. Bensley's Practical anatomy of the rabbit : an elementary laboratory text-book in mammalian anatomy. Rabbits -- Anatomy. THE FOREBRAIN 351 (e) The pineal body (corpus pineale) is a small, somewhat conical structure lying between the dorsal posterior tips of the cerebral hemispheres (cf. p. 134). It is connected by a hollow stalk with the unpaired portion of the brain (the diencephalon) lying below it. The connection is concealed by a mass of pigmented vascular tissue, the beginning of the chorioid plexus of the third ventricle, and usually also by a small portion of the dura mater containing
. Bensley's Practical anatomy of the rabbit : an elementary laboratory text-book in mammalian anatomy. Rabbits -- Anatomy. THE FOREBRAIN 351 (e) The pineal body (corpus pineale) is a small, somewhat conical structure lying between the dorsal posterior tips of the cerebral hemispheres (cf. p. 134). It is connected by a hollow stalk with the unpaired portion of the brain (the diencephalon) lying below it. The connection is concealed by a mass of pigmented vascular tissue, the beginning of the chorioid plexus of the third ventricle, and usually also by a small portion of the dura mater containing part of the sagittal venous sinus. The latter may be carefully de- tached. By raising and pressing apart the tips of the hemispheres and pulling away the pineal body with the tissue to which it is attached, the dorsal surface of the diencephalon will be sufficiently exposed to make out the following features: (/) The slit-like aperture appearing in the middle line after the removal of the pineal body represents the dorsal por- tion of the third ventricle (ventriculus tertius) (Fig. 116), the roof of which is formed by tissue just torn away with the pineal body. This roof consists of a thin membrane over which lies a dense network of fine blood vessels con- tained in pia mater, the chorioid plexus. Folds of the membrane and plexus dip down into the ventricular cavity and here cerebrospinal fluid is se- creted. (g) The lateral margins of the aper- ture are largely formed by mi- nute spindle-shaped masses, one. on either side, the habenulae. Their posterior ends are united by a slender transverse band, the habenular commissure (commissura habenularum). The fibres constituting this band are faintly traceable forward, where they form a pair of thin whitish filaments (medullary. Fig. 116. Diagram, showing the arrangement of the parts of the thalamencephalon as viewed from the dorsal surface, after removal of the pineal body: a., anterior thalamic tubercle; , habenular commissiur
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