Ventricles & CSF

2. VENTRICLES
 The brain has hollow fluid-filled cavities called ventricles.
 Inside the ventricles, there is a ribbon-like structure called the choroid
plexus that makes clear colorless cerebrospinal fluid (CSF).
 The ventricular system is a set of four interconnected cavities
(ventricles) in the brain, where the cerebrospinal fluid (CSF) is
produced.
 The system comprises four ventricles:
Lateral ventricles right and left (one for each hemisphere)
Third ventricle
Fourth ventricle

3. The Human four ventricles and
connections.
 Blue - Lateral ventricles
 Cyan - Interventricular foramina
(Monro)
 Yellow - Third ventricle
 Red - Aqueaductus mesencephali
(aqueduct of Sylvius)
 Purple - fourth ventricle
 Green - continuous with the
en:central canal

5.  There are two ventricles deep within the cerebral hemispheres called
the lateral ventricles.
 They both connect with the third ventricle through a separate opening
called the foramen of Monro.
 The third ventricle connects with the fourth ventricle through a long
narrow tube called the aqueduct of Sylvius.
 From the fourth ventricle, CSF flows into the subarachnoid space
where it bathes and cushions the brain.
 CSF is recycled (or absorbed) by special structures in the superior
sagittal sinus called arachnoid villi.
 A balance is maintained between the amount of CSF that is absorbed
and the amount that is produced. A disruption or blockage in the
system can cause a build up of CSF, which can cause enlargement of
the ventricles (hydrocephalus) or cause a collection of fluid in the
spinal cord (syringomyelia).

6.  There are several foramina, openings acting as channels, that connect the
ventricles. Since they are connected, they are called as interventricular
foramina. The interventricular foramina (also called the foramina of monro)
connect the lateral ventricles to the third ventricle through which the
cerebrospinal fluid can flow.
Name From To
Interventricular
foramina (Monro)
lateral ventricles third ventricle
Cerebral aqueduct
(Sylvius)
third ventricle fourth ventricle
Median aperture
(Magendie)
fourth ventricle
subarachnoid space
via the cisterna magna
Right and left lateral
aperture (Luschka)
fourth ventricle
subarachnoid space
via the cistern of great
cerebral vein

7. LOCATION
 The four cavities of the human brain are called ventricles.
 The two largest are the lateral ventricles in the cerebrum
 The third ventricle is in the diencephalon of the forebrain between the
right and left thalamus
 And the fourth ventricle is located at the back of the pons and upper
half of the medulla oblongata of the hindbrain.
 The ventricles are concerned with the production and circulation of
cerebrospinal fluid.

10. CEREBROSPINAL FLUID
 CSF flows within and around the brain and spinal cord to help cushion
it from injury. This circulating fluid is constantly being absorbed and
replenished.

11. PRODUCTION & FLOW
 CSF is produced by modified ependymal cells of the choroid plexus
found in all components of the ventricular system except for the
cerebral aqueduct and the posterior and anterior horns of the lateral
ventricles.
 CSF flows from the lateral ventricles via the interventricular foramina
into the third ventricle, and then the fourth ventricle via the cerebral
aqueduct in the brainstem. From the fourth ventricle it can pass into
the central canal of the spinal cord or into the subarachnoid cisterns
via three small foramina: the central median aperture and the two
lateral apertures.

12.  The fluid then flows around the superior sagittal sinus to be
reabsorbed via the arachnoid granulations (or arachnoid villi) into the
venous sinuses, after which it passes through the jugular vein and
major venous system.
 CSF within the spinal cord can flow all the way down to the lumbar
cistern at the end of the cord around the cauda equina where lumbar
punctures are performed.
 The cerebral aqueduct between the third and fourth ventricles is very
small, as are the foramina, which means that they can be easily
blocked.

13. CAUDA EQUINA