THE FUSTIS OF MIDDLE EAR

Background: The fustis is the largest bony trabecula of the middle ear, traversing from the basal turn of the cochlea to the styloid complex within the fundus of the round window chamber and subtympanic sinus.Its anatomical variability, structural features,and clinical surgical importance are underappreciated in otologic literature.

Objective:To review the structural and functional anatomy of the fustis,highlight its variability,typology,and delineate its critical surgical significance in otological procedures.

Methods: A synthesis of available anatomical and clinical literature, combined with detailed morphologic characterization, was undertaken to describe the role of the fustis in normal and pathological middle ear states.

Results:The fustis,variably present and developed, is a smooth, oblique bony bar marking the boundary between the round window chamber and the sub cochlear tunnel. It provides structural support, anatomical guidance, and contributes to the resonance and ventilation mechanisms of the round window niche. Surgically, it serves as a key landmark for safe navigation and approach to the round window, and its preservation is crucial given its resistance to cholesteatoma and neo-osteogenesis risk upon drilling.

Conclusion: The fustis is a reliable anatomical marker and functional buttress in the middle ear, aiding surgical orientation and improving operative outcomes. Its respect in otologic surgery is paramount due to its unique anatomical and physiological properties [1][3][5