Objectives To learn protective parts/features of CNS To learn structure and function of the Spinal Cord To understand the brain structure and function as well as development.
Protection of the CNS Bones Meninges
Protection of the CNS The brain & spinal cord are protected by bones, membranes, and fluid Bones A. Bones –*8 skull bones encase the brain –*30 vertebrae encase the spinal cord
Can you name the bones?
Meninges –B.) Meninges - Membranes surrounding CNS 3 Layers encasing the brain –a.) Dura mater »outermost membrane: attached to periosteum of the skull »contains many blood vessels & nerves »tough, white fibrous connective tissue
–b.) Arachnoid Mater »middle layer »thin net-like membrane »No blood vessels »Sub-arachnoid space lies deep to this layer and is filled with CSF which serves as a cushion for brain
–c.) Pia Mater »inner layer that clings to brain surface »very thin delicate connective tissue »many nerves & blood vessels = nourishment »dips into grooves and contours inner layer that clings to brain surface –erves & blood vessels = nourishment»dips into grooves and contours–erves & blood vessels = nourishment»dips into grooves and contours
Meningitis What does the word Mean? Caused by: –Bacteria or virus Affects: –Mainly arachnoid and pia maters –Younger or older generations –People with suppressed immune systems Complications of disease: –Loss of vision, hearing paralysis, mental retardation…death
C. Ventricles –Interconnected cavities within the cerebral hemispheres and brain stem –Continuous with central canal of spinal cord –Filled with CSF cerebral spinal fluid
–D. Cerebrospinal Fluid (CSF) –Secreted by Choroid Plexus –Circulation: Ventricles 1&2 --> 3rd --> 4th --> central canal --> reabsorbed into bloodstream –Approx. 1 liter is secreted daily: Secreted and reabsorbed continuously –Functions: cushion & circulation of nutrients/wastes
The Brain Structures and Functions
Forebrain prosencepahlon Includes hypothalamus, thalamus and cerebrum
Midbrain mesencephalon Connects cerebrum to spinal cord Reflex center for eye and some head movements