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Infraglottic cavity

The infraglottic cavity is an important anatomical region of the larynx, located below the vocal cords and extending to the lower border of the cricoid cartilage. This area serves as a conduit for air passage between the glottis and the trachea and is clinically significant in the evaluation of subglottic pathology, airway compromise, and laryngeal tumors. Radiological assessment—particularly with MRI and CT—plays a crucial role in delineating its boundaries, evaluating lesions, and guiding management.

Anatomy of the Infraglottic Cavity

  • The infraglottic cavity lies below the glottis (true vocal cords) and extends to the inferior border of the cricoid cartilage.

  • Bounded superiorly by the lower surface of the vocal folds.

  • Inferior limit is the lower border of the cricoid cartilage, where it becomes continuous with the trachea.

  • Laterally bordered by the conus elasticus and the inner surface of the cricoid cartilage.

  • Anteriorly and posteriorly, it is also related to the cricoid cartilage.

  • Lined by respiratory epithelium (ciliated pseudostratified columnar).

MRI Appearance of Infraglottic Cavity

  • T1-Weighted Images

    • The mucosa and submucosa show intermediate to low signal intensity.

    • Cricoid cartilage may appear as low signal due to its dense cartilaginous nature.

    • Fat within the surrounding tissue appears as high signal.

  • T2-Weighted Images

    • Mucosa and submucosa typically display high signal intensity.

    • Cartilage remains low to intermediate signal.

    • Edema, inflammation, or tumor may increase signal intensity in the soft tissues.

  • STIR (Short Tau Inversion Recovery)

    • Suppression of fat signal makes fat-containing tissues appear hypointense (dark).

    • Pathologic tissues such as edema, tumor, or inflammation are bright (hyperintense) due to increased free water content.

    • Useful for detecting subtle infiltration or edema in the infraglottic region.

CT Appearance of Infraglottic Cavity

  • The infraglottic cavity appears as an air-filled column below the glottis.

  • Bony and cartilaginous structures, such as the cricoid, are well visualized.

  • Normal mucosa appears as a thin, symmetric soft tissue density lining the airway.

MRI images

Infraglottic cavity MRI axial image