目的　探讨恒河猴（活体）腰大肌对腰椎运动生物力学的关系。  方法　取恒河猴4只，动态X线片观察分别在正常状态下、切断一侧腰大肌、切断双侧腰大肌；分别做正、侧位数码照像。在正位DR照片上，进行椎体旋转级评价；在侧位DR照片上，腰曲运用应用数学几何学弓形面积计算法，计算出腰曲的弓形面积。利用统计学软件，分析恒河猴在正常状态下、一侧腰大肌切断后和两侧腰大肌切断后分别于坐位、站立位、跨步的椎体旋转角度和腰曲弓形面积。  结果　在坐位、站立位、跨步3种不同的状态下，相比于正常腰大肌正常状态，一侧腰大肌切断后，椎体旋转级数和腰曲的弓形面积测量都有显著性差异；而在双侧腰大肌切断后，椎体旋转级数和腰曲的弓形面积测量变化，相比于术前，并无显著差异。　结论　腰大肌是腰椎运动和维持腰曲的主要肌肉，在生物力学上，是维持腰椎力学平衡的前方二维动力。

Objective　To explore the function of psoas major muscles on lumbar spine movements in biomechanics of Rhesus.　 Methods　Four Rhesus were studied in our study. The dynamic AP and lateral digital X-ray views of Rhesus were conducted in three different status, including normal status, one side psoas major resection and bilateral psoas major resection. Vertebral rotations of the spine were evaluated in AP views. The segment areas of lumbar curvatures were calculated in lateral views in applied mathematics geometry. The parameters of vertebral rotational degrees and segment areas of lumbar curvatures were analyzed in three different positions: sitting, standing and stepping in statistics.　Results　For measurements of both the vertebral rotational degrees and segment areas of lumbar curvatures, there were significant differences between normal status and one side psoas major resection, but there were no significant differences between normal status and bilateral psoas major resection.　Conclusions　Psoas majors are the major muscles to maintain lumbar curvature and conduct vertebral movements. In statistics, these particular muscles are the anterior powers to maintain the lumbar spine balance.