寰椎侧块结节及枢椎齿突的解剖学形态观测及临床意义

Quantitative anatomy of the tubercle of lateral mass of atlas and dens of axis and its clinical significance

目的：研究寰椎侧块结节和枢椎齿突的形态学特征.方法：对200例寰椎侧块结节和200例枢椎齿突的解剖学形态进行观察及分类测量.测量寰椎侧块结节的长轴、短轴、结节到下关节面的距离和结节间距以及齿突的轴线与枢椎椎体垂线间的夹角.结果：寰椎侧块结节存在多种分型,其中双侧均为结节52.5％,双侧均为结节关节面32.0％,左结节右关节面6.0％,左关节面右结节9.5％其高度为（0.156±0.087） cm.枢椎齿突左侧面为结节状突起45.5％,关节面状13.5％,光滑无磨损41.0％;右侧面为结节状突起50.0％,关节面状12.5％,光滑无磨损37.5％.齿突偏斜角的范围为-7.46°（向左偏斜）到4.74°（向右偏斜）.结论：寰椎侧块结节存在着结节与结节关节面2种主要的分型,且各自有多种形态特征,其形态特征可能与结节间距及齿突偏移有关.

Objective： The gross anatomic features of the atlas （C1） and axis （C2） have been reported, but morphologic study of the tubercle of C1 lateral mass and C2 dens, particularly the combination of both, remains little understood. The study was undertaken to provide original observations and measurements of the C1 lateral mass and the C2 dens. Materials and Methods ： Observations, classifications and direct measurements using digital calipers and MB-Ruler were taken from 200 dry atlas and axis vertebrae. The length, width and height of the tubercle of C1 lateral mass were measured. The offset angle of C2 dens, which is the angle between the axis of C2 dens and axis of C2 vertebra, was measured by MB-Ruler. The distance between the tubercles and the width of the dens was also evaluated. Results： We found that the tubercles of C1 lateral mass could be divided into various types, namely, the two tubercle-shaped sides （52.5 M）, the two articular facet- shaped sides （ 32.0 %）, left-tubercle-right-articular facet （ 6.0 %） and left-articular facet-right-tubercle （ 9.5 %）. The mean height was 1.56± 0.87 mm. In the C2 vertebrae, the facets of dens could be classified as nodular-shaped, articular facet-shaped and smooth facet. The offset angle varied within a range from --7.46° （dens deviates left） to 4.74°（dens deviates right）. Conclusion： This study indicates that the tubercle of C1 lateral mass have two main types： tubercle and tuberculous articular facet for the first time in Chinese population. Its morphometric characteristics may be related to the distance between the tubercles and the offset angle of C2 dens. This anatomic fact may held in planning surgical approaches.