[TA] portion of spinal cord that consists of the five lumbar segments (L1-L5) and from which five pairs of lumbar spinal nerves originate; in the adult it is located in the T10-L1 portion of the vertebral canal, and is enlarged relative to other parts of the cord because of its involvement in innervation of the lower extremity. SYN: lumbar segments L1-L5 of spinal cord [TA], pars lumbalis medullae spinalis [TA], segmenta lumbalia L1-L5 [TA], segmenta lumbalia medullae spinalis.