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Third ventricle
From Wikipedia, the free encyclopedia
The third ventricle (ventriculus tertius) is one of four connected fluid-filled cavities within the human brain. It is a median cleft between the two thalami, and is filled with cerebrospinal fluid (CSF).
It is in the midline, between the left and right lateral ventricles. It communicates with the lateral ventricles anteriorly by the interventricular foramina (by Atif) , and with the fourth ventricle by the mesencephalic duct (aqueduct of Sylvius) posteriorly.
Developmentally it represents the cavity of the diencephalon, though they are in front of the interventricular foramen which is derived from the median part of the telencephalon. The third ventricle is bounded by the thalamus and hypothalamus on both the left and right sides. The lamina terminalis forms the anterior wall of the third ventricle.
There are two protrusions on the front of the third ventricle, the supra-optic recess (above the optic chiasma), and the infundibular recess (above the pituitary stalk). In casts of the ventricular system, a small 'hole' may be seen in the body of the third ventricle. This is formed where the two thalami are joined together at the interthalamic adhesion (not seen in all people).
The four fluid-filled cavities in the brain, collectively (with interventricular foramina and mesencephalic duct) the ventricular system, are the left and right lateral ventricles, the third ventricle, and the fourth ventricle.
 Coronal section of brain immediately in front of pons. |
 Coronal section of brain through intermediate mass of third ventricle. |
 Drawing of a cast of the ventricular cavities, viewed from above. |
 Coronal section of brain through anterior commissure. |
 Diagram showing the positions of the three principal subarachnoid cisternæ. |
 Median sagittal through the hypophysis of an adult monkey. Semidiagrammatic. |
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| Epithalamus | Pineal body, Habenula, Habenular nuclei |
| Hypothalamus | anterior: Anterior hypothalamic nucleus, Paraventricular nucleus, Preoptic area, Supraoptic nucleus, Suprachiasmatic nucleus intermediate/middle/tuberal/pituitary: infundibulum, median eminence, arcuate nucleus, Ventromedial nucleus, Dorsomedial hypothalamic nucleus, Tuber cinereum, Pituitary gland (Anterior pituitary, Posterior pituitary) posterior/lateral: posterior nucleus, Mammillary body, Lateral nucleus |
| Subthalamus | Subthalamic nucleus, Zona incerta |
| Thalamus | Pulvinar, Metathalamus (Medial geniculate nucleus, Lateral geniculate nucleus), list of thalamic nuclei |
| Other | Third ventricle, Interventricular foramina, Optic chiasm, Subfornical organ |