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In anatomy, the meninges (/ m ə ˈ n ɪ n dʒ iː z /; [1] [2] sg. meninx / ˈ m iː n ɪ ŋ k s, ˈ m ɛ n ɪ ŋ k s /; [3] from Ancient Greek μῆνιγξ (mêninx) 'membrane') [4] 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.
The dura mater has two layers, an outer periosteal layer closely adhered to the neurocranium, and an inner meningeal layer known as the dural border cell layer. [1] The two dural layers are for the most part fused together forming a thick fibrous tissue membrane that covers the brain and the vertebrae of the spinal column. [2]
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 arachnoid mater is interposed between the two other meninges, the more superficial (closer to the surface) and much thicker dura mater and the deeper pia mater, from which it is separated by the subarachnoid space. The delicate arachnoid layer is not attached to the inside of the dura but against it, and surrounds the brain and spinal cord.
Within the meninges the brain and spinal cord are bathed in cerebral spinal fluid which replaces the body fluid found outside the cells of all bilateral animals. In vertebrates, the CNS is contained within the dorsal body cavity, while the brain is housed in the cranial cavity within the skull. The spinal cord is housed in the spinal canal ...
Sectional organization of spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. [3] [4] Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, and continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous ...
There are many cisterns in the brain with several large ones noted with their own name. At the base of the spinal cord is another subarachnoid cistern: the lumbar cistern which is the site for a lumbar puncture. Some major subarachnoid cisterns: Cisterna magna also called cerebellomedullary cistern - the largest of the subarachnoid cisterns.
It is the space within the thecal sac which extends from below the end of the spinal cord (the conus medularis), typically at the level of the first to second lumbar vertebrae down to tapering of the dura at the level of the second sacral vertebra. The dura is pierced with a needle during a lumbar puncture (spinal tap).