The temporal stem constitutes a white matter connective pathway between the anterior temporal lobe, frontal lobe, and diencephalon. Although inconsistent in literature, it is thought to be comprised of six tracts. Comprehension of the structure of the temporal stem will allow for more profound anatomical and functional studies, as well as intraoperative preservation of these tracts. Using diffusion tensor tractography, we have dissected twenty brains from the Human Connectome Project dataset, and performed analysis on the volume, morphological and topographic anatomy of the various fasciculi. Our analysis showed that the inferior fronto-occipital fascicle represents the most voluminous tract of the temporal stem, with a mean of 32.7% and 35.2% in the left and right hemispheres respectively, followed by the inferior longitudinal fascicle. In the left hemisphere, the optic radiation and uncinate fascicle succeed in order of volume, whereas in the right, the third most voluminous tract is the uncinate fascicle with a mean volume of 16.75%, followed by the optic radiation (14.1%). The least voluminous tracts in both hemispheres are the anterior commissure (4.95% and 4.2%) and inferior thalamic tract (2.7% and 1.8%). The most anterior extent of the Meyer’s loop reaches the transition of amygdala/head of hippocampus in only 40% of the optic radiation, most frequently on the left side. This work represents a comprehensive three-dimensional descriptive synthesis of the white matter tracts of the temporal stem, integrating existing anatomical knowledge into a reproducible spatial framework. By combining systematic methodology with illustrative visualization, this approach facilitates a clear understanding of these important structures, helping in educational contexts and intraoperative planning.
Ramos et al. (Wed,) studied this question.