[TA] one of 31 portions of the spinal cord, each of which gives rise to the anterior and posterior roots that combine to form a single pair of spinal nerves. These are the cervical spinal cord segments [C1-C8]; the thoracic spinal cord segments [T1-T12]; the lumbar spinal cord segments [L1-L5]; the sacral spinal cord segments [S1-S5], and the coccygeal spinal cord segment [Co]. SYN: segmenta medullae spinalis C1-Co [TA].