Spinal Cord: a soft, gelatinous substance that is protected from injury by being encased in the bony “spinal column.” Shorter than the length of the spinal column. Approximately 45 centimeters in length with an average diameter of 1 to 1.5 centimeters. Begins at the "foramen magnum" of the “skull” and extends within the "vertebral canal" to terminate as the cone-shaped “conus medullaris.” (Patestas, 54)

A thick bundle of nerve fibers that conducts a steady stream of messages between brain and body. These messages include things like touch and pain (being transmitted) up from the skin, and motor commands (being transmitted) down to the muscles. (RamachandranTTB, 17) Consists of nerve cells and bundles of nerves connecting all parts of the body with the brain. (OxfordMed) Contains central “gray matter” and peripheral “white matter.” The gray matter contains many neuronal “cell bodies” and “synapses.” The white matter contains ascending and descending “neural pathways.” The ascending pathways relay sensory information to the brain. The descending pathways relay motor instructions down from the brain. (S.Goldberg, 19) Surrounded by “pia,” “arachnoid,” and “dura mater.” (Blumenfeld, 321) (These) “meninges” surround the entire spinal cord and, in turn, are enveloped by epidural fat. Affixed by about 21 pairs of ligaments to the dura mater. (Patestas, 54) Functions as a central relay station, receiving incoming information from the body and the brain. Functions as a central processing station, conveying outgoing information to the body and the brain. (Patestas, 54)

Conus Medullaris: the end of the spinal cord, at the level of the lower end of the first “lumbar vertebra.” (OxfordMed)

Dorsal Horn: crescent-shaped area of gray matter in the spinal cord. (OxfordMed)

Foramen Magnum: a large hole in the “occipital” bone through which the spinal cord passes. (OxfordMed)

Spinal Segment: the region of the spinal cord associated with a particular pair of spinal nerves. (Patestas, 57)

Ventral Horn: crescent-shaped area of gray matter in the spinal cord. (OxfordMed) Contains motor neurons that project anteriorly from either side of the center of the spinal cord. (NCIt) Also referred to as ‘ventral horn of the spinal cord.'