What are the three layers of the meninges, and what are their key characteristics?

The meninges are three protective layers around the brain and spinal cord. From outermost to innermost: Dura mater is tough and fibrous, arachnoid mater is delicate and transparent, and pia mater is vascular and adherent to CNS tissue.

How is cerebrospinal fluid (CSF) produced and circulated in the brain?

CSF is primarily produced by choroid plexuses in the lateral ventricles, with about 500 ml formed daily. It circulates from the lateral ventricles to the third and fourth ventricles, then exits into the subarachnoid space, where it moves upward and is absorbed via arachnoid villi into the venous sinuses.

What is the function of the subarachnoid space and cisterns?

The subarachnoid space, filled with CSF, acts as a shock absorber and buffer for the CNS. Cisterns are enlarged areas of this space that serve as CSF reservoirs, such as the cerebellomedullary cistern (largest) and pontine cistern, aiding in fluid distribution and clinical procedures like cisternal puncture.

What role do arachnoid villi and granulations play in CSF dynamics?

Arachnoid villi and granulations are structures that protrude from the arachnoid mater into dural venous sinuses. They are critical for CSF absorption, allowing fluid to drain from the subarachnoid space into the bloodstream, primarily at the superior sagittal sinus.

What is hydrocephalus, and how is it classified?

Hydrocephalus is the abnormal accumulation of CSF in the skull. It is classified into two types: Non-communicating (internal) hydrocephalus is caused by a blockage in the ventricular system, while communicating (external) hydrocephalus is due to impaired CSF absorption at arachnoid villi.

What are the main functions of cerebrospinal fluid (CSF)?

CSF serves several key functions: It acts as a cushion and shock absorber for the CNS, provides buoyancy to reduce brain weight, and helps maintain intracranial pressure and waste clearance.

Meninges & CSF – Dura, Arachnoid, Pia + Cisterns