CNS Structures Meninges Spinal cord Brain

Meninges Membranes between the bone and soft tissues of the nervous system Function: ? 3 layers: Orange analogy Dura mater Arachnoid mater Pia mater Meningitis (?)

Dura Mater Outermost layer Contains many blood vessels and nerves Attaches to the inside of the cranial cavity and forms the internal periosteum (???) of the surrounding skull bones Forms partitions between lobes of the brain Continues into vertebral canal Terminates as a blind sac below the end of the spinal cord

Arachnoid Mater Thin, weblike membrane located between dura and pia maters Lacks blood vessels Spreads over brain and spinal cord, but does not dip into grooves and depressions on their surfaces

Pia Mater Cerebrospinal fluid (CSF) – clear, watery fluid that fills space between arachnoid and pia maters Pia mater – very thin and contains many nerves and blood vessels that nourish cells of the brain and spinal cord Hugs surfaces and follows all irregular contours of brain and spinal cord Subdural hematoma (?)

Spinal Cord Slender nerve column that passes downward from the brain into the vertebral canal Starts at the foramen magnum and ends between first and second lumbar vertebrae

Structure of Spinal Cord 31 segments that each give rise to a pair of spinal nerves

Functions of the Spinal Cord What do you think would be the functions of the spinal cord? Conducting nerve impulses Serving as a center for spinal reflexes Nerve tracts (major nerve pathways) of the spinal cord are made up of axons that provide 2-way communication between brain and body parts: Ascending tracts - sensory information to brain Descending tracts – motor impulses from brain