Changes

This is the innermost layer and is firmly bound to the underlying neural tissue of the brain and spinal cord. The inner surface of the brain facing this meningial layer is lined with ependymal cells. The pia mater is highly vascular and is formed from delicate connective tissue. It also contains arteries and veins, but not venous sinuses.

This is the innermost layer and is firmly bound to the underlying neural tissue of the brain and spinal cord. The inner surface of the brain facing this meningial layer is lined with ependymal cells. The pia mater is highly vascular and is formed from delicate connective tissue. It also contains arteries and veins, but not venous sinuses.

===Cerebrospinal Fluid===

===Cerebrospinal Fluid===

Cerebrospinal fluid ('''CSF''') surrounds the brain as well as the central canal of the spinal cord in the subarachnoid space. It helps cushion the central nervous system (CNS), acting in a similar manner to a shock absorber. It also acts as a chemical buffer providing immunological protection and a transport system for waste products and nutrients. The CSF also provides buoyancy to the soft neural tissues which effectively allows the neural tissue to "float" in the CSF. This prevents the brain tissue from becoming deformed under its own weight. It acts as a diffusion medium for the transport of neurotransmitters and neuroendocrine substances.

Cerebrospinal fluid ('''CSF''') surrounds the brain and spinal cord. It helps cushion the central nervous system (CNS), acting in a similar manner to a shock absorber. It also acts as a chemical buffer providing immunological protection and a transport system for waste products and nutrients. The CSF also provides buoyancy to the soft neural tissues which effectively allows the neural tissue to "float" in the CSF. This prevents the brain tissue from becoming deformed under its own weight. It acts as a diffusion medium for the transport of neurotransmitters and neuroendocrine substances.

====Production====

====Production====

CSF is a clear fluid produced by dialysis of blood in the ''choroid plexus''. Choroid plexi are found in each lateral ventricle and a pair are in the third and fourth ventricle. Further production also comes from the ependymal cell linings and vessels within the pia mater.  

CSF is a clear fluid produced by dialysis of blood in the ''choroid plexus''. Choroid plexi are found in each lateral ventricle and a pair are in the third and fourth ventricle. Further production also comes from the ependymal cell linings and vessels within the pia mater.