What is the name of the inner layer of the brain membrane that is the thinnest?

The inner layer of the brain membrane that is the thinnest is known as the pia mater. This membrane closely adheres to the surface of the brain and spinal cord, providing a protective layer while also allowing for the passage of blood vessels that supply nutrients and oxygen to the nervous tissue. The pia mater plays a crucial role in maintaining the health of the brain by covering its delicate structures and helping to form the barrier between the brain tissue and the cerebrospinal fluid. Its thinness is significant, as it ensures that vital substances can readily exchange between the blood and the nervous tissue while still providing protection.

In contrast, the dura mater is a much thicker outer layer that serves as a tough protective barrier, and the arachnoid mater, which sits between the dura mater and pia mater, is a web-like structure that also contributes to the protective environment of the brain but is thicker than the pia mater. The cerebrum, while an essential part of the brain, is not a membrane but rather a major component of the brain responsible for higher brain functions.