Structural and functional anatomy of the superior longitudinal fasciculus: a historical and contemporary narrative review.

Abstract

The superior longitudinal fasciculus (SLF) is one of the major associative white matter pathways of the human brain, connecting frontal regions with parietal, temporal, and occipital cortices. Despite its central role in cognition, language, and motor functions, its structural organization and functional significance remain subjects of ongoing debate. This narrative review synthesizes historical ex vivo studies and contemporary in vivo neuroimaging data to clarify converging and conflicting descriptions of the SLF. We trace the evolution of anatomical concepts from classical dissection and histological staining to modern diffusion MRI and tractography, highlighting how methodological advances have reshaped our understanding of SLF subcomponents. Particular attention is given to the distinction between the SLF, the arcuate fasciculus, and the cingulum, which we argue reflects differing classificatory conventions and methodological choices as much as underlying anatomy, and to the nomenclatural issues addressed by the Terminologia Neuroanatomica. Functional correlates related to language, motor control, and higher cognitive processes are discussed, alongside clinical implications for neurology, psychiatry, and neurosurgery. Finally, we consider pedagogical and epistemological challenges posed by the variability of white matter anatomy and by the dependence of neuroanatomical knowledge on investigative tools.