Table 2.
Morphological variability in humans
| Structure | Morphology | Left hemisphere | Right hemisphere | Total |
|---|---|---|---|---|
| ipcs | One segment | 100% (30) | (90%) 27 | 95% (57) |
| Two segments | 0 | 10% (3) | 5% (3) | |
| Three segments | 0 | 0 | 0 | |
| ifs | One segment | 56.7% (17) | 63.3% (19) | 60% (36) |
| Two segments | 43.3% (13) | 36.6% (11) | 40% (24) | |
| Three segments | 0 | 0 | 0 | |
| ar | Vertical | 83.3% (25) | 80% (24) | 81.7% (49) |
| Oblique | 6.7% (2) | 10% (3) | 8.3% (5) | |
| Diagonal | (10%) 3 | 10% (3) | 10% (6) | |
| ds | Not present | 30% (9) | 16.7% (5) | 23.3% (14) |
| No connection | 26.7% (8) | 33.3% (10) | 30% (18) | |
| Connection | 43.3% (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).