. Anatomy, descriptive and applied. Anatomy. PARTS DERIVED FROM THE FORE-BRAIN 903 ventricular surface is largely free, except for an area, of variable size, by which the two thalami are fused in 90 per cent, of brains. The thalamic fusion is also called the middle commissure or medicommissure. The free surface is co\'ered by ependyma and is of smooth contour. Its dorsal limit is marked by an ependymal ridge, usually torn through in dissection, the taenia thalami or ripa,' fortified by a subjacent narrow band of fibres called the stria meduUaris, which may be traced to the habenular nucleus an
. Anatomy, descriptive and applied. Anatomy. PARTS DERIVED FROM THE FORE-BRAIN 903 ventricular surface is largely free, except for an area, of variable size, by which the two thalami are fused in 90 per cent, of brains. The thalamic fusion is also called the middle commissure or medicommissure. The free surface is co\'ered by ependyma and is of smooth contour. Its dorsal limit is marked by an ependymal ridge, usually torn through in dissection, the taenia thalami or ripa,' fortified by a subjacent narrow band of fibres called the stria meduUaris, which may be traced to the habenular nucleus and habenular commissure (or "stalk" of the pineal body). Caudad lies a depressed triangular area—the trigonum habenulae, situated cephalad of the superior cjuadrigeminal body. The dorsal surface is usually described as being free, but only a narrow ectal portion can be so described, the ependyma of the lateral ventricle being slightly rORAMEN OF MONRO LE COMMISSURE HOROIO PLEXUS OF HIHD VENTRICLE. l/ENTRICLE Fig. 668.—Mesal aspect of a brain sectioned in the median sagittal plane. reflected upon it (the lamina affixa) before entering into the formation of the choroid plexus of the lateral ventricle. The rest of the dorsal surface is not lined by ependyma, but is in contact with the pial fold called the velum interpositum. This surface is of a whitish color owing to a thin layer, of white fibres, the stratum zonale. A faint oblique groove crosses this surface in a caudolateral direction, corresponding to the ectal edge of the fornix. Laterad it is demarcated from the caudate nucleus by a groove which is occupied by the striatal vein and a slender band of fibres, called the taenia semicircularis or stria terminalis. The surface is not of e^en contour throughout, usually showing three eminences (in addition to the puh'inar) corresponding to the main nuclear aggregations within the thal- amus—viz.: Tuberculum anterius, mediahs, and lateralis. 3 formed by tiie rupture
Size: 1889px × 1322px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
