The Inter Brain
Inter brain (thalamencephalon) is the region of the third ventricle, and comprises the parts developed from the second cerebral vesicle, together with that position of the first vesicle which is not concerned in the formation of the cerebral hemispheres.
The inter brain is connected above and in front with the cerebral hemispheres; behind, with the nid-brain or mesencephalon. On its upper surface it is entirely concealed from view, as it is covered by those portion of the internal surface of the cerebral hemispheres which have fused together to form the corpus callosum and the formix, and is separated from the latter by the two layers of pia meter which form the velum interposition. Inferiority it reaches the base of the brain, forming the structures contained in the interpeduncular space.
The third ventricle is the cavity of the inter-brain. It is a narrow median crevice between the two optic thalami, which constitute the side walls of the inter-brain. Its roof is formed by the velum interpositum, from which are suspended the choroids plexuses of the third ventricle. Its floor somewhat oblique in its direction, is formed, from before backward, by the tuber cinereum, with its infundibulum and pituitary body; the corpora albieantia; the posterior perforated space; and the tegmenta of the crura cerebrum. Its sides are formed by the optic thalami, and are limited above by delicate band of white fibers, the atria pinealis, which runs along the junction of the mesial and upper surfaces of the optic thalamus to joint the anterior pillars of the fornix.
The middle or soft commissure consist almost entirely of gray matter. It connects or link the two optic thalami, and is continuous with the gray mater lining the anterior part of the third ventricle. It is frequently broken in examining the brain, and might then be supposed to be wanting, it is sometimes double.
The inter brain is connected above and in front with the cerebral hemispheres; behind, with the nid-brain or mesencephalon. On its upper surface it is entirely concealed from view, as it is covered by those portion of the internal surface of the cerebral hemispheres which have fused together to form the corpus callosum and the formix, and is separated from the latter by the two layers of pia meter which form the velum interposition. Inferiority it reaches the base of the brain, forming the structures contained in the interpeduncular space.
The third ventricle is the cavity of the inter-brain. It is a narrow median crevice between the two optic thalami, which constitute the side walls of the inter-brain. Its roof is formed by the velum interpositum, from which are suspended the choroids plexuses of the third ventricle. Its floor somewhat oblique in its direction, is formed, from before backward, by the tuber cinereum, with its infundibulum and pituitary body; the corpora albieantia; the posterior perforated space; and the tegmenta of the crura cerebrum. Its sides are formed by the optic thalami, and are limited above by delicate band of white fibers, the atria pinealis, which runs along the junction of the mesial and upper surfaces of the optic thalamus to joint the anterior pillars of the fornix.
The middle or soft commissure consist almost entirely of gray matter. It connects or link the two optic thalami, and is continuous with the gray mater lining the anterior part of the third ventricle. It is frequently broken in examining the brain, and might then be supposed to be wanting, it is sometimes double.
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