Abstract: The stereoscopic orientation of the cervical zygapophyseal joint and the stability triangle of the motion segment were measured on 45 sets(male 25,female 20)of adult dry skeletons unearthed from Tongliao district in Inner M ongolia A utonomous Region. The coronal and sagittal angles of the cervical zygapophyslal joint decrease successively while the horizontal angle of that increases progressively fromC2-3toC6-7segment. The stability triangle of the motion segment is an isosceles tri-angle, in which the vertex angle is obtuse, and its gravity center lies posteriorly. therefore, the anterio--posterior stability of the cervical spine is less than the transverse ones.

Key words: Cervical zygapophyseal joint