Synonyms
Medical: Substantia alba spinalis CNS, spinal cord, brain, nerve cell, gray matter spinal cord
Spinal cord in general
Like the brain, the spinal cord belongs to the central nervous system (CNS) and runs in the spinal column, more precisely in the spinal canal. The spinal cord is connected at the top to a part of the brain, the medulla oblongata (elongated medulla), which leaves the skull through a bony hole, the so-called foramen magnum. The spinal cord runs protected in the spinal canal, which is formed by the vertebral bodies stacked on top of each other.
The spinal cord runs here up to about the level of the first or second lumbar vertebral body. Towards the bottom, the spinal cord tapers off in the so-called conus medullaris (medullary cone). This ends in the filum terminale, many thin connective tissue fibers. Below the second lumbar vertebral body, nerve fibers of the lower spinal nerves are then found, which are called cauda equina (horse’s tail) based on their morphology.
White matter of the spinal cord
The white matter of the spinal cord consists of the predominantly myelinated (i.e., isolated by a fat sheath) ascending and descending nerve fibers. These are bundled together as different strands (funiculi), each of which is further subdivided into tractus or fasciculi (= “small bundles”) with different functions. The cell bodies (perikaryes) of the nerve cell are located either in the brain or in the spinal cord: If they are located in the brain, the tract is called descending (efferent) because the information flows from the brain to the spinal cord.
If they are located in the spinal cord, the path is called ascending (afferent) because the information flows from the spinal cord to the brain. Some of the ascending and descending fibers, however, are fibers that belong to the spinal cord’s own apparatus; they are called basic bundles (Fasciculi proprii = “own bundles”). They are directly attached to the gray matter and conduct information within the spinal cord. Roughly speaking, there is a distinction on each side of the spinal cord between
- Anterior strand (Funiculus anteriorventralis)
- Lateral strand (Funiculus dorsalislateralis)
- Posterior strand (funiculus posterior or “medial lemniscus system”)
