Introduction

Cerebrospinal fluid is a clear and colourless liquid, low in protein composition that is actively secreted in specific areas of the central nervous system (CNS) and surrounds the brain and spinal cord. There are 3 meninges (layers) covering the CNS whose primary function is to protect it. These 3 meninges are:

• Dura mater
• Arachnoid mater
• Pia mater

Cerebrospinal fluid flows between the arachnoid mater and pia mater meninges in an area called the subarachnoid space.

Image courtesy of Wikimedia Commons under the Creative Commons Attribution License

Cerebrospinal fluid constitutes all the intracerebral, interventricular and intracisternal content. It is also present within sulci and the central canal of the spinal cord. Within the brain are fluid-filled caverns and canals that constitute the ventricular system through which cerebrospinal fluid also flows.

Animation courtesy of Wikimedia Commons under the Creative Commons Attribution License

Intraentricular system of the brain

Red areas of the animation indicate the 2 lateral ventricles.

Blue areas of the animation indicate the interventricular foramina, third ventricle, cerebral aqueduct and fourth ventricle