The meninges

Information

The brain and spinal cord are both wrapped with three layers of connective tissue membranes, collectively called the meninges. The three layers around the brain and the spinal cord have the same names in both locations, although the composition of the individual layers show a few slight differences depending on which location they are found in.

The outer layer is the toughest and thickest. It is called the dura mater (“DUR-ah MAY-ter”.) The middle layer is the arachnoid mater (“ah-RACK-noid MAY-ter”.) The inner-most layer lays directly on the nervous tissue of the brain or spinal cord, and is called the pia mater (“PIE-ah MAY-ter”.) There is space between the inner-most pia mater and the arachnoid mater. The space is filled with cerebrospinal fluid.

The meninges.

Figure 10-10. The three meninges layers covering the brain.