Definition

The vestibule is the central part of the osseous labyrinth, and is situated medial to the tympanic cavity, behind the cochlea, and in front of the semicircular canals.

The etymology comes from the Latin vestibulum, literally an entrance hall.

Anatomical characteristics

It is somewhat ovoid in shape, but flattened transversely; it measures about 5 mm from before backward, the same from above downward, and about 3 mm across.

In its lateral or tympanic wall is the oval window

Oval window

The oval window is a membrane-covered opening which leads from the middle ear to the vestibule of the inner ear.Vibrations that come into contact with the tympanic membrane travel through the three ossicles and into the inner ear...

 (fenestra vestibuli), closed, in the fresh state, by the base of the stapes and annular ligament

Annular stapedial ligament

The Annular stapedial ligament is a ring of fibrous tissue that connects the base of the stapes to the oval window of the inner ear....

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On its medial wall, at the forepart, is a small circular depression, the recessus sphæricus, which is perforated, at its anterior and inferior part, by several minute holes (macula cribrosa media) for the passage of filaments of the acoustic nerve to the saccule; and behind this depression is an oblique ridge, the crista vestibuli, the anterior end of which is named the pyramid of the vestibule.

This ridge bifurcates below to enclose a small depression, the fossa cochlearis, which is perforated by a number of holes for the passage of filaments of the acoustic nerve which supply the vestibular end of the ductus cochlearis.

As the hinder part of the medial wall is the orifice of the aquæductus vestibuli, which extends to the posterior surface of the petrous portion of the temporal bone

Temporal bone

The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...

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It transmits a small vein, and contains a tubular prolongation of the membranous labyrinth, the ductus endolymphaticus, which ends in a cul-de-sac between the layers of the dura mater within the cranial cavity.

On the upper wall or roof is a transversely oval depression, the recessus ellipticus, separated from the recessus sphæricus by the crista vestibuli already mentioned.

The pyramid and adjoining part of the recessus ellipticus are perforated by a number of holes (macula cribosa superior).

The apertures in the pyramid transmit the nerves to the utricle; those in the recessus ellipticus are the nerves to the ampullæ of the superior and lateral semicircular ducts.

Behind, the five orifices of the semicircular canals can be found.

There is, in the frontal view, an elliptical opening, which communicates with the scala vestibuli of the cochlea.