part of part of extends_fibers_into neuron projection bundle nervous system central nervous system nerve nerve root A continuation of the neuron projection bundle component of a nerve inside, crossing or immediately outside the central nervous system. FMA has 'central zone of nerve' which is the superclass of cranial nerve tracts, which the FMA sometimes calls roots initial segment of nerve UBERON:0002211 We consider cranial nerve roots to be primarily CNS structures, but model spinal nerve roots as PNS structures, due to the existence of ganglia on the roots. FMA:82524 UMLS:C0228084 The continuation of the neurite bundle and associated glia of a nerve, inside the central nervous system[FBbt:00007602, FBC:DOS]. radix nervi uberon FMA:5981