Question

The outer membrane that covers the brain is
A. Myelin Sheath
B. Duramater
C. Arachnoid membrane
D. Piamater

Answer 1

Hint: The brain is a delicate organ in human beings which is protected by a skull. Being soft in nature, it is protected by membranous coverings known as Meninges. These meninges perform two main functions such as provision of framework for cerebral vasculature and protection of the central nervous system from mechanical damage with assistance from cerebrospinal fluid.

Complete answer:
The outer membrane that covers the brain is known as Dura mater. So, option B is the correct answer.
The meninges of the brain are divided into three layers which are explained below:

A. Dura mater-
It is the outermost layer of meninges.
It is a thick layer and tough by nature.
It contains two connective tissue sheets- The periosteal layer ( inner surface of bones of the cranium) and the Meningeal layer (only layer in the vertebral column).
The dural venous sinuses are located between these two layers. This is responsible for the venous vascular system of the cranium.
It receives vasculature from the middle meningeal artery and vein.
Dural reflections are also formed in some areas of the brain by inward folding of the dura mater. The cranial cavity is separated into several compartments.
Dura mater is involved in two types of hematoma (collection of blood)- Extradural and subdural.
B. Arachnoid mater
It is the middle layer of the meninges, lying directly below the dura mater.
It is made of layers of connective tissue.
It is avascular and is devoid of any innervation.
Underneath it is a space known as the subarachnoid space.
It contains cerebrospinal fluid, which functions as the cushion of the brain.
C. Pia mater
It is located below the subarachnoid space.
It is a thin layer.
It is tightly bounded with the brain and spinal cord.
It is the only covering which follows the fissures of the brain.
It is vascularised highly with blood vessels.

Note: Dura Mater is the outermost covering of the brain and is a part of meninges. It not only covers the brain but is also a covering of the spinal cord consisting of a well-supplied cerebral vasculature.
The inflammation of the meninges is known as meningitis. It is usually caused by a bacterial pathogen eg- Streptococcus pneumonia.