Question

Given an account of the various protective layers and spaces surrounding the brain

Answer 1

Brain is protected by a bony covering known as the cranium and beneath the cranium are present three membranes of the connective tissue known as the meninges. There are three meninges surroundings the brain and spinal cord.
Three meninges around the brain are as follows:

a. Dura mater: It is the outermost meninx made up of dense irregular connective tissue. Dura mater is tightly attached to the cranial bones.

b. Arachnoid membrane: It is a thin layer and appears like a spider web.

c. Pia mater: It is a delicate membrane present below the arachnoid membrane and it is tightly attached the brain and spinal cord. It is separated from the arachnoid membrane via space known as the sub-arachnoid space.

Sub-arachnoid space is filled with shock absorbing cerebrospinal fluid.

Brain also has the cavities known as the ventricles. There are total four ventricles in the brain and are filled with cerebrospinal fluid. First and second ventricles are present inside the two cerebral hemispheres and are known as the lateral ventricles. Third ventricle is present inside the diencephalon. The two lateral ventricles are connected to the third ventricle through two interventricular foramina. The fourth ventricle is located inside the inferior part of the pons and superior part of the medulla. The fourth ventricle is connected to the third ventricle through a narrow canal known as the cerebral aqueduct which passes through the midbrain.