Now that I have that out of the way we can concentrate on the meninges which is a tough, fluid containing membrane that surrounds the brain and spinal cord and is a protective barrier. There are three layers to the meninges they are Dura Matter, Arachnoid Matter, and finally Pia Matter. Dura matter is the tough outer layer of the meninges. Arachnoid is the middle layer of the meninges which is a cobweb-like structure with fluid that occupies the spaces in between the cobweb-like strands and Pia Matter which is the innermost layer of the membrane usually covering the spinal cord.

Cerebrospinal fluid which is one of the body’s circulating fluids is formed from blood and reabsorbed into the fluid. The cerebrospinal fluid is between the pia matter and the arachnoid matter of the brain. Cerebrospinal fluid fills the ventricles or large spaces which lie deep inside the brain. The network of brain capillaries that filters the Cerebrospinal fluid out of the blood is called the choroid plexus. Excess or sometimes called “water on the brain” is a condition called hydrocephalus.

Connecting the brain and spinal cord to various internal organs, glands and muscle in the thoracic and abdomen are cranial and spinal nerves. These nerves serve the brain by communicating with cardiac and smooth muscles as well in the Autonomic nervous system or involuntary actions of the body.  In the surface of the skin a surface area that is supplied by a single spinal nerve is called a dermatone. Now for some numbers that you should now about the number of nerves in the body.

There are 8 pairs of cervical nerves.

There are 12 pairs of thoracic nerves.

There are 5 pairs of lumbar nerves.

There are 5 pairs of sacralspinal nerves.

There are 1 pair of coccygeal nerves.