不同张力对家兔正中神经形态的影响

EFFECTS OF THE DIFFERENT TENSIONS ON THE MORPHOLOGIC FEATURE OF THE MEDIAN NERVE IN THE RABBIT

采用弦式加载，造成对家兔正中神经的单纯性牵拉，并对神经在单纯性牵张力作用下的形态变化和导致神经急性牵拉伤的临界张力值进行了研究。结果表明：当施加到非游离正中神经上的总应力为２３ｇ·（ｍｍ２）－１时，内部神经纤维的延长达到生理极限；当总应力升至６１ｇ·（ｍｍ２）－１时，内部神经纤维发生损伤。对游离的正中神经，当神经干承受的应力为１３ｇ·（ｍｍ２）－１时，内部神经纤维的延长达到生理极限；当应力升至２３ｇ·（ｍｍ２）－１时，神经纤维出现损伤；应力升至１８２ｇ·（ｍｍ２）－１后，神经干中心区的神经纤维发生断裂。组织学观察显示：当牵张力施加到正中神经上，神经内最易损伤的成分是髓鞘；神经纤维最先断裂的部位是Ｒａｎｖｉｅｒ结；在横切片上，组织损伤最严重的区域位于神经干的中心。本文讨论了受牵拉的神经形态变化和确立损伤临界张力的临床意义。

The simple stretching was applied on the median nerves in the rabbits by using string-type loading,and both the nerve morphologic changes under the action of the different tensions and the critical tension values which led to the acute stretch injury of the median nerve was studied.The result demonstrated:when the total stress loading on the non-free median nerve was at 23g(mm2)-1 ,the elongation of the internal nerve fibers reached the physiological limit;and the damage of the internal nerve fibers occurred when the total stress increased to 61g.(mm2)-1.For the free median nerve,when the stress of nerve trunk bearing was at 13g.(mm2)-1,the elongation of the internal nerve fibers reached the physiological limit;when the stress increased to 23g.(mm2)-1,the damage of the nerve fibers took place;and after the stress ascended to 182g.(mm2)-1,the nerve fibers ruptured in the center of the nerve trunk.Histological evidence showed that when the stretching tension loading on the median nerve,the most easily injured component was myelin,the firstly breaking region of a nerve fiber was at Ranvier node,and on a transverse section,the most seriously damaged area was in the center of the nerve trunk.The clinical significance both of the morphologic change of stretched nerve and the determination of the critical tension was discussed.