Superior Sagittal Sinus — Short Note

Definition & Location

Course

• Origin: Begins anteriorly at the crista galli (or foramen caecum), where it may communicate with tiny meningeal veins or, if the foramen caecum is patent, with a vein from the nose.
• Direction: Runs upward and backward in the superior border of the falx cerebri, becoming progressively larger (triangular on cross-section) as it passes posteriorly.
• Termination: Ends near the internal occipital protuberance, typically deviating to the right to become continuous with the right transverse sinus. The meeting point of multiple sinuses here is called the confluence of sinuses (torcular Herophili).

Interior of the Sinus

• Openings of the superior cerebral veins
• Venous lacunae (lateral extensions) — usually three on each side — which first receive diploic and meningeal veins
• Arachnoid villi and granulations projecting into the lacunae and the sinus itself (key sites of CSF absorption)
• Numerous fibrous bands crossing the angle of the sinus
• Openings of venous lacunae, usually on the lateral side

Tributaries

1. Superior cerebral veins — 8–12 veins draining the superolateral surface of the cerebral hemispheres; they open into the lateral lacunae (never directly)
2. Parietal emissary veins — connect the scalp veins to the sinus
3. Diploic veins — from the diploe of the skull bones
4. Venous lacunae — which drain diploic and meningeal veins before opening into the sinus
5. Occasionally, a nasal vein via the foramen caecum

Functional Significance

• Primary drainage channel for the cerebral cortex (superior and medial surfaces of both hemispheres)
• Critical site of CSF reabsorption via arachnoid granulations projecting into the lateral lacunae
• Communicates with the opposite transverse sinus (via the confluence), ensuring collateral drainage

Clinical Relevance