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The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web . The arachnoid mater is a derivative of the neural crest mesoectoderm in the embryo.
The bases of denticulate ligaments arise in the pia mater and are firmly attached to the arachnoid mater and dura mater at the apex. [2] The denticulate ligaments extend across the subarachnoid space between anterior nerve roots and posterior nerve roots, piercing the intervening spinal arachnoid mater to reach the dura.
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.
The middle element of the meninges is the arachnoid mater, or arachnoid membrane, so named because of its resemblance to a spider web. It cushions the central nervous system. This thin, transparent membrane is composed of fibrous tissue and, like the pia mater, has an outer layer of tightly packed flat cells, forming the arachnoid barrier. [8]
In the skull, the periosteal layer of the dura mater adheres to the inner surface of the skull bones while the meningeal layer lays over the arachnoid mater. Between them is the epidural space . The two layers of the dura mater separate at several places, with the meningeal layer projecting deeper into the brain parenchyma forming fibrous septa ...
The membranes are the tough dura mater; the middle arachnoid mater and the more delicate inner pia mater. 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 ...
CSF returns to the vascular system by entering the dural venous sinuses via arachnoid granulations. [2] These are outpouchings of the arachnoid mater into the venous sinuses around the brain, with valves to ensure one-way drainage. [2] This occurs because of a pressure difference between the arachnoid mater and venous sinuses. [3]
Medical intervention Epidural administration A freshly inserted lumbar epidural catheter. The site has been prepared with tincture of iodine, and the dressing has not yet been applied. Depth markings may be seen along the shaft of the catheter. ICD-9-CM 03.90 MeSH D000767 OPS-301 code 8-910 [edit on Wikidata] Epidural administration (from Ancient Greek ἐπί, "upon" + dura mater) is a method ...