Question

The membranes enclosing the brain and spinal cord are known as
A. Meninges
B. Meningitis
C. Nephron
D. axon

Answer 1

Hint:The membrane with three consecutive layers covering encircles the brain and spinal cord. This membrane is moist with CSF or cerebrospinal fluid.

Complete answer:
The brain and spinal cord together form the central nervous system (CNS).
They are protected by a membrane known as meninges. It is a three layers protective covering.
Dura mater is the outermost layer. It is composed of dense irregular connective tissue.
The middle layer is known as the arachnoid mater. It is an avascular covering and forms an arrangement of collagen fibers and elastic fibers.
The innermost layer is the pia mater. It is a thin connective tissue layer that attaches to the surface of the brain and spinal cord.
Subarachnoid space is present between the arachnoid mater and pia mater. It is filled with cerebrospinal fluid.

So, the correct answer is option A. Meninges.

Additional information:
Although both brain and spinal cord are surrounded by meanings, the meninges surrounding the brain are known as cranial meninges and those surrounding the spinal cord are known as spinal meninges.
The cranial dura mater has two layers and the spinal dura mater has only one layer.
Meningitis term is associated with inflammation of meninges.

Note: The terms meninges and meningitis have different meanings – the first one is the membrane of the brain and the second one is a disease of that membrane.