Three-dimensional anatomy of the human endolymphatic sac.

Computerized and graphic three-dimensional reconstruction of a human endolymphatic duct and sac (ES) showed the ES to be a fusiform and flattened structure with marked tubularity, especially in the extraosseous region. The specimen was 18.2 mm long. It measured 60 X 200 microns at the isthmus portion of the endolymphatic duct and 200 X 7000 microns at the broadest part of the ES. The volume of the endolymphatic duct was 0.03 mm3 and of the ES, 1.85 mm3. The extraosseous ES volume represented more than two thirds of the total ES volume.