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The sigmoid sinus is a dural venous sinus situated within the dura mater.The sigmoid sinus receives blood from the transverse sinuses, which track the posterior wall of the cranial cavity, travels inferiorly along the parietal bone, temporal bone and occipital bone, and converges with the inferior petrosal sinuses to form the internal jugular vein.
The transverse sinuses (left and right lateral sinuses), within the human head, are two areas beneath the brain which allow blood to drain from the back of the head. They run laterally in a groove along the interior surface of the occipital bone .
The dural venous sinuses (also called dural sinuses, cerebral sinuses, or cranial sinuses) are venous sinuses (channels) found between the periosteal and meningeal layers of dura mater in the brain. [ 1 ] [ 2 ] They receive blood from the cerebral veins , and cerebrospinal fluid (CSF) from the subarachnoid space via arachnoid granulations .
A sigmoid function is any mathematical function whose graph has a characteristic S-shaped or sigmoid curve. A common example of a sigmoid function is the logistic function , which is defined by the formula: [ 1 ]
The confluence of sinuses shows significant variation. [1] Most commonly, there is a continuous connection between all of the sinuses. [1] [2] A very common variant is the superior sagittal sinus only draining into the right transverse sinus - more rarely, it may also only drain into the left transverse sinus.
The parietal emissary vein connects it with the superior sagittal sinus. [2] As the occipital vein passes across the mastoid portion of the temporal bone, it usually receives the mastoid emissary vein, which connects it with the sigmoid sinus. [2] [3] The occipital diploic vein sometimes joins it.
Where the apex of the petrous temporal meets the squamous temporal, the transverse sinuses lead into sigmoid (S-shaped) sinuses (one on each side). These pass along the articulation between the posterior edge of the petrous temporal bone and the anterior edge of the occipital bones to the jugular foramen , where the sigmoid sinus becomes the ...
Sigmoid means resembling the lower-case Greek letter sigma (uppercase Σ, lowercase σ, lowercase in word-final position ς) or the Latin letter S. Specific uses include: Sigmoid function, a mathematical function; Sigmoid colon, part of the large intestine or colon; Sigmoid sinus, two structures that drain blood from the bottom of the brain