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Tympanic part of temporal bone

The tympanic part of the temporal bone is a curved, thin plate forming the anterior and inferior walls of the external acoustic meatus (ear canal) and contributing to the tympanic ring. It plays a crucial role in separating the external acoustic meatus from the temporomandibular joint and is an important landmark in head and neck imaging.

Synonyms

  • Tympanic plate

  • Tympanic bone

  • Pars tympanica ossis temporalis

Anatomy

  • Forms the anterior, inferior, and part of the posterior wall of the external auditory canal

  • Lies below the squamous part and in front of the mastoid part of the temporal bone

  • Connects medially to the petrous part of the temporal bone

  • Its free edge forms the tympanic ring, which supports the tympanic membrane (eardrum)

  • Posteriorly, continuous with the mastoid part; anteriorly, related to the temporomandibular joint (TMJ)

MRI Appearance

  • Proton Density (PD):

    • Appears as a low signal intensity structure due to its cortical bone composition

    • Clearly outlines the external acoustic meatus, providing anatomical definition

  • Short Tau Inversion Recovery (STIR):

    • Markedly low signal (black) on STIR sequences because cortical bone lacks mobile protons

    • Useful for distinguishing bone from soft tissue or marrow pathology

  • T1-Weighted Images:

    • Very low signal (dark/black) representing compact bone

    • Thin, sharply defined curved rim outlining the ear canal

    • Helps differentiate the tympanic part from surrounding soft tissue structures

MRI images

Tympanic part of temporal bone mri