Middle Ear

Q: Which nerves form the tympanic plexus?

The tympanic plexus (plexus tympanicus) is formed by branches of the glossopharyngeal nerve. The primary nerve contributing to this plexus is: Tympanic nerve (n. tympanicus) — arises from the inferior ganglion of the glossopharyngeal nerve, enters the tympanic cavity, and forms the tympanic plexus (Jacobson's nerve).

Q: What is the handle of the malleus fused with?

The handle of the malleus (manubrium mallei) is anatomically fused with the tympanic membrane.

Q: Where is the base of the stapes fixed?

The base of the stapes (basis stapedis) is anchored in the vestibular window (fenestra vestibuli).

Auris media

For medical students2 min readUpdated 2026-10-10

The middle ear is a complex system of air-filled cavities that conducts and amplifies sound waves. It serves as a vital bridge transmitting acoustic energy to the structures of the internal ear.

ComponentsTympanic cavity, auditory ossicles, pharyngotympanic tube

LocationPetrous part of the temporal bone

MusclesTensor tympani and stapedius muscles

FunctionAmplification and transmission of sound vibrations

Tympanic Cavity

The tympanic cavity (cavitas tympanica) is the central space of the middle ear, located within the petrous part of the temporal bone. It is completely lined internally by a mucous membrane (tunica mucosa cavitatis tympani).

The tympanic cavity has six walls:

Membranous wall (paries membranaceus);
Labyrinthine wall (paries labyrinthicus);
Jugular wall (paries jugularis);
Carotid wall (paries caroticus);
Mastoid wall (paries mastoideus);
Roof of the tympanic cavity (tegmen tympani).

The cavity has important anatomical communications: anteriorly, it connects to the nasopharynx via the pharyngotympanic tube, and posteriorly, it communicates with the mastoid antrum (antrum mastoideum).

Auditory Ossicles

Within the tympanic cavity lie the auditory ossicles (ossicula auditus). They form a continuous mobile chain whose main function is to transmit and amplify sound vibrations.

The system consists of three elements:

Malleus. Includes the head (caput mallei), neck (collum mallei), handle (manubrium mallei), and processes (anterior and lateral — processus anterior et lateralis). Notably, the handle of the malleus is firmly attached to the tympanic membrane.
Incus. Consists of the body (corpus incudis), as well as short and long limbs (crus breve, crus longum). The long limb articulates directly with the stapes.
Stapes. Features a head (caput stapedis), a base or footplate (basis stapedis), and two limbs — anterior and posterior (crura stapedis). The base of the stapes is securely fixed in the vestibular window (fenestra vestibuli).

The ossicles are connected by two synovial joints: the incudomalleolar joint (articulatio incudomallearis) and the incudostapedial joint (articulatio incudostapedia).

Muscles of the Middle Ear

The movement of the ossicular chain and tension of the tympanic membrane are regulated by two specialized muscles:

Tensor tympani muscle (m. tensor tympani). As the name suggests, it is responsible for tensioning the tympanic membrane. It is innervated by branches of the trigeminal nerve (n. trigeminus).
Stapedius muscle (m. stapedius). Its function is to dampen excessive mobility of the stapes, protecting the inner ear from loud sounds. It is innervated by the facial nerve (n. facialis).

Pharyngotympanic Tube

The pharyngotympanic tube (tuba auditiva, also known as the auditory or Eustachian tube) is a canal approximately 3.5–4 cm long that anatomically connects the tympanic cavity to the nasopharynx.

Its structure comprises two parts:

Bony part (pars ossea);
Cartilaginous part (pars cartilaginea).

The main functions of the pharyngotympanic tube are continuous ventilation of the middle ear and equalization of pressure within the tympanic cavity relative to atmospheric pressure.

Mnemonic

To remember the order of the auditory ossicles from the tympanic membrane inward, use the acronym MIS: Malleus — Incus — Stapes.

Frequently asked questions

What openings does the pharyngotympanic tube have?

The pharyngotympanic tube has two openings that open into the nasopharynx and the tympanic cavity.

Pharyngeal opening of the pharyngotympanic tube (ostium pharyngeum tubae auditivae) — located on the lateral wall of the nasal part of the pharynx.
Tympanic opening of the pharyngotympanic tube (ostium tympanicum tubae auditivae) — located in the upper part of the anterior (carotid) wall of the tympanic cavity.

Which arteries supply blood to the tympanic cavity?

The walls and mucous membrane of the tympanic cavity are supplied by the following arteries:

Anterior tympanic artery (a. tympanica anterior) — a branch of the maxillary artery (a. maxillaris).
Caroticotympanic branch (r. caroticotympanicus) — arises from the internal carotid artery.
Superior tympanic artery (a. tympanica superior) — a branch of the middle meningeal artery.
Posterior tympanic artery (a. tympanica posterior) — a branch of the stylomastoid artery (a. stylomastoidea).
Inferior tympanic artery (a. tympanica inferior) — a branch of the ascending pharyngeal artery (a. pharyngea ascendens).

Which nerves form the tympanic plexus?

The tympanic plexus (plexus tympanicus) is formed by branches of the glossopharyngeal nerve.

The primary nerve contributing to this plexus is:

Tympanic nerve (n. tympanicus) — arises from the inferior ganglion of the glossopharyngeal nerve, enters the tympanic cavity, and forms the tympanic plexus (Jacobson's nerve).

What anatomical landmarks are found on the labyrinthine wall of the tympanic cavity?

The labyrinthine (medial) wall of the tympanic cavity features the following anatomical structures:

Promontory (promontorium) — a central bulge formed by the basal turn of the cochlea.
Vestibular window (fenestra vestibuli) — an oval window located above and behind the promontory, closed by the base of the stapes.
Cochlear window (fenestra cochleae) — a round window located inferior to the promontory, closed by the secondary tympanic membrane.
Pyramidal eminence — houses the stapedius muscle (m. stapedius).

Which ligaments anchor the auditory ossicles within the tympanic cavity?

The auditory ossicles are anchored in the tympanic cavity by a system of ligaments:

Anterior ligament of the malleus — connects the neck of the malleus to the angular spine of the sphenoid bone.
Lateral ligament of the malleus — extends from the head and neck to the margins of the tympanic notch.
Superior ligament of the malleus — connects the head to the roof of the tympanic cavity.
Posterior ligament of the incus — connects the posterior limb to the floor of the entrance to the mastoid antrum.
Superior ligament of the incus — suspends the body of the incus from the roof of the epitympanic recess.
Annular ligament — attaches the base of the stapes to the margins of the vestibular window.

Where is the tympanic cavity located?

The tympanic cavity is located inside the petrous part of the temporal bone.

What is the handle of the malleus fused with?

The handle of the malleus (manubrium mallei) is anatomically fused with the tympanic membrane.

Where is the base of the stapes fixed?

The base of the stapes (basis stapedis) is anchored in the vestibular window (fenestra vestibuli).

What are the functions of the pharyngotympanic tube?

The pharyngotympanic tube provides ventilation for the middle ear cavities and equalizes pressure between the tympanic cavity and the nasopharynx.

Go deeper

Topography of the tympanic cavity walls and their relation to adjacent blood vessels
Mechanics of the joints of the auditory ossicles
Clinical anatomy of the communication between the tympanic cavity and mastoid antrum
Detailed histological structure of the tympanic cavity mucosa
Innervation patterns of the middle ear muscles