Clinical Tools › Fetal Brain Development

Fetal Cortical Sulcation & Brain Development

Explore the appearance timeline of fetal sulci, gyri and key structures across anatomy / prenatal ultrasound / fetal MRI, distinguishing earliest visible from reliably visible. Enter a gestational age to read out whether each structure should be visible, with clinical significance and red flagsper structure (e.g. delayed central/convexity sulci → lissencephaly; absent CSP → callosal agenesis / septo-optic dysplasia). Covers Sylvian fissure + insular opercularization, parieto-occipital, calcarine, cingulate, central, superior temporal, frontal sulci, olfactory sulcus, hippocampal fissure, corpus callosum, cavum septi pellucidi, ventricular atrium and cerebellar vermis. Evidence-based on Toi 2004, Cohen-Sacher 2006, Chi 1977, Garel, Barkovich and the ISUOG guideline.

① Choose modality

② Gestational age (optional — per-structure read-out)

Prenatal ultrasound · Developmental timeline

Hippocampal fissure / hippocampal inversionfissure

Medial temporal (limbic)

Earliest visible：16–18 周 · Reliably visible：≈20 周恒定 · Plane：Coronal (temporal horn)

Sylvian fissure + insular opercularizationfissure + operculization

Lateral convexity / insula

Earliest visible：14–16 周（浅凹） · Reliably visible：外侧沟/岛叶 22 周 100% 可见；盖化角：钝角约 20 周、锐角约 24 周 · Plane：Transthalamic axial / coronal

Cavum septi pellucidicavity

Midline (between septal leaves)

Earliest visible：16–18 周 · Reliably visible：18–37 周应稳定可见（BPD 平面必测）；37–40 周后由后向前正常闭合 · Plane：Transthalamic axial (BPD plane)

Lateral ventricle (atrial width + choroid plexus)ventricle

Supratentorial ventricles

Earliest visible：15–16 周起可测 · Reliably visible：房部横径正常 <10 mm；10–15 mm 轻度脑室扩张；≥15 mm 重度 · Plane：Transventricular axial (inner-to-inner at atrium)

Parieto-occipital fissurefissure

Medial hemisphere (parieto-occipital)

Earliest visible：18.5 周（Toi）；部分 16–17 周 · Reliably visible：>20.5 周 95% 可见（Cohen-Sacher）；23 周 100% 可见 · Plane：Parasagittal / axial

Calcarine sulcussulcus

Medial occipital (visual cortex)

Earliest visible：18.5 周（Toi） · Reliably visible：>21.9 周 95% 可见；24–27 周 100% 可见 · Plane：Parasagittal

Corpus callosumcommissure

Midline commissure

Earliest visible：经阴道 16–18 周 · Reliably visible：正中矢状面 18–20 周可完整显示并测长度（随孕周增长） · Plane：Mid-sagittal (preferred) + coronal

Cerebellar vermis foliationcerebellum

Posterior fossa (midline cerebellum)

Earliest visible：经小脑轴位可测（TCD） · Reliably visible：≥18–20 周蚓部应完整覆盖四脑室；原裂等 foliation ≥24 周可辨 · Plane：Transcerebellar axial + vermian mid-sagittal

Cingulate sulcussulcus

Medial hemisphere (above corpus callosum)

Earliest visible：23.2 周（Toi）；扣带回可早至 18 周 · Reliably visible：>24.3 周（Toi）；Slagle：平均 26 周首现，分支 30–34 周；约 25% 迟至 24–25 周才见 · Plane：Mid/parasagittal

Central (Rolandic) sulcussulcus

Lateral convexity (fronto-parietal)

Earliest visible：约 24–26 周（属 convexity 沟） · Reliably visible：凸面沟 >27.9 周恒定可见（Toi） · Plane：Convexity parasagittal/coronal

Superior temporal sulcussulcus

Lateral temporal lobe

Earliest visible：约 26–28 周 · Reliably visible：>28–30 周 · Plane：Temporal parasagittal/axial

Pre- and post-central sulci (convexity)sulci

Lateral convexity

Earliest visible：约 26–28 周 · Reliably visible：>28–30 周 · Plane：Convexity

Superior / inferior frontal sulcisulci

Dorsolateral frontal lobe

Earliest visible：约 28–30 周 · Reliably visible：>30–32 周 · Plane：Frontal coronal/parasagittal

Olfactory sulcus / bulbsulcus

Inferior frontal (orbital) surface

Earliest visible：超声难以稳定显示 · Reliably visible：常需 MRI；US 价值有限 · Plane：Frontal-base coronal (limited)

Gestational ages are consensus ranges and vary by method and individual; 'earliest' = first detectable in some fetuses, 'reliable' = visible in the great majority (>95%/100%). For licensed clinicians; does not replace clinical judgment and full neuroimaging assessment. Sources: Toi 2004, Cohen-Sacher 2006, Chi 1977, Garel AJNR 2001, Barkovich, and the ISUOG CNS guideline.

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