下肢穴位传入纤维大部分经过腰

骶节段后根进入脊髓

足三阳经(足阳明胃经、足太阳膀胱经和足少阳胆经)在下肢的穴位主要位于下肢的外侧及背侧

其传入纤维主要由骶丛的分支由腰4至骶2节段后根进入脊髓

切断腰4至骶2节段的后根

可取消针刺“足三里”的效应

腰4至骶2节段后根纤维进入脊髓后在中枢投射的部位

能反映出足三阳经在下肢穴区传人纤维向中枢投射的范围

而腰4至骶2节段后根纤维在脊髓和延髓内的投射的研究资料很少

至于到延髓的一些核团如三叉神经脊束核、巨细胞网状孩和小细胞网状The afterent fibers of the points of three Yang Channels of the Foot in the lower limbs enter the spinal cord by L4-S2 dorsal roots. In order to research that the afferent fibers of the three Yang Channels of the Fo- ot in the lower 1imbs projected to the areas in the centre

the present experiment adopted excision of L4-S2 neighbouring two spinal ganglions in the cats. The sections were stained with the Fink-Heimer's silver impreg- naton methods modified by Janet. The distributions of dorsal root fibers in the spinal cord medulla oblongata were observed. The degenerative fibers of L4-S2 dorsal roots going into the spinal cord were distributed over most areas of the dorsal funiculus. There were a mo- derate or a large number of degenerative fibers in the Rexed Ⅲ-Ⅸ lamina of the ipsilateral gray matter. The degenerative fibers continued 2-3 segments for rostral and caudal orientation. The degenerative fibers in the nucleus dorsalis continued 6

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segments for rostral orientation. There were a few degenerative fibers in the Rexed Ⅷ-Ⅸ lamina of contralateral spinal cord. There were a large number of degenerative fibers in the middle region of the nuclei gracilisa

moderate number in the rostral region of the nuclei gracilis

a few in the contralateral rostral region of the nuclei gracilis

in the ipsilateral medial cuneate nucleus and lateral cuneate nucleus

in the caudal nucleus and middle nucleus of the spinal trigeminal tract on both sides

and in the nucleus reticularis giganocellularis and nucleus reticularis parvocellularis of the reticular formation on both sides. The results suggested that L4-S2 dorsal fibers projected to the Rexed V lamina of the spinal cord

the posterior column nuclei

the nucleus of the spinal trigeminal tract

the nucleus reticularis gigantocellularis and the nucleus reticuaris parvocellularis. Since the points of the three Yang Cha- nnels of the Foot in the lower 1imbs situated in the dorsal and lateral po- rtion of the lower limbs

the.afferent fibers entered the spinal cord by L4 -S2 dorsal root. Therefore the projection areas in the centre by L4-S2 do- rsal root fibers reflected the projection areas in the centre

into which the afferent fibers of the three Yang Channels of the Foot in the 10wer limbs projected. In order to study the mechanism of acupuncture activity on the points of the three Yang Channel of the Foot in the lower limbs and the theory concerning the relationship between the Channels and Zang-Fu organs

the results provided some morphological evidence.