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Pia mater is medieval Latin meaning "tender mother". [1] 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. The pia mater is a thin fibrous tissue that is permeable to water and small solutes.
The pia mater is the innermost protective layer. It is very delicate and it is tightly associated with the surface of the spinal cord. The cord is stabilized within the dura mater by the connecting denticulate ligaments, which extend from the enveloping pia mater laterally between the dorsal and ventral roots.
The brain and spinal cord are covered by the meninges, the three protective membranes of the tough dura mater, the arachnoid mater and the pia mater. The cerebrospinal fluid (CSF) within the skull and spine provides further protection and also buoyancy, and is found in the subarachnoid space between the pia mater and the arachnoid mater.
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.
Leptomeningeal collaterals lie within the leptomeninges, the two deep layers of the meninges called the pia mater and the arachnoid mater. [4] Their diameter has been measured at approximately 300 micrometers, [ 5 ] but there is variability between individuals in the size, quantity and location of these vessels, and between either hemisphere ...
Although the pia mater adheres to the surface of the brain, closely following the contours of its gyri and sulci, the arachnoid mater only covers its superficial surface, bridging across the gyri. This leaves wider spaces between the pia and arachnoid and the cavities are known as the subarachnoid cisterns. [citation needed]
Between the arachnoid mater and the pia mater is the subarachnoid space and subarachnoid cisterns, which contain the cerebrospinal fluid. [11] The outermost membrane of the cerebral cortex is the basement membrane of the pia mater called the glia limitans and is an important part of the blood–brain barrier. [12]
The arachnoid mater covering the brain is referred to as the arachnoidea encephali, and the portion covering the spinal cord as the arachnoidea spinalis. The arachnoid and pia mater are sometimes considered as a single structure, the leptomeninx, or the plural version, leptomeninges (lepto, from the Greek root meaning "thin" or "slender").