The occipital sinus is the smallest of all dural venous sinuses. It lies in the base of the falx cerebelli on the inner side of the occipital bone.
The occipital sinus drains the blood from the marginal sinus, which is a venous vessel situated along the rim of the foramen magnum. It terminates at the level of the occipital protuberance where it contributes to the formation of the confluence of sinuses, together with the superior sagittal, transverse and straight sinuses.
|Drains from||Marginal sinus, posterior internal vertebral venous plexus|
|Drains to||Confluence of sinuses|
|Drainage area||Vertebral column, spinal cord|
This article will discuss the anatomy and function of the occipital sinus.
Anatomy and course
The occipital sinus originates at the level of the foramen magnum via several small veins arising from the marginal sinus and posterior internal vertebral venous plexus. It ascends along the posterior margin of the falx cerebelli, which attaches along the internal occipital crest of the occipital bone. The occipital sinus terminates at the level of the occipital protuberance by emptying into the confluence of sinuses.
Since it communicates with the posterior internal vertebral plexus, the occipital sinus receives a small amount of blood from the spine and the spinal cord. Thereby, the occipital sinus connects the extracranial with the intracranial venous systems and hence can be considered an emissary vein.
The most prominent function of the occipital sinus is to provide an alternative route for the venous drainage of the vertebral column when the venous return through the internal jugular vein is compromised. Also, in case of the absence of the transverse sinus, the occipital sinus becomes the main pathway for venous drainage of the brain.
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