Question

which of the following pairs is mismatched?
a dura mater—tough, fibrous outer sac
b subdural space—space containing cerebrospinal fluid
c pia mater—innermost layer, lies directly on the brain
d arachnoid layer—attached to the pia mater by weblike filaments

Explanation:

• Dura mater: It is the tough, fibrous outer sac of the meninges. So, option A is correctly matched.
• Subdural space: It is a potential space between the dura mater and the arachnoid mater. The space that contains cerebrospinal fluid is the sub - arachnoid space (between the arachnoid mater and the pia mater), not the subdural space. So, option B is mismatched.
• Pia mater: It is the innermost layer of the meninges and lies directly on the brain. So, option C is correctly matched.
• Arachnoid layer: It is attached to the pia mater by web - like filaments (arachnoid trabeculae). So, option D is correctly matched.

Answer:

B. subdural space—space containing cerebrospinal fluid