Erratum in:

Laryngoscope. 2006 Nov;116(11):2098.

Orientation of the manubrium mallei: inexplicably widely variable.

Temporal Bone Laboratory, Emory University, 5455 Meridian Mark Road, Atlanta, GA 30342, USA. ntodd@emory.edu

BACKGROUND: There is no consensus why the manubrium of the malleus, as viewed clinically through the external ear canal, generally points downward and posteriorly. OBJECTIVES: To depict the alignment of the handle of the malleus, viewed clinically through the external auditory canal, relative to the zygomatic arch, the Frankfort plane, and a visual plane proxy and relative to the horizontal semicircular canal. Also, to assess bilateral symmetry and manubrium alignment relative to mastoid pneumatization. STUDY DESIGN: Postmortem anatomic dissection of 41 bequeathed adult crania without clinical otitis. METHODS: The line of the manubrium as viewed through the external ear canal was measured relative to the Frankfort plane, to a proxy of the visual plane, and to the zygomatic arch. Mastoid sizes were determined radiographically. In a subset of 10 crania additionally studied by computed tomography, the manubrium position was checked relative to the horizontal semicircular canal. RESULTS: Relative to the zygomatic arch and Frankfort and visual planes, the range of manubrium angles was at least 45 degrees. Bilateral symmetry was found, each r 0.38 or greater (P < .05). Relative to the horizontal canals, the range of manubrial angles was 30 degrees, with symmetry suggested. Alignment did not correlate with mastoid pneumatization. CONCLUSION: Manubrium orientation as viewed through the external auditory canal is not obviously explicable. The wide variety of manubrium orientations may explain the manubrium-stapes offset that perplexes manubrium-stapes surgical constructions.

PMID: 16148693 [PubMed - indexed for MEDLINE]