GROSS ANATOMY

Detailed explanation-1: -The middle layer is the arachnoid, a web-like structure filled with fluid that cushions the brain. The tough outer layer is called the dura mater .

Detailed explanation-2: -The subarachnoid space consists of the cerebrospinal fluid (CSF), major blood vessels, and cisterns. The cisterns are enlarged pockets of CSF created due to the separation of the arachnoid mater from the pia mater based on the anatomy of the brain and spinal cord surface.

Detailed explanation-3: -The subdural space is the space that potentially exists between the meningeal layer of the dura and the arachnoid mater. Similar to the epidural space, the subdural space typically exists only under pathological conditions.

Detailed explanation-4: -There are two subdivisions of arachnoid mater surrounding the subarachnoid space, the dorsal layer and the ventral layer.

Detailed explanation-5: -The middle layer of meninges is arachnoid, a thin layer resembling a cobweb with numerous threadlike strands attaching it to the innermost layer. The space under the arachnoid, the subarachnoid space, is filled with cerebrospinal fluid and contains blood vessels. The pia mater is the innermost layer of meninges.