RESUMO
We studied the intradural variations of spinal nerve rootlets in 100 cases of Korean adults. The results of the study are as follows ; 1. The incidence of intrasegmental variations (abberrant rootlets) is high in cervical segments and decreased toward lumbosacral segments. The incidence is higher in posterior rootlets than anterior, except cervical sesments. 2. The incidence of intersegmental variations is higher in posterior rootlets than anterior, and generally high in cervical and lumbar segments. 3. We divide the intersegmental variations into supernumerary rootlets, dividing rootlets, and anastomosing rootlets, and among them the incidence of anastomosing rootlets is higher. We divide the anastomosing rootlets into parallel anastomosing rootlets, uniting anastomosing rootlets, and rearrangement anastomosing rootlets. 4. The anterior to posterior anastomosing of spinal nerve rootlet is present in 4 of cases studied.