Meninges of the brain (coronal section) (English)

Coronal section through a portion of the skull, meninges and cerebral cortex. The cranial dura mater is composed of two layers: the outer periosteal layer (which adheres tightly to the skull, also known as the endocranium) and inner meningeal layer. The two dural layers are usually directly apposed to one another, except in places where they separate to form the dural venous sinuses, which is represented in this image by the superior sagittal sinus. Deeper to the dura mater is the arachnoid mater with its small protrusions known as arachnoid granulations, that pierce the inner layer of the dura projecting into the lumen of the superior sagittal sinus. The pia mater is a thin membrane composed of a single cell layer which, unlike the dura and arachnoid mater, closely follows all contours (i.e. gyri and sulci) of the brain. Thin projections of connective tissue called arachnoid trabeculae extend from the inner surface of the arachnoid mater, traverse the subarachnoid space and attach to the outer surface of the pia mater. The subdural space is a potential space that can be opened by the separation of the arachnoid from the dura as a result of trauma or other ongoing pathological process; in an healthy state both meninges are adhered to each other and the subdural space is obliterated. The subarachnoid space, between the arachnoid and pia mater, is a fluid-filled space occupied by CSF. Cerebral blood vessels pass through this space, however are enveloped in a layer of leptomeningeal epithelial cells (not shown in image) and thus are not in contact with the CSF. Underneath the pia mater is the thin subpial space which separates it from the glial limiting membrane of the cerebral cortex.