Meningina is a term used in biology and anatomy to refer to a protective layer or membrane that surrounds the central nervous system, consisting of the brain and spinal cord. It generally denotes the meninges, which are three layers of membranes found between the bony encasements of the cranium and vertebral column, and the delicate neural tissue. These three layers, from outer to inner, are the dura mater, arachnoid mater, and pia mater.
The outermost layer, the dura mater, is a thick and tough membrane that provides physical strength and protection. It serves as a barrier between the brain and the cranial bones and is involved in the formation of certain structures, such as venous sinuses.
Beneath the dura mater is the arachnoid mater, a delicate membrane that helps cushion the brain and spinal cord through the production and circulation of cerebrospinal fluid. The arachnoid mater also participates in the absorption of excess cerebrospinal fluid.
The innermost layer, the pia mater, adheres closely to the surface of the brain and spinal cord, providing support and nourishment to the underlying neural tissues. It contains numerous blood vessels that supply nutrients and oxygen to the central nervous system.
Together, these three layers of the meningina protect the central nervous system from mechanical damage, infections, and chemical imbalances. They aid in maintaining the delicate equilibrium required for proper neuronal function and play a crucial role in the overall health and viability of the central nervous system.
