Which layer of the meninges is the tough outer layer?

The tough outer layer of the meninges is the dura mater. This layer is composed of dense connective tissue, which provides a protective barrier for the brain and spinal cord. The dura mater is the most durable of the three layers of meninges, which also include the arachnoid membrane and the pia mater. It adheres closely to the inner surface of the skull and the vertebral canal, playing a crucial role in protecting the delicate neural structures within. Its tough and fibrous nature helps to shield the brain from mechanical impacts and potential injuries.

In contrast, the arachnoid membrane is a more delicate membrane located beneath the dura mater, and while it serves a protective role, it lacks the toughness of the dura. The pia mater is the innermost layer, closely enveloping the brain and spinal cord, consisting of areolar connective tissue, which allows it to be highly vascular and in contact with the nervous tissue itself. The cerebrum, referenced in one of the choices, is not a layer of the meninges but rather the largest part of the brain, responsible for higher cognitive functions, sensory perception, and voluntary movement.