羊和人颏部受钝物撞击时动载变化特征及颞颌关节的缓冲作用

Characteristics of Dynamic Loading and the Cushioning Effect of Tempormadibular Joints during Impact on Chins in Goat and Man.

目的研究钝物撞击下颏时，下颌骨—颞下颌关节—颅骨复合体动载荷的变化特征。方法１２具羊头颅随机分为两组，进行交叉对照实验；第一组先以ｖ１＝１．１ｍ／ｓ速度撞击３次，然后ｖ２＝１．６ｍ／ｓ速度撞击３次；第二组的实验顺序则相反。２具人头颅先后分别以ｖ１，ｖ２被撞击３次。所有实验均由同一撞击物沿下颏至两颞颌关节连线的垂直方向撞击。结果在本实验条件下，（１）羊头颅交叉撞击实验表明，重复撞击对实验结果无影响（Ｐ＞０．０５）。（２）人头颅ｖ１撞击时间ｔ（４４．１４±３．３３ｍｓ）大于ｖ２（３９．２３±１．６０ｍｓ），但无显著差异（Ｐ＞０．０５）；但ｖ１撞击力ＦＰ（１６９．２０±２３．５８Ｎ）和撞击力ＦＳ（１０５．３７±２０．９６Ｎ）均显著小于ｖ２（３１９．４２±３５．７Ｎ，１５５．６７±２５．６７Ｎ）（Ｐ＜０．０１）。（３）若撞击速度相同，人头颅ｔ显著大于羊头颅（Ｐ＜０．０１），但是ＦＰ小于羊头颅（Ｐ＜０．０１）；二者撞击力变化曲线明显不同。结论（１）实验获得人下颏受钝物撞击的动载荷。（２）人类的颞颌关节的解剖结构使其能较好地缓冲外界冲击。（３）对于同一撞击对象，当撞击速度增加时，撞击持续时间减小。

Objective To investigate the dynamic load characteristics of mandibletempormadibular joints (TMJ)skull during blunt impact on the chin. Method Twelve goat heads were randomly divided into two groups,and were employed in a crosscontrol trial.Group 1 was first impacted by a blunt mass with a velocity (v1=1.1 ms) for three times,and then with another velocity (v2=1.6 m/s) for three times;group 2 was impacted with v2 and then v1 for similar times too.Two fresh human heads were experimented in the same way as goat heads in group 1.The same impact mass was used in all the experiments.The impact was exerted along the chin and vertically to the junctional line of both sides of TMJs. Result (1)The crosscontrol trial of goat heads showed that repeated impact didn't make any difference ( P >0.05) in the results of our experiment.(2)The impact time ( t ) in v1 of human heads (44.143.33 ms) was longer than that of v2 (39.231.60 ms) but without any statistical difference ( P >0.05),while the peak values of impact forces (FP) and slide forces of v1 (169.2023.58 N,105.3720.96 N) were both significantly lower than those in v2 (319.4235.7 N,155.6725.67 N)(XP <0.01).(3)With the same impact velocities,the human groups had longer t ( P <0.01),but lower FP ( P <0.01) as compared with the goat heads;furthermore,their forcetime curves were different. Conclusion (1)The dynamic load curves of human heads during impact on chins were obtained.(2)The anatomy structure of human TMJs enable it to well cushion the impact forces.(3)The impact forces rise significantly with the increase of impact velocity with which the impact time decrease.