胸腰部末梢神経の三次元構造

Three Dimensional Structure of the Spinal Nerves in the Thoracolumbar Body Trunk

要旨：胸神経と腰神経の三次元構造をSihler染色を施したラット標本で調べた．背側枝と腹側枝の外側枝は脊髄神経の基点（椎間孔部）より約1～2分節，腹側枝の前枝は約7分節，それぞれ尾側の点で体表筋を貫通して皮下に現れていた．皮下結合組織の中を背側枝皮枝は2～3分節，外側枝皮枝では2～4分節，尾側に向かっていた．体幹横断線と神経のなす角度は尾側分節ほど増大し，特に腹側枝で増加が顕著であった．今回明らかになった脊髄神経各枝の三次元構造と，すでに報告した皮節図と骨節図を総合すると，脊髄神経の支配領域は脊髄神経の起点を頂点とし尾側方向に広がる「変形した円錐面様」の形状をしていることが判明した．この三次元構造は脊椎脊髄疾患の診断と治療において新たな観点を提供すると思われた．

Abstract : The three-dimensional structure of thoracic and lumbar nerves was investigated in rats using Sihler's staining method. It was observed that the dorsal and lateral cutaneous nerves pierced the surface muscles to enter the subcutaneous tissue at a point 1-2 segments caudal to the base of the spinal nerve, while the ventral cutaneous nerves pierced the surface muscles 7 segments caudal to the base. The dorsal and lateral cutaneous nerves also ran more caudally, 2-3 and 2-4 segments, respectively, in the subcutaneous tissue. In addition, the tilt angles of spinal nerve rami lying against the transverse plane of the body trunk increased caudally, and the ventral rami showed a drastic increase in their tilt angle. Combined with our previous studies on dermatomes and sclerotomes, the present results imply that the innervation territory of the spinal nerve is shaped like a“deformed cone”, with the apex at the base of the spinal nerve and the lateral aspect expanding caudally. The stereoscopic structure of spinal nerve innervation territories may provide novel viewpoints for use in the diagnosis and treatment of disorders of the spine and spinal cord.