Meningeal

Meningeal is an adjective relating to the meninges, the protective membranes that enclose the brain and spinal cord. The meninges provide protection, support blood vessels, and help compartmentalize the central nervous system. The term is used in anatomy and medicine to describe structures and processes associated with these coverings.

The meninges consist of three layers: dura mater (the tough outer membrane), arachnoid mater (a delicate, web-like middle layer), and pia mater (the inner layer that closely follows the surface of the brain and spinal cord). The space between the dura and arachnoid is the subdural space, and the space between the arachnoid and pia is the subarachnoid space, which contains cerebrospinal fluid and major vessels. Meningeal structures include arteries and veins that supply and drain the meninges, as well as lymphatic pathways involved in cerebrospinal fluid circulation.

Clinically, inflammation or infection of the meninges is termed meningitis, and signs of meningeal irritation can include neck stiffness, headache, and sensitivity to light. Other conditions involve the meninges, such as meningiomas, tumors arising from meningeal cells, which are typically extra-axial and slow-growing. Metastatic spread to the meninges is described as meningeal (or leptomeningeal) carcinomatosis. In imaging and diagnosis, assessment of the meninges helps distinguish intracranial processes affecting the protective coverings from those within the brain tissue itself.