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Vestibule

The vestibule is a central, oval-shaped cavity situated within the bony labyrinth of the inner ear, positioned between the cochlea anteriorly and the semicircular canals posteriorly. It serves as a critical component of the vestibular system, playing a pivotal role in balance and spatial orientation. The vestibule houses two important membranous sacs—the utricle and saccule—which are responsible for detecting linear accelerations and head positions relative to gravity. In radiological imaging, the vestibule’s unique location and structure make it a key landmark for assessment of inner ear pathology, trauma, and congenital abnormalities.

Synonyms:

  • Vestibular cavity

  • Central cavity of bony labyrinth

  • Vestibular space

Function:

  • Acts as the central chamber of the bony labyrinth, connecting the cochlea and semicircular canals

  • Contains the utricle and saccule, which detect linear acceleration and gravitational forces

  • Transmits sound vibrations from the stapes footplate to the cochlea via the oval window

  • Plays an essential role in maintaining balance and equilibrium

  • Serves as a conduit for endolymph and perilymph fluid between cochlea and semicircular canals

MRI Appearance:

  • 3D T2-Weighted Imaging:

    • Vestibule appears as a well-defined, high signal intensity (bright) structure within the petrous temporal bone

    • Clearly demarcated from the adjacent low-signal intensity bone

    • The contents (utricle and saccule) may not be individually distinguished unless pathology or high resolution is used

    • Helps in assessing fluid content and detecting membranous labyrinth disorders (e.g., labyrinthitis, vestibular schwannoma)

  • T1-Weighted Imaging:

    • Vestibule shows low to intermediate signal intensity (relatively dark)

    • Less conspicuous compared to T2-weighted images

    • May enhance following contrast administration if there is inflammation, infection, or neoplasm involving the vestibule

CT Appearance:

  • Vestibule appears as a small, rounded or ovoid lucency (dark area) within the dense petrous part of the temporal bone

  • Bony margins are sharply outlined

  • Communicates anteriorly with the basal turn of the cochlea and posteriorly with the semicircular canals

  • The stapes footplate and oval window are visualized at the lateral aspect of the vestibule

  • High-resolution temporal bone CT is ideal for assessing bony anatomy, congenital abnormalities, fractures, and otosclerosis involving the vestibule

MRI images

Vestibule MRI 3T axial image

MRI images

Vestibule MRI 3T sagittal image