Question

Give the function of the meninges.

Answer 1

Meninges are formed by three tissue membranes that are primarily known as wrappers of the brain. These meninges consist of dura mater, arachnoid, and pia mater. Meninges are essential for the correct development of the central nervous system.

Complete answer:
-Meningeal tissue has been proven to be required for encephalon development.
-The mesodermal components of the forebrain meninges gives the endothelial walls of blood vessels which can penetrate the neuroepithelium, while the neural crest emerging from the posterior neural folds yields pericytes and connective tissue.
-The removal of the posterior diencephalic and mesencephalic neural folds prevents meninges’ development and results in apoptosis of the neuroepithelium of the whole forebrain.
-Etchevers have shown that the presence of primitive leptomeninges is needed for the survival and subsequent growth of the developing a prosencephalon.
-When the neural folds are ablated, paraxial mesoderm that can replace the neural crest cells generating primitive leptomeninges which results in allowing encephalon development.
-During the development, destruction of the meninges overlying in the cerebellum which can lead to cerebellar hypoplasia, the formation of neuronal ectopia, and gliosis in the subarachnoid space and causes reduction of the total number of granular cells.
-Dura Mater: The meningeal layer also forms dural folds that divide the cranial cavity into different compartments, which support and house various subdivisions of the brain. Cranial dura forms tubular sheaths that cover cranial nerves within the skull.
-Arachnoid Mater: This is connected to the meninx through tiny fibrous extensions that span the space between the 2 layers. Space provides a route for the passage of blood vessels and nerves through the brain and collects spinal fluid that flows from the ventricle. Arachnoid granulations remove spinal fluid from the space and send it to the dural venous sinuses, where it's reabsorbed into the venous system.
-Pia Mater: The pia mater which is rich in blood vessels, which provide nutrients to nervous tissue. This layer also contains the choroid plexus, a network of capillaries and ependyma which is a specialized ciliated epithelial tissue) that produce cerebrospinal fluid.

Note: -The dura or pachymeninx (patchy-thick) is the outer membrane and forms a sac that envelops the opposite meningeal layers.
-The dura matter surrounds and supports the dural venous sinuses and it reflects in three infoldings, the primary separating the 2 hemispheres of the cortex.
-The second between the cerebellum and the occipital lobe that is tentorium cerebelli and falx cerebelli.
-The third covers the pituitary gland and the sella turcica.