The spinal cord is tubular in shape and has 32 segments with the gray matter in the center and white matter on the outside. Each segment has nerve rootlets on the dorsal and ventral surfaces with a sensory ganglion attached to the dorsal nerve rootlets. These dorsal root ganglia contain the primary cell bodies of the general sensory systems—pain, temperature, touch, and pressure from the neck, thorax, abdomen, and extremities. The gray matter is shaped like a butterfly, and the gray matter in all levels has three zones: a dorsal horn, a ventral horn, and an intermediate zone. A lateral horn containing the preganglionic sympathetic neurons is found in levels T1–L2. The surrounding white matter is divided into three columns: dorsal, ventral, and anterior. The white matter is organized with the ascending systems on the outside and the descending systems closer to the gray matter. The corticospinal and corticobulbar descending motor pathways provide cortical control to these ventral horn cells.