Cerebral Aqueduct






CEREBRAL AQUEDUCT

The cerebral aqueduct is a narrow opening in the brain that connects the third ventricle with the fourth ventricle, allowing cerebrospinal fluid to flow between these two areas. Ventricles are openings in the brain that provide a pathway for cerebrospinal fluid. Cerebrospinal fluid is the cushiony fluid that protects the brain and spine from trauma. The cerebral aqueduct drains cerebrospinal fluid from the third ventricle to the fourth ventricle.

The third ventricle is a narrow, four-sided, irregularly shaped opening in the middle of the brain. The fourth ventricle is a wide, flat open space located in the back bottom part of the brain. The third ventricle, fourth ventricle, and cerebral aqueduct are pictured below.

WHAT DOES THE CEREBRAL AQUEDUCT LOOK LIKE?

Below is a picture of the cerebral aqueduct and the ventricles in the brain:
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WHAT ARE SOME OTHER DETAILS ABOUT THE CEREBRAL AQUEDUCT?

The cerebral aqueduct is about 3/4 of an inch long and is lined with ependyma. Ependyma is a type of membrane that lines the ventricles of the brain. A membrane is a thin layer of flexible tissue that covers something. The cerebral aqueduct can be found in the midbrain. The midbrain is the top part of the brainstem. The brainstem is an area in the lower part of the brain that connects it with the spinal cord. Below is a picture of the midbrain and the rest of the brainstem (pons and medulla).

The cerebral aqueduct is the only major part of the ventricle system that does not contain a choroid plexus. The choroid plexus is a cluster of blood vessels that lines the ventricles and produce cerebrospinal fluid.
WHAT HAPPENS IF THE CEREBRAL AQUEDUCT BECOMES BLOCKED?

The cerebral aqueduct can become blocked. This leads to an abnormal increase in cerebrospinal fluid in the brain and enlargement of the ventricles, a condition known as hydrocephalus. Cerebrospinal fluid is the cushiony fluid that protects the brain and spine from trauma. The cerebrospinal fluid builds up when there is a blockage because there is no place for it to go, much like the buildup of fluid that occurs when a pipe in the sink becomes clogged. The ventricles become larger because the increased fluid (which has no place to go) builds up and expands outwards.

In the case of a blockage of the cerebral aqueduct, cerebrospinal fluid from the lateral (side) ventricles and the third ventricle cannot get down to the fourth ventricle. The lateral ventricles are two curved openings (shaped like a horseshoe) located deep within the top section of the brain. There is one lateral ventricle on each side of the brain. See above for a picture of the lateral ventricles.
WHAT ELSE IS THE CEREBRAL AQUEDUCT KNOWN AS?

The lateral ventricle is also known as the aqueduct of sylvius, aqueductus sylvii, sylvian aqueduct, aqueductus mesencephali, aqueductus cerebri, aqueduct of cerebrum, and iter a tertio ad quartum ventriculum.

WHAT IS THE ORIGIN OF THE TERM, CEREBRAL AQUEDUCT?

Cerebral aqueduct comes from the Latin word "cerebrum" meaning "brain" and the Latin word "aqueductus" meaning "water canal." Put the words together and you have "brain water canal."