Ultrastructure of Human Spinal Nerve Roots

Abstract

Motor and sensorial nerve roots are independent structures originating from 8 to 10 sensorial nerve rootlets that emerge from the posterolateral region of the spinal cord and from 6 to 8 motor rootlets located anterolateral to the spinal cord. The number of rootlets may increase in roots present at the level of the brachial plexus. The number of rootlets decreases to two to three at the sacral level and to one at the coccygeal level, giving shape to single nerve roots. Rootlet size varies, with the anterior rootlets being finer than the posterior ones. The diameter of nerve roots ranges between 0.7 and 0.3 mm. Compared with the diameter of an anterior rootlet, that of a posterior rootlet is approximately 1.5 times larger in the thoracic region, three times larger at the lumbar level, and three times larger in the cervical region.