Human anatomy, including structure and development and practical considerations . reater part of the hemispherical space, but from actual entrance into which it is now, as well assuljsequently, separated l)y the attenuated invaginated wall of the iiallium. This displacedwall, with the enclosed pial tissue, afterward becomes the choroid i)lexus of the lateralventricle and is carried downward along the mesial surface of the inferior horn with the for-mation of the temporal lobe. Where the mesoblastic sheet overlies the roc^f of the fore-brainit becomes the velum interpositum, which, it is eviden
Human anatomy, including structure and development and practical considerations . reater part of the hemispherical space, but from actual entrance into which it is now, as well assuljsequently, separated l)y the attenuated invaginated wall of the iiallium. This displacedwall, with the enclosed pial tissue, afterward becomes the choroid i)lexus of the lateralventricle and is carried downward along the mesial surface of the inferior horn with the for-mation of the temporal lobe. Where the mesoblastic sheet overlies the roc^f of the fore-brainit becomes the velum interpositum, which, it is evident, is continuous on each side with thechoroid Since the choroidal fissure begins in front at a point which later overlies theforamen of Monro and, further, since the choroid plexuses of the two sides are connected by Fig. io-?i. Choroidal fissur artery ralliiim Lamina ttrniiiialis Corpus .striatumHypothalamic region Khiuencephalon Optic recess Optic chiasmInfundibular recess Mammillary bod> Pontine flexure Spinal cord Rof)f of Ihird ventricle Ilahi-iiula. Mid-brain avity of niid-hralnIsthmus Cerebelhini PonsFloor of IV ventricleMedulla (.crvical flexure Reconstruction of brain of human frrttis of 3 months (50 mm.) ; mesial surface. X »,%? Drawn from His model. the intervening velum interpositum, it follows that the plexuses converge towards and meetover \\\tt foramina—a relation which they retain in the adult brain. The backward expansionof the hemispheres is accompanied by a corresponding backward prolongation of the youngpia mater covering the roof of the diencephaion, later the third ventricle. After the corpuscallosum and the fornix have been superimposed, the impression is given from the relation ofthe structures, as seen in the completed brain, that the pia has gained its position over theroof of the third ventricle by growing forward beneath the si)lenium and fornix. That such,however, is not the case is evident from the developmental history of
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Keywords: ., bookauthormc, bookcentury1900, bookdecade1910, booksubjectanatomy
