The Meningeal Layers of the Human Brain!
present to you, The Meningeal Layers of the Human Brain! 'Meningeal layers consist of the pia mater, arachnoid mater, and the dura mater! The meningeal layers cover the brain and spinal cord! Main function of the meningeal layers is to protect the brain and spinal cord! . The pia mater is the meningeal envelope that firmly adheres to the surface of the brain and spinal cord.lt is a very thin membrane composed of fibrous tissue covered on its outer surface by a sheet of flat cells which is thought to be impermeable to fluid. The pia mater is pierced by blood vessels that travel to the brain and spinal cord. Over the pia mater and separated from it by a space called the subarachnoid space is the arachnoid, a thin, transparent membrane. It is composed of fibrous tissue and, like the pia mater, is covered by flat cells also thought to be impermeable to fluid. The arachnoid does not follow the convolutions of the surface of the brain and so looks like a loosely fitting sac. In the region of the brain, particularly, a large number of fine filaments called arachnoid trabeculae pass from the arachnoid through the subarachnoid space to blend with the tissue of the pia mater. The arachnoid trabeculae are embryologic remnants of the common origin of the arachnoid and pia mater, and they have the frail structure characteristic of these two of the meninges. The pia mater and arachnoid together are called the leptomeninges. The outermost of the three meninges is the dura mater, a strong, thick, and dense membrane. It is composed of dense fibrous tissue, and its inner surface is covered by flattened cel|s like those present on the surfaces of the pie mater and arachnoid. The dura mater is a sac that envelops the arachnoid and has been modified to serve several functions. The dura mater surrounds and supports the large venous channels (dural sinuses) carrying blood from the brain toward the heart.
