Human anatomy, including structure and development and practical considerations . Left hemisphere of brain of five monthsfiLlus ; three-fourths natural size. Inferior fronta terparietal of the jiarieto-frontal andthe orl)ital opercula. Theorbital and particularly thefrontal operculum are latein their differentiation andgrowth, and not untiltowards the second yearafter birth do they comeinto apposition with eachother and the remainingopercula to complete thecurtain that overhangs theinsula. Along with theclosure of the front part ofthe Sylvian fossa, the dif-ferentiation of the anteriorlimbs of
Human anatomy, including structure and development and practical considerations . Left hemisphere of brain of five monthsfiLlus ; three-fourths natural size. Inferior fronta terparietal of the jiarieto-frontal andthe orl)ital opercula. Theorbital and particularly thefrontal operculum are latein their differentiation andgrowth, and not untiltowards the second yearafter birth do they comeinto apposition with eachother and the remainingopercula to complete thecurtain that overhangs theinsula. Along with theclosure of the front part ofthe Sylvian fossa, the dif-ferentiation of the anteriorlimbs of the fissure pro-gresses, since upon theadequate growth of the frontal operculum depends the production of a distinct pars triangularisand of two separate anterior branches. Faulty development of this intermediate part of theopercular wall accounts for the Y or I form, as well as the occasional absence, of the anterior Orbitaloperculum Olfactory bulb Insula Sylvian fissure Superior temporal sulcus Lateral surface of left hemisphere of eight months foetus ; insula is partly coveredby opercula; three-fourths natural size. {Retzius.) The central fissure (sulcus centralis), or fissure of Rolando, extendstransversely across the upper half of the convex dorsal surface of the hemisphere andtherefore, with the bordering precentral and postcentral convolutions, interrupts thegeneral longitudinal course of the gyri and sulci. Bearing this peculiarity in mind,the fissure is readily identified even in brains exhibiting an elaborate and complexmodelling. It begins above on the supero-mesial margin of the hemisphere, a shortdistance behind the middle of the border, and descends with a slight general forwardobliquity to the vicinity of the posterior limit of the fissure of Sylvius, above whosemid-point it usually ends. Its upper extremity usually extends over the supero-mesial border of the hemisphere and, passing
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Keywords: ., bookauthormc, bookcentury1900, bookdecade1910, booksubjectanatomy
