what connects the pia mater to the dura mater of the spinal cord
Pia mater The spinal pia mater closely follows and encloses the curves of the spinal cord, and is attached to it through a connection to the anterior fissure. The pia mater attaches to the dura mater through 21 pairs of denticulate ligaments that pass through the arachnoid mater and dura mater of the spinal cord. These denticular ligaments help to anchor the spinal cord and prevent side to side movement, providing stability.[7] The membrane in this area is much thicker than the cranial pia mater, due to the two-layer composition of the pia membrane. The outer layer, which is made up of mostly connective tissue, is responsible for this thickness. Between the two layers are spaces which exchange information with the subarachnoid cavity as well as blood vessels. At the point where the pia mater reaches the conus medullaris or medullary cone at the end of the spinal cord, the membrane extends as a thin filament called the filum terminale or terminal filum, contained within the lumbar cistern. This filament eventually blends with the dura mater and extends as far as the coccyx, or tailbone. It then fuses with the periosteum, a membrane found at the surface of all bones, and forms the coccygeal ligament. There it is called the central ligament and assists with movements of the trunk of the body.[6]