Meninges

The brain sits inside the skull, and the spinal cord inside the backbone. Bone alone would bruise soft nerve tissue. So three layers wrap both, from outside in:

• Dura mater: the outer layer, tough and thick.
• Arachnoid: the middle layer, thin like a web.
• Pia mater: the inner layer, soft and close to the brain.

A clear liquid, the cerebrospinal fluid, fills the space between the inner layers. It acts as a cushion against shocks and brings food to the nerve cells.

A small example

A child falls off a bicycle and bumps her head. The skull takes the blow. The meninges and the fluid inside them soften what reaches the brain, like the packing around a phone in its box.

Where marks go

The 2025 ICSE Biology paper asked for the collective term for the brain's protective membranes. In CISCE's report on the 2025 Biology paper, examiners note answers that listed the three layers instead of the one word asked for, "meninges". Listing more than asked does not replace the term.

Diagrams of the brain and spinal cord need care too. A marking scheme gives marks for correct, named labels, so place grey matter and white matter the right way round. In the brain, grey matter is outside. In the spinal cord, it is inside. See how to write answers that earn full marks.

About the author

Deepti Sardana

Founder Member & Academic Lead

An IIT alumna (M.Sc., M.Phil.) with over 25 years in teaching, child psychology and learning assessment. As Academic Lead at EduBrahma, she leads the method TRUtesting uses to find where and why a child loses marks.

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