what are its divisions?
Six to eight motor nerve rootlets branch out of right and left ventro lateral sulci in a very orderly manner.
Spinal cord
Six to eight motor nerve rootlets branch out of right and left ventro lateral sulci in a very orderly manner. 
what part of the brain controls cranial nerves Central nervous system how are these nerves named? With Roman numerals I–XII what is the system you mentioned above? It is the part of the nervous system consisting primarily of the brain and spinal cord. can you explain this cord? The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column.
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Spinal cord [SEP] Spinal cord segments
The human spinal cord is divided into segments where pairs of spinal nerves (mixed; sensory and motor) form. Six to eight motor nerve rootlets branch out of right and left ventro lateral sulci in a very orderly manner. Nerve rootlets combine to form nerve roots. Likewise, sensory nerve rootlets form off right and left dorsal lateral sulci and form sensory nerve roots. The ventral (motor) and dorsal (sensory) roots combine to form spinal nerves (mixed; motor and sensory), one on each side of the spinal cord. Spinal nerves, with the exception of C1 and C2, form inside the intervertebral foramen (IVF).