Spinal Cord Cross Section

The Spinal Cord Main Functions: Transmission of neural signals between brain and rest of body Contains neural circuits that can independently control reflexes

Grey Matter The darker tissue of the brain and spinal cord Consists mainly of nerve cell bodies and branching dendrites Includes regions of the brain involved in muscle control, emotions, speech, decision making, and self-control 95% of all the oxygen that goes into the brain goes into the grey matter

White Matter The paler tissue of the brain & spinal cord, consisting mainly of nerve fibers with their myelin sheath CNS No dendrites (unlink grey matter) Transmits signals from one region of the cerebrum to another The “wiring” of the spinal cord; carries information Computer Analogy: Grey matter = the actual computer White matter = network cables connecting the computers together

Central Canal AKA “ependymal canal” Cerebrospinal fluid-filled space that runs up and down the length of the entire spinal cord Continuous with the ventricular system of the brain Represents the remainder of the central cavity of the neural tube (the embryo’s precursor to the CNS) Eventually closes off with age

Spinal Nerve There are main bundles of fibers that branch off the spinal cord and goes to other areas of the body Carries signals of sensation A pair of these spinal nerves branch out from each level of the spinal cord

Dorsal & Ventral Roots At the innermost base of each spinal nerve root there are 2 sub-roots that connect the nerve to white and grey matter: The dorsal nerve root: receives sensory (or touch) signals and carries them to the brain (afferent) Ventral nerve root: ventral root sends out signals of movement from the brain to the body (efferent)

Important Info About The Dorsal Nerve Root Controls pain and temperature sensations If severed, pinched, or constricted, the signals of dorsal nerve root will be intensified or interrupted Can cause: Pain Numbness Feeling of “pins and needles” Sensation of heat along nerve Possible causes of dorsal nerve root compression: Trauma Degenerative disc diseases Herniated Disc Bulging Disc

Ganglion Nerve Cell Cluster Located in the PNS (outside the brain/spinal cord) Involved in transmission of sensory information

Pia Mater The delicate innermost membrane of the meninges, enveloping the brain and spinal cord Thin fibrous tissue Impermeable to fluid Allows the enclosure of cerebrospinal fluid Helps to protect and cushion the brain When pia mater becomes inflamed, result = meningitis

Arachnoid Membrane One of the 3 meninges that helps protect the brain & spinal cord The “middle” meninges Tiny fibers extend of the Arachnoid membrane and attach to pia mater Resembles spider web (hence it’s name) Because the brain produces more cerebrospinal fluid (CFS) than the body uses each day, the discarded CFS escapes the subarachnoid space through the arachnoid granulations (tiny protrusions of the arachnoid mater)

Dura Mater Outermost membrane enveloping the brain & spinal cord Thick Responsible for keeping in CFS Surrounds and supports Dural sinuses and carries blood from brain towards heart 2 layers Lamellae – superficial layer that serves as skull’s inner periosteum Meningeal layer – deep layer; the actual Dura mater

http://medical-dictionary. thefreedictionary http://medical-dictionary.thefreedictionary.com/dorsal+root+of+spinal+nerve https://www.laserspineinstitute.com/back_problems/spinal_anatomy/spinal_cord/dorsal/