Fissures of the frontal operculum in as a South African sample

[摘要] This study primarily seeks to confirm two systems of classifying the sulci of the frontaloperculum1 (F3): the radiologically derived system of Ebeling et al (1989) involving fourTypes of Sulcal Connections, and the anatomical classification of the anterior rami of thelateral fissure, involving three patterns. Sulcal- and intersulcal- lengths are also considered.The sample consisted of 220 cadaveric hemispheres; 65 of which were whole brains(control category); and 90 consisting of equal numbers of separate right- and lefthemispheres(case category). Specimens were orientated by examining relevant features of:the lateral fissure; the postcentral sulcus; and the central fissure. Features of the remainingboundary sulci (precentral sulcus / sulci, and inferior frontal sulcus) of F3 were alsoconsidered. The focus was on examining the: frequency of occurrence, shape, andconnections of the sulci of the F3. The sulci of F3 were designated as: major sulci [anteriorascending (AAR)- and anterior horizontal (AHR)- rami, and stem of the anterior rami whenpresent); and accessory sulci (sulci of the –pars opercularis and –pars triangularis). Sulcallengths were measured using thread, with needles as anchors. Intersulcal lengths wererecorded as straight-line distances between parallel pins inserted into the sulci of thefrontoparietal operculum. Specimens fixed outside the cranial cavity were excluded frommeasurement. The reliability of the data was monitored, by repeating the observations.The two systems of classification were broadly confirmed. The criteria for the Types ofSulcal Connections were modified in view of the findings on double precentral sulci andthe connections of the opercular sulcus (which occurred as either one or as two sulci). Asulcus of the pars triangularis (which occurred as either one, two, or as three sulci) wasfound to be a useful landmark. The Chi-square test was applied to the data in the twosystems of classification. There were no significant interhemispheric differences withrespect to the incidences of: Types 1-4 of Sulcal Connections, or Patterns of the AnteriorRami (I, Y, and VU). Sulcal lengths were similar to that reported by Ono et al (1990). TheStudent t-test was applied to sample sizes 18 and above. No significant interhemisphericdifferences, in the lengths of the sulci that were considered, were found. A significant1 The definition of the frontal operculum as the inferior frontal gyrus only, is used for the purposes ofthis study. The frontal operculum may also be abbreviated as F3.vdifference was found in two instances when comparing the case- and control- categories.Intersulcal distances are reported on in the frontal- and frontoparietal- operculum.

[发布机构] University of the Witwatersrand