ventral root of spinal nerve ventral root of spinal nerve in anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root is the efferent motor root of a spinal nerve. ventral root of spinal nervethe formation of the spinal nerve from the dorsal and ventral rootsdetailsidentifierslatinradix anterior nervi spinalista98a14.2.00.029ta26145fma5979anatomical terminology at its distal end, the ventral root joins with the dorsal root to form a mixed spinal nerve. additional images cervical vertebra medulla spinalis a spinal nerve with its anterior and posterior. the motor tract. diagrammatic transverse section of the medulla spinalis and its membranes. a portion of the spinal cord, showing its right lateral surface. the dura is opened and arranged to show the nerve roots. scheme showing structure of a typical spinal nerve.