Table 2.

Morphological variability in humans

StructureMorphologyLeft hemisphereRight hemisphereTotal
ipcsOne segment100% (30)(90%) 2795% (57)
Two segments010% (3)5% (3)
Three segments000
ifsOne segment56.7% (17)63.3% (19)60% (36)
Two segments43.3% (13)36.6% (11)40% (24)
Three segments000
arVertical83.3% (25)80% (24)81.7% (49)
Oblique6.7% (2)10% (3)8.3% (5)
Diagonal(10%) 310% (3)10% (6)
dsNot present30% (9)16.7% (5)23.3% (14)
No connection26.7% (8)33.3% (10)30% (18)
Connection43.3% (13)50% (15)46.7% (28)
  • ar, Anterior ascending ramus of the Sylvian fissure; ds, diagonal sulcus; ifs, inferior frontal sulcus; ipcs, inferior precentral sulcus. An oblique as is one that is neither vertical or diagonal and tends to curl in different directions through parasagittal sections. Some diagonal ar may become more vertical medially (supplemental Appendix, available at www.jneurosci.org as supplemental material). The ds may be connected to one or a combination of the ar, ifs, or ipcs. For an individual breakdown of values, see supplemental material (available at www.jneurosci.org).