The ventricles are cavities filled with spinal fluid located several centimeters deep to the cerebral cortex. Normal spinal fluid is as clear as water and similar in compositiion to serum (a filtrate of blood without blood cells or large protein molecules). Spinal fluid is the fltrate resulting from the migration of blood from the capillaries of the chroid plexus and the ventricular cavity.
The walls of the ventricular cavities are carpeted by a single layer of ependymal cells.
There are right and left lateral venticles. The anterior horn of the lateral ventricle is the farthest forward part of the ventricular system and the part most accessible to a ventricular catheter placed into the the brain through an entry point in line with the pupil at the coronal suture.
atrium
The third venticle is located between the right and left thalamus.
The "fourth" ventricle is located between the pons (in front) and cerebellum (behind). On a sagittal view it appears triangular (with a peak up into the cerebellum). On the axial view it us usually small and oval. (Enlargement of the fourth ventricle indicates that there is blockage of cerebrospinal flow at the Foramina (openings) that drain the fourth ventricle or father distal (i.e. at the arachnoid granulations) in the cerebrospinal fluid drainage system. Diseases that can cause enlargement of the fourth ventricle by blocking flow out of the Foramina of Lushka and Magendie include: meningitis of the base of the brain [tuberculosis most common cause], carcinomatous (cancer-related) meningitis, and subarachnoid hemorrhage.
A lesion (such as cerebellar tumor or cysticercosis cyst) that grows large enough in the fourth ventricle can block flow into and through the ventricle causing a so-called "non-communicating" hydrocephalus.
Aqueduct of Sylvius
The Aqueduct of Sylvius is a narrow channel in the midbrain through which cerebrospinal fluid flows from the third into the fourth ventricle.
Foramen of Monro
The Foramen of Monro is a small opening between the lateral and third ventricles.
Foramen of Lushka
The Foramen of Lushka is an opening in the wall of the lower fourth ventricle through which cerebrospinal fluid flows into the cisterna magna (space around lower brainstem and upper spinal cord).
Foramen of Magendie
| LATERAL | LATERAL | |||||
| foramen Monro | THIRD | foramen Monro | ||||
| A* | ||||||
| FOURTH | ||||||
| foramen Lushka | foramen Magendie | foramen Lushka | ||||
 |
| Lateral ventricles in hemispheres
on either side of the corpus callosum.
Gregory Pinsky MD USC Neuropathology
|
| Lateral ventricles |
| Third ventricle |
| Fourth ventricle |
Ventriculomegaly: larger-than-normal ventricles. Hydrocephalus is a pathologic condition associated with ventriculomegaly.
