Nervous tissue is very delicate, and since it has a vital function in our body, we need to protect it. In the central nervous system, the first layer of protection is the skull and the vertebral column, which physically enclose the brain and the spinal cord in thick bone.
The brain and spinal cord are also covered by three layers of thin membranes, called meninges. The most superficial meningeal layer is called the dura mater, the middle layer is called the arachnoid mater, and the delicate inner layer is called the pia mater.
The cerebrospinal fluid, CSF circulates in the ventricles, the subarachnoid space, and the central canal of the spinal cord. This fluid is produced in the ventricles, which are interconnected cavities in the brain. It has shock-absorbing qualities and circulates nutrients.
The blood-brain barrier provides inner protection: It prevents toxins and harmful pathogens in the blood from entering the brain.
Figure 1: Protection of the Central Nervous System