Elevations in the wall of the developing neural tube that divide the developing spinal cord (neuromere) into portions to which dorsal and ventral roots are attached, or that divide the developing rhombencephalon (rhombomeres) into portions associated primarily with motor portions of the cranial nerves of the medulla and pons. SYN: encephalomere, neural segment, neurotome (2). [neuro- + G. meros, part]