Online Lesson

SPH405

SPH405 : The Class : Gross Anatomy : Central Nervous System II : Online Lesson 1

Neurological Foundations of Speech, Language and Hearing

Online Lesson
Cerebrospinal Fluid

GOAL: To present the form and function of the ventricular system.

Objectives:

Relate the four ventricles to their associated central nervous system structures.

Trace the flow of cerebrospinal fluid.

Apply the diagnostic significance of ventricular function to clinical practice in speech-language pathology

The CEREBROSPINAL FLUID (CSF) is a clear fluid which circulates in and around the entire CNS. The average adult volume is about 135 ml, and it is totally replaced every 6 hours. It is composed of small quantities of inorganic salts and some proteins:

potassium chloride

sodium chloride

albumen

dextrose

Cerebrospinal fluid is formed in the ventricles and circulates inside and outside the CNS. It is formed in the spaces called VENTRICLES. (You should look up VENTRICLE in Mosby's).

The general plan of the ventricular system is of two LATERAL VENTRICLES, one in each hemisphere (telencephalon), connected to a median and caudal THIRD VENTRICLE forming the cavity of the diencephalon and a further caudal FOURTH VENTRICLE, forming the cavity of the mesencephalon.

For Fun: Da Vinci's identification of the ventricles

The Cerebral Ventricular System

Most of the CSF is formed in the Choroid Plexuses of the ventricles.

From the two lateral ventricles, CSF flows through the interventricular foramina to the third ventricle. Then it flows through the cerebral aqueduct to the fourth ventricle from whence it flows into the subarachnoid space via the lateral foramina (of Lushka) and the median foramen (of Magendie).

Blockage of the ventricular system can lead to distention and damaging pressure to adjacent CNS structures: internal hydrocephalus.

A Hydrocephalus Fact Sheet

Examinations of the positions of the ventricles is important diagnostic information, whether through ventriculography or imaging scan.

Fluid flows over the outside of the CNS in the subarachnoid space, finally reaching the upper surfaces of the cerebral hemispheres. Here, it is absorbed into the venous blood stream through villi in the arachnoid mater.

More Information on Cerebrospinal Fluid

CSF plays several roles.

It protects the CNS from shock.

It balances pressure changes brought about by changes in blood volume and postural changes.

It functions like lymph.

For an overview of cerebrospinal fluid and the ventricles with illustrations, please open the link below.

The Ventricular System and CSF

Once you have finished you should:

Go on to Online Lesson 2
or
Go back to Central Nervous System Part II

E-mail Bill Culbertson at bill.culbertson@nau.edu
Call Bill Culbertson at (520) 523-7440