OBJECTIVESTo explore shape and position relationship of the structures with in sinus triangle region, and provide the anatomic foundation for extended presigmoid operative approach.

METHODSTen cadaveric heads and 15 skull-base specimens fixed with 10% formalin, with aid of operative microscope, the shape and relations of structures with in the sinus triangle region were observed and microphotographed. Four cadaveric heads were sectioned in different plane using collodion embedding process.

RESULTSJugular blub (JB) had high -placed jugular blub (HJB), normal jugular blub (NJB) and low-placed jugular blub (LJB). The incidence of HJB was 8% and 18% for the left and right sides (P < 0.01). The JB dome can extend upward the hypotympanic cavity and the posterior wall of the internal acoustic meatus. The incidence of NJB and LJB was 36% and 30%, and 6% and 2% respectively. The level distance between the posterior semicircular canal and petrosal posterior surface was (4.1 +/- 1.1) mm. The distance between the JB and vertical part of the facial nerve was (3.2 +/- 0.5) mm and (2.0 +/- 0.4) mm. The distance between the JB and posterior margin of the internal acoustic port was (7.5 +/- 1.7) mm and (4.0 +/- 1.0) mm.

CONCLUSIONSKnowing the shape and position relationship of structures in the sinus triangle region is favorable for preserving the important structures in extended presigmoid operative approach.