Meninges (sing. meninx) Membranes that line the CNS (brain and spinal cord) Three layers Dura mater—outermost Arachnoid mater—middle Pia mater—inside layer Cerebrospinal fluid (CSF)—in subarachnoid space

Spinal Cord The slender nerve column that passes from the brain to the bottom of the vertebral canal Begins where tissue leaves the foramen magnum 31 segments that give rise to spinal nerves

Spinal cord Gray matter-unmyelinated White matter—myelinated Nerve tracts—bundles of myelinated nerve fibers that make up major nerve pathways Central canal-contains CSF

Cross Section of a spinal cord

Spinal Cord Functions Conduct nerve impulses into and away from peripheral nerves Ascending tracts carry sensory information to the brain Descending tracts conduct motor impulses from brain to muscles or glands Center for spinal reflexes Reflex arcs that do not travel to brain