what are the 3 layers of the meninges
the arachnoid mater arachnoid mater pia mater the pia mater dura mater
title: Meninges text: Meninges The meninges (, "singular:" meninx ( or ), from , "adjectival:" meningeal ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in the subarachnoid space between the arachnoid mater and the pia mater. The primary function of the meninges is to protect the central nervous system. The dura mater () (also rarely called "meninx fibrosa" or "pachymeninx") is a thick, durable membrane, closest to the skull and vertebrae. The dura mater, the outermost part, is a loosely title: Meninges text: arranged, fibroelastic layer of cells, characterized by multiple interdigitating cell processes, no extracellular collagen, and significant extracellular spaces. The middle region is a mostly fibrous portion. It consists of two layers: the endosteal layer, which lies closest to the calvaria (skullcap), and the inner meningeal layer, which lies closer to the brain. It contains larger blood vessels that split into the capillaries in the pia mater. It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid mater. The dura mater is a title: Meninges text: the same animals, Sterzi demonstrated that, while in the spinal medulla the dura keeps its identity, in the skull it fuses with the periosteum. He also demonstrated the continuity of all meninges with the envelopes of nerves and with the filum terminale. Mammals (as higher vertebrates) retain the dura mater, and the secondary meninx divides into the arachnoid and pia mater. Meninges The meninges (, "singular:" meninx ( or ), from , "adjectival:" meningeal ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia title: Meninges text: inner surface toward the innermost collagenous portion of the arachnoid reticular layer. The pia mater () is a very delicate membrane. It is the meningeal envelope that firmly adheres to the surface of the brain and spinal cord, following all of the brain's contours (the gyri and sulci). It is a very thin membrane composed of fibrous tissue covered on its outer surface by a sheet of flat cells thought to be impermeable to fluid. The pia mater is pierced by blood vessels to the brain and spinal cord, and its capillaries nourish the brain. The arachnoid and pia mater title: Pia mater text: Pia mater Pia mater ( or ), often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. "Pia mater" is medieval Latin meaning "tender mother". The other two meningeal membranes are the dura mater and the arachnoid mater. Both the pia and arachnoid mater are derivatives of the neural crest while the dura is derived from embryonic mesoderm. Pia mater is a thin fibrous tissue that is impermeable to fluid. This allows the pia mater to enclose cerebrospinal fluid. By containing this fluid the pia mater works