Sulcal presence according to GA, adapted from Garel1
| GA (Weeks) | Sulci Present | Additional Sulci Present |
|---|---|---|
| 22–23 | Interhemispheric fissure | |
| Lateral sulcus | ||
| Internal parieto-occipital fissure | ||
| Hippocampal fissure | ||
| Callosal sulcus | ||
| 24–25 | Calcarine fissure | |
| Cingular sulcus | ||
| 26 | Central sulcus | |
| Collateral sulcus | ||
| 27 | Marginal sulcus | |
| Precentral sulcus | ||
| Superior (posterior) temporal sulcus | ||
| 28 | Postcentral sulcus | |
| Intraparietal sulcus | ||
| 29 | Superior frontal sulcus | |
| Inferior frontal sulcus | ||
| 30 | None | |
| 31 | None | |
| 32 | Superior (anterior) temporal sulcus | |
| Inferior temporal sulcus | ||
| 33 | Occipitotemporal sulcus | |
| Secondary cingular sulcus | ||
| 34 | Insular sulci | |
| Secondary occipital sulci |
Note:—The presence of a given sulcus is defined by Garel as present in at least 75% of the population for a particular gestation.