Research On Frontal Cortex Of Human Brian Morphologically

OBJECTIVE:To deeply understand the morphology of frontal lobe gyrus and provide detailed data for clinical application;to explore the evaluation index for morphological difference in cerebral hemisphere and provide morphological data for comparison between different cerebral hemispheres or the cerebral hemisphere functions of different individuals.METHODS:35 adult formalin fixed brains(25 males,10 females)were taken for the following using: First, to photo every brain from the anterior, posterior, superior, inferior and lateral sides with digital camera, and stored in computer for future reference. The form of gyri could be classified as rectilinear figure, bend-shaped, turned-shaped, crumb-shaped, and island ring-shaped; and tedious degrees could be classified as 1st, 2nd, 3rd, 4th, 5th. With these quantitative indexes, observed and judged every frontal lobe gyrus, then matched grade correlation analysis was made. At the same time, observed the size proportion, location and arrangement of gyri in frontal lobe, and integral form of frontal lobes. Second, continuously photo lateral surface of cerebral hemisphere every 9 degrees from front to rear with designed shooting frame. All these photos were integrated into one plane outspread drawing. Observed and measured the area of frontal lobe, gyrus morphology, the starting point, stop point and branches of sulcus. Paired T test were made for data.RESULTS: In integral form, precentral gyrus presented upper and lower trend, upper-smaller and lower-larger or upper-retroposition and lower-protrusion. Disconnection was found in the middle-lower 1/3 sometimes, the front edge of the upper end, the middle and the lower end joined with superior frontal gyrus, middle frontal gyrus and inferior fontal gyrus respectively. Superior frontal gyrus presented pre and post trend, pre-smaller and post–larger, its shape were ladder, triangle, or long strip. The morphological changes of middle frontal gyrus was obvious: one or two bending gyrus; had or had not anterior half segment; the back-end started at the middle part or the middle-lower part of precentral gyrus or the branch of inferior fontal gyrus; the front-end joined with superior frontal gyrus and inferior fontal gyrus or only inferior fontal gyrus. The middle part buckled, folded and surrounded to island, or had branch to superior frontal gyrus. Inferior fontal gyrus was made of concurrent gyrus with upper and lower trend, it had ladder or triangle shape. The gyrus of prefrontal area (nearby the frontal pole) was internal and external trend, there were several transverse gyrus in specimens which had not anterior half segment in middle frontal gyrus. Besides, there were some parallel gyrus in front of precentral gyrus, we named them the accessory gyrus of precentral gyrus. In form classification, precentral gyrus was grade 2 or grade 3, superior frontal gyrus was grade 3, middle frontal gyrus and inferior fontal gyrus were grade 5. Observed in plane outspread drawing, the gyrus morphology between left and right cerebral hemispheres were different, including the cortical area of the lateral surface of frontal lobe and the cortical area of superior frontal gyrus and inferior fontal gyrus(P≤0.01). More than 75% of superior frontal sulcuses origined from precentral sulcus, and most of them had one segment or two segments, less than 17% had three segments. More than 50% of superior frontal sulcuses terminated in frontal pole, less than 25% terminated in one third of anterior frontal lobe; More than 65% of inferior frontal sulcus origined from one third of inferior precentral sulcus and one third of anterior precentral gyrus. 43% terminated in one third of anterior frontal lobe in left hemi-sphere, (46% in right hemisphere).CONCLUSIONS: 1. morphology of gyrus could be used as one index for comparing the brain difference, comparing the cerebral hemispheres difference can be done by the classification of gyrus morphology. precentral gyrus and superior frontal gyrus is independent, lower classification, middle and inferior fontal gyrus often are staggered appear, have more forms, higher classification.2. Besides classical form, other forms can be found in frontal lobe. The forms of superior, nferior frontal gyri, frontal lobe and outer structures of cranium can be changed by middle frontal gyrus 3. The morphology and cortical area of the frontal lobe were significantly different between left hemisphere and right hemisphere.