3-DIMENSIONAL RECONSTRUCTION AND MEASUREMENT STUDY OF HUMAN EUSTACHIAN-TUBE STRUCTURES - A HYPOTHESIS OF EUSTACHIAN-TUBE FUNCTION

Histologic sections from nine temporal bones with eustachian tubes (ET s) attached were analyzed with a computer-aided three dimensional reco nstruction method to determine the curvature and tilt of the ET and th e anatomic relationships between the medial lamina of the ET cartilage , the levator veli palatini muscle (LVPM), and Rosenmuller's fossa. It was found that the ET is convex superomedially and is tilted medially . The LVPM is located inferolateral to the inferior margin of the medi al lamina of the anterior ET cartilage. The LVPM is inferior to the me dial lamina of the posterior ET cartilage. These findings suggest that the LVPM opens the anterior cartilaginous portion of the ET by rotati ng the medial lamina with increased dimension of the muscle body when it contracts. Rosenmuller's fossa extends along the ET with rich lymph oid tissues as far as approximately one half the total length of the E T and very close to the skull base.