Sigmoid sinus

A key venous channel responsible for draining blood from the brain.

The sigmoid sinus is a large venous sinus located within the dura mater, the outermost covering of the brain. It serves as a crucial pathway for venous blood, collecting deoxygenated blood from various structures in the brain and directing it towards the internal jugular vein. This sinus is named for its S-shaped curve, which is characteristic of its anatomical structure.

Terminologia Anatomica

sinus sigmoidalis

System

Circulatory system

Function

The primary function of the sigmoid sinus is to collect blood from the brain's cranial cavity, including blood from the superior sagittal sinus and the transverse sinuses. After receiving blood from these sources, the sigmoid sinus drains into the internal jugular vein, facilitating the return of deoxygenated blood back to the heart. This process is vital for maintaining proper cerebral circulation and ensuring that metabolic wastes are efficiently removed from the brain tissue. Additionally, the sigmoid sinus plays a role in regulating intracranial pressure, as the flow of blood through this sinus can influence the venous drainage and overall pressure within the cranial cavity.

Location

The sigmoid sinus is located in the posterior cranial fossa, specifically within the dura mater along the lateral aspect of the skull. It begins at the transition from the transverse sinus, which runs horizontally across the skull, and arches downward to form the sigmoid shape before terminating at the internal jugular vein at the base of the skull. This anatomical positioning is essential because it allows the sigmoid sinus to effectively collect blood from various regions of the brain and provides a direct pathway for drainage.

Did You Know?

The sigmoid sinus is one of several dural venous sinuses that play a key role in brain drainage.
Although it is classified as a sinus, it is actually a venous channel rather than a true anatomical vein.
The drainage from the sigmoid sinus directly affects the overall circulation of cerebrospinal fluid within the brain.