Occipital sinus

At a glance

English

Occipital sinus

Latin (TA2)

Sinus occipitalis

System

Vein

Region

Head

Side

Single, on the midline

About the occipital sinus

The occipital sinus is a small venous channel within the dura mater of the posterior cranial fossa. It lies in the attached margin of the falx cerebelli, the small fold of dura that projects forwards between the two halves of the cerebellum, along the internal occipital crest of the occipital bone.

It begins below near the margin of the foramen magnum, where it is linked with small venous channels around the foramen and through them with the internal vertebral venous plexus. From there it climbs in the midline along the crest to end at the confluence of sinuses, where it meets the superior sagittal, straight and transverse sinuses. It is sometimes paired, and its size varies widely between individuals; in some it is barely present, while in others it is large and forms an important drainage route.

It drains blood from the dura around it and links the venous system inside the skull with the veins of the vertebral canal, one of several such connections that allow venous blood to bypass a blocked pathway. Its main practical importance is in surgery of the back of the head. When the dura is opened in the midline below the confluence, for example to decompress the foramen magnum or to remove a tumour of the cerebellum, a large occipital sinus can bleed briskly and must be recognised on scans beforehand and controlled during the operation.

Course and drainage

Begins at

Venous channels at the margin of the foramen magnum, connected with the internal vertebral venous plexus.

Drains into

Confluence of sinuses at the internal occipital protuberance.

Drains

Drains the surrounding dura of the posterior cranial fossa and connects the dural sinuses with the vertebral venous plexus.