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Superior sagittal sinus
The superior sagittal sinus (also known as the superior longitudinal sinus), within a human head, is an area above/behind the brain, which allows blood veins to span the area, from the top of the head towards the back. It is believed that the cerebrospinal fluid drains through the arachnoid granulations into the dural venous sinuses of the superior sagittal sinus.
The sinus drains, along the top and back of the brain, to the transverse sinuses, then to the sigmoid sinuses (at the center of the head), at the internal jugular vein. See diagram (at right): labeled above the brain as "SIN. SAGITALLIS SUP." (for Latin: sinus sagittalis superior).
The superior sagittal sinus occupies the attached or convex margin of the falx cerebri.
Commencing at the foramen cecum, through which it receives a vein from the nasal cavity, it runs from anterior to posterior, grooving the inner surface of the frontal, 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), and is continued as the corresponding transverse sinus.
It is triangular in section, narrow in front, and gradually increases in size as it passes backward.
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 (chordæ Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunæ) in the dura mater near the sinus.
There are usually three lacunæ 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.
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.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Superior_sagittal_sinus". A list of authors is available in Wikipedia.|