Superior sagittal sinus

Structure

It is triangular in section. It is narrower anteriorly, and gradually increases in size as it passes posterior-ward.

It commences at the foramen cecum, through which it receives emissary veins from the nasal cavity. It passes posterior-ward along its entire course. It is accommodated within a groove which runs across the inner surface of the frontal bone, the adjacent margins of the two parietal lobes, and the superior division of the cruciate eminence of the occipital lobe. Near the internal occipital protuberance, it deviates to either side (usually the right) before draining into the confluence of sinuses, continuing as the corresponding transverse sinus.

The superior sagittal sinus is usually divided into three parts: anterior (foramen cecum to bregma), middle (bregma to lambda), posterior (lambda to confluence).

Its inner surface presents the openings of the superior cerebral veins, which run, for the most part, obliquely forward, and open chiefly at the back part of the sinus, their orifices being concealed by fibrous folds; numerous fibrous bands (chordae Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunae, also called 'lateral lacunae' or 'lacunae laterales') in the dura mater near the sinus.

Venous lacunae

There are usually three lacunae on either side of the sinus: a small frontal, a large parietal, and an occipital, intermediate in size between the other two.

Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations (Pacchionian bodies) project into them from below.

Tributaries

The superior sagittal sinus receives the superior cerebral veins, veins from the diploë and dura mater, and, near the posterior extremity of the sagittal suture, veins from the pericranium, which pass through the parietal foramina.

Function

Cerebrospinal fluid drains through arachnoid granulations into the superior sagittal sinus and is returned to venous circulation.

Additional images

File:Sobo 1909 590.png|Brain with sagittal sinus at centre, with various lacunae. File:Gray133.png|Left parietal bone. Inner surface. File:Gray135.png|Frontal bone. Inner surface. File:Gray193.png|Base of the skull. Upper surface. File:Gray769.png|Diagrammatic representation of a section across the top of the skull, showing the membranes of the brain, etc. File:Gray1196.png|Diagrammatic section of scalp. File:Human brain dura mater description.JPG|Human brain dura mater File:Slide6Neo.JPG|Meninges and superficial cerebral veins. Deep dissection. Superior view. File:Slide7Neo.JPG|Meninges and superficial cerebral veins. Deep dissection. Superior view.

References

References

1. Richard Snell's Clinical anatomy 8th Ed
2. "Clinically Oriented Anatomy". Wolters Kluwer, Lippincott Williams &Wilkins.
3. Salunke, P., Sodhi, H. B. S., Aggarwal, A., Ahuja, C. K., Dhandapani, S. S., Chhabra, R., & Gupta, S. K. (2013). Is ligation and division of anterior third of superior sagittal sinus really safe? Clinical Neurology and Neurosurgery, 115(10), 1998–2002. http://doi.org/10.1016/j.clineuro.2013.06.003