Anatomy and White Matter Connections of the Superior Frontal Gyrus

The superior frontal gyrus (SFG) is an important region implicated in a variety of tasks including motor movement, working memory, resting-state, and cognitive control. A detailed understanding of the subcortical white matter of the SFG could improve postoperative morbidity related to surgery around this gyrus. Through DSI-based fiber tractography validated by gross anatomical dissection, we characterized the fiber tracts of the SFG based on their relationships to other well-known neuroanatomic structures. Diffusion imaging from the Human Connectome Project from 10 healthy adult subjects was used for fiber tractography. We evaluated the SFG as a whole based on its connectivity with other regions. All tracts were mapped in both hemispheres, and a lateralization index was calculated based on resultant tract volumes. Ten cadaveric dissections were then performed using a modified Klingler technique to delineate the location of major tracts integrated within the SFG. We identified four major SFG connections: the frontal aslant tract connecting to the inferior frontal gyrus; the inferior fronto-occipital fasciculus connecting to the cuneus, lingual gyrus, and superior parietal lobule; the cingulum connecting to the precuneus and parahippocampal gyrus/uncus; and a callosal fiber bundle connecting the SFG bilaterally. The functional networks of the SFG involve a complex series of white matter tracts integrated within the gyrus, including the FAT, IFOF, cingulum, and callosal fibers. Postsurgical outcomes related to this region may be better understood in the context of the fiber-bundle anatomy highlighted in this study. Clin. Anat. 33:823-832, 2020. (c) 2019 Wiley Periodicals, Inc.