Question

Select the correct sequence of cranial meninges from the Inner (brain surface) to the Outer (skull) side:

• A. Piamater $\rightarrow$ Arachnoid membrane $\rightarrow$ Duramater
• B. Duramater $\rightarrow$ Arachnoid membrane $\rightarrow$ Piamater
• C. Arachnoid membrane $\rightarrow$ Duramater $\rightarrow$ Piamater
• D. Duramater $\rightarrow$ Piamater $\rightarrow$ Arachnoid membrane

Hint:

To avoid confusion, remember the simple word mnemonics:
- PAD for Inner to Outer: Pia $\rightarrow$ Arachnoid $\rightarrow$ Dura.
- DAP for Outer to Inner: Dura $\rightarrow$ Arachnoid $\rightarrow$ Pia.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to identify the correct sequence of the protective membranes (cranial meninges) that cover the brain, ordered specifically from the innermost layer (closest to the brain surface) to the outermost layer (closest to the skull).

Step 2: Detailed Explanation:

• The human brain and spinal cord are enclosed and protected by three distinct layers of connective tissue membranes called the cranial meninges.

• These three layers, from the deepest (internal) to the most superficial (external), are:

• Pia mater (Piamater): This is the innermost layer. It is extremely delicate, thin, and highly vascularized (rich in blood vessels). It is in direct contact with and closely adheres to the surface of the brain, following all its gyri and sulci.

• Arachnoid mater (Arachnoid membrane): This is the middle layer. It is a thin, web-like, avascular membrane. The space between the pia mater and the arachnoid membrane is called the subarachnoid space, which contains cerebrospinal fluid (CSF) that cushions the brain.

• Dura mater (Duramater): This is the outermost layer. It is a thick, tough, dense fibrous membrane that lines the inner surface of the skull bones, providing structural protection.

• The question asks for the sequence from Inner to Outer. Therefore, the correct sequence is:
\[ \text{Pia mater} \rightarrow \text{Arachnoid membrane} \rightarrow \text{Dura mater} \]

Step 3: Final Answer:
The correct inner-to-outer sequence of cranial meninges is Piamater $\rightarrow$ Arachnoid membrane $\rightarrow$ Duramater.