ABSTRACT
The dorsal horns are well delineated. They reach posteriorly almost the dorsal limit of the spinal cord from which they are separated by a thin band of white matter, the marginal zone of Lissauer. The spinal cord is a cylindrical mass of nervous tissue that occupies the greatest part of the spinal canal, extending from the foramen magnum to end at the first to third lumbar vertebra. The spinal cord is covered with three membranes, or meninges, which contain a liquid, the cerebrospinal fluid. These meninges are pia mater, arachnoid and dura mater. The descending tracts of the spinal cord convey impulses for somatic movements, muscle tone, segmental reflexes, and visceral innervation. The spinal cord is a continuous unsegmented structure. The spinal cord presents several longitudinal furrows throughout its entire length. The ascending fibers of the spinal cord are organized into several fasciculi, mainly located in the funiculus posterior and the funiculus lateralis.
