In human anatomy, the tough outermost meningeal membrane that closely lines the inside of the skull and covers the brain is called

Introduction:
The human brain and spinal cord are protected by three connective tissue membranes collectively known as the meninges. These layers cushion the central nervous system and help maintain the cerebrospinal fluid environment. This question asks you to identify the name of the outermost protective membrane that lies just beneath the skull and forms the outer covering of the brain.

Given Data / Assumptions:
- The context is the protective coverings of the brain, known as meninges. - The options include myelin sheath, dura mater, arachnoid membrane and pia mater. - We assume standard human anatomy terminology with three meningeal layers. - The question focuses specifically on the outermost membrane above the brain surface.

Concept / Approach:
The meninges consist of three layers, from outside to inside: dura mater, arachnoid mater (or arachnoid membrane) and pia mater. The dura mater is the tough, fibrous outer layer that adheres closely to the inner surface of the skull. The arachnoid membrane is the middle, web like layer, and the pia mater is the delicate inner layer that is tightly attached to the brain surface. The myelin sheath, by contrast, is an insulating layer around nerve fibres, not a meningeal covering. Therefore, the outer membrane that covers the brain is the dura mater.

Step-by-Step Solution:
Step 1: Recall that meninges are membrane layers around the brain and spinal cord, named dura mater, arachnoid mater and pia mater. Step 2: Arrange them in order from outermost to innermost: dura mater (outer), arachnoid membrane (middle) and pia mater (inner). Step 3: Note that dura mater is described as thick, tough and fibrous, forming a protective sac. Step 4: Recognise that the question asks for the outer membrane just beneath the skull, which matches dura mater. Step 5: Eliminate myelin sheath because it covers individual nerve fibres, not the entire brain.

Verification / Alternative check:
Anatomy textbooks and diagrams show a clear cross section of the skull and brain. The sequence is skull bone, followed by dura mater, then arachnoid membrane, the subarachnoid space containing cerebrospinal fluid, and finally pia mater closely investing the brain. Clinical descriptions of subdural and extradural haemorrhages also refer to the dura mater as the outer meningeal layer. These consistent references confirm that dura mater is the correct answer.

Why Other Options Are Wrong:
Myelin sheath: An insulating layer around axons that increases conduction speed, not a membrane that wraps the brain as a whole. Arachnoid membrane: The middle meningeal layer, lying between dura mater and pia mater, not the outermost one. Pia mater: The innermost meningeal layer that adheres directly to the brain surface and follows its folds, not the outer covering.

Common Pitfalls:
Students sometimes confuse the order of the meningeal layers because all three names sound similar and include the word mater. Another mistake is to choose arachnoid membrane, thinking of its web like appearance as an outer covering. A helpful memory aid is to think of the phrase tough mother for dura mater as the strong outside layer, spider web for arachnoid in the middle, and gentle mother for pia mater as the delicate inner layer that touches the brain.

Final Answer:
The outermost membrane that covers the brain is the Dura mater.