FIGURE 1-28

     Anteriorly, the lateral fissure separates the temporal lobe from the frontal and parietal lobes; posteriorly, the line separating the temporal and parietal lobes is a somewhat arbitrary extension of the lateral fissure. Because of their unique geometry the insula and the limbic "lobe" to not fit into the four lobe scheme. As the name suggests, the insula is indeed an island of cortex that has been buried by the expanding frontal, parietal and temporal lobes; it shares borders with all three. The limbic "lobe" runs around the medial edge of the hemisphere, sharing borders with all four lobes. Because of its functional importance it is commonly called a lobe, though it hardly seems like one.