Definition of Aqueduct of the midbrain
Aqueduct of the midbrain: A canal that communicates between the third and fourth ventricles in a system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord.
The four ventricles consist of the two lateral ventricles, the third ventricle and the fourth ventricle:
- Lateral ventricles: The lateral ventricles are in the
cerebral hemispheres. Each lateral ventricle consists of a triangular central
body and four horns. The lateral ventricles communicate with the third
ventricle through what is called the interventricular foramen (opening).
- The third ventricle is a median (midline) cavity in
the brain that is bounded by the thalamus and hypothalamus on either side.
Anteriorly (in front) the third ventricle communicates with the lateral
ventricles and posteriorly (in back) the third ventricle communicates with the
aqueduct of the midbrain (also called the aqueduct of Sylvius).
- The fourth ventricle is the most inferior (lowest) of the four ventricles of the brain. It extends from the aqueduct of the midbrain to the central canal of the upper end of the spinal cord with which it communicates by the two foramina (openings) of Luschka and the foramen (opening) of Magendie.
The ventricles are filled with cerebrospinal fluid, which is formed by structures called choroid plexuses located in the walls and roofs of the ventricles.
Last Editorial Review: 8/28/2013
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