eardrum
The eardrum is a thin, impermeable membrane that is always under tension and separates the outer and middle ear. The dural process, which is already part of the middle ear, is fused to the eardrum. When sound waves hit the eardrum, it is set into vibration. The vibration in turn transmits the sound via the malleus process to the malleus in the middle ear.
Middle ear anatomy
The middle ear is used for amplification in the hearing process.
The components of the middle ear at a glance:
- Eustachian tube
- Tympanic cavity (cavum tympani)
- Ossicles (malleus, incus, stapes)
Middle ear anatomy: tympanic cavity
Part of the middle ear is the tympanic cavity, a bony, air-filled cavity, which in turn houses the three aural ossicles. Hammer, Anvil and Stirrup are named after their shape and transmit the vibrations emanating from the eardrum to the oval window..
Middle ear anatomy: Eustachian tube (auditory tube)
The Eustachian tube, also known as the ear trumpet, serves to ventilate the middle ear and equalize pressure. Accordingly, it ensures the resilience of the eardrum. It also connects the middle ear with the nasopharynx (nasopharynx).
Pressure equalization through the Eustachian tube is particularly relevant for external pressure changes, such as when flying. If it is blocked, as in the case of a cold, pressure equalization is noticeably difficult.
Inner ear anatomy
The inner ear is where the conversion of sound waves into electrical impulses ultimately takes place. It also contains parts of the hearing and balance organ, which is responsible for the sense of balance and spatial orientation. The inner ear is located on the petrous bone.
Components of the inner ear at a glance:
- Cochlear labyrinth/cochlea with organ of Corti
- Vestibular labyrinth (organ of equilibrium)
- Hair cells
Inner ear anatomy: cochlea
The cochlea, also known as the cochlea, is a bony labyrinth. Starting from the middle ear, the vibrations of the eardrum reach the cochlea via the ossicles and the oval window.
Acoustic perception also requires the corti organ, which is located in the cochlea. This in turn contains hundreds of hair cells that convert mechanical vibrations into electrical signals. The resulting nerve impulses can ultimately be transmitted to the central nervous system so that hearing can take place.
Inner ear anatomy: organ of equilibrium
Three semicircular canals together with two macular organs form the vestibular apparatus. A fluid and hair cells are located within the semicircular canals. Rotational accelerations are perceived by the semicircular canals and a corresponding signal is transmitted to the brain by the resulting nerve impulses.The macular organs (sacculus and utriculus) also contain hair cells, which are surrounded by a mucous plug that is surrounded by fluid. If the position of the head is changed, the position of the mucus plug changes with it according to gravity. The hairs follow the direction and thus trigger nerve impulses, which signal the position change to the brain. For balance, however, the brain also uses information from the eyes and skin.