Meninges (or meninx in its singular form) are layers that provide protection to the central nervous system. While the spinal column, cranium and the rest of the central nervous system is protected by bones, meninges give an extra protection. It maybe a simple layer of connective tissue, but it has several number of functions in some parts of the central nervous system.
It has 3 basic forms namely: arachnoid, the dura mater and the pia mater.
It is known to be the middle meninges, as it is located between pia matter and the arachnoid matter. One of the contents filling the arachnoid is the cerebrospinal fluid. Its membrane is delicate and is very similar to a fine fishnet. The arachnoid is extended all throughout the central nervous system, and put its end on the brain fissures.
It consists of a connective tissue for the bone, and is located within the cranium. The dura mater is designed for extra protection having double layers. The first layer, located on the outer part is the periosteal layer. In some manner, it is adjoined with the cranium. The second layer on the other hand is the meningeal layer is the softer and thinner layer compared to the first one. It is not attached to the bone, but it is significant for the adhesion to the brain’s general contour.
The entire layer is nearly fused in the cranium’s dura mater. However, it has exceptions- there are times when it separates, for the dura mater to protect the dural sinuses. Because these dural sinuses are the ones responsible for gathering the venous blood in the brain, and draining it to the jugular veins on the neck- a very essential operation to keep the brain functioning normally.
In the cranium, the dura mater has four distinct regions. Its partitions are clearly noticeable, and these regions help attach the brain to the skull’s inner surface. In the spine, the dura mater is thick, and it adds a protective layer to the spinal cord.
Among all the meninges, the pia mater is the deepest one. The pia mater might be thin, but it aids in maintaining a tight bond to the brain’s convulsion and the spinal cord’s irregularities. It also consists of a specially modified connective tissue, and is intended to be vascular to support the nourishment of the brain cells, the spinal cord and other parts that surround it.
The pia mater also works with the arachnoid to help build one of the components of the ventricles- the roofs. It also contributes to the formation of choroid plexus, and to the attachment of dura mater to the spinal cord.