Etlmaoidal roof was studied on 110 cadaveric head specimens. It is a bone plate of 28.2 nun long, 0.88 nun thick, 7.5 nma wide at the anterior edge and 9.6 mm wide at the posterior edge. The bone plate declines intero-posteriorly. The connecting types of the etlunoid roof with cribriform are horizontal (17.3%) and high plate form (82.7%). The anterior and posterior etlunoid arteries penetrate below the ethmoidal roof at the same level of cribriorfonn in etlunoid silms. The method lbr recognizing the etlunoidal roof in endoscopic nasal sinus surgeries was discussed. An antomical classification of the anterior ethmoid sinus and its clinical significance (p 84) Sixty adult cadaveric head specimens (34 male and 26 felnale) were shldied with special attention on the pnetunatization of the anterior etlmaoid sinus. The anterior ethlnoid sinus was divided into intraetlmmid t?qae (70.83%) and extraetlunoid type (29.17%), the latter was subdivided into:superorbit (17.5%), inferorbit (7.5%) and mixed (4.17%) type, according to the pattern of their extending over extraetlunoid. This classification can very well depict the syntopic relationship of the anterior etlmmidal sinus with the orbit, the frontal sinus and the maxillary sinus. The dimension , wall thickness, sinus ostia and pnetmlatization of the anterior etlunoid sinus were observed on 60 adult head specimens (34 male and 26 female). According to the cell ostia position, the cells of anterior etlunoid sinus were divided into four groups as frontal recess cell (in 88.3%),etlunoid bulla cell (100%),ixffundibulmn cell (85.8%) and maxillary sinus cell (3.3%). Clinical points relating to anterior etlunoidal surgery were discussed. Clinical anatomy of the extranasal ethmoidectomy (p 88) The anatomical structures on the medial orbital wall were measured on 60 adult head specimens (34 male and 26 female). The distances from Dacryon point to the anterior and posterior etlunoidal foramens and optic foranaen were 19, 32 and 40 nun respectively. The distances from the posterior ethlnoidal foralnen to the (contd. page 178) Surg Radiol Anat (1994) 16:178 Chinese Journal of Clinical Anatomy Abstracts vol 14, issue 2, 1996 Original articles anterior ethmoidal foramen and optic foralnen were 14 and 9 nml separately. 70% of the anterior etlunoidal