Sigmoid sinus

Sigmoid sinus

The Sigmoid sinus is a dural venous sinus of the human body. It receives blood from the transverse sinuses and continues as the internal jugular vein.

Anatomy

The sigmoid sinus, also known as the pars sigmoida, is a part of the dural venous sinuses. It is a continuation of the transverse sinus and is connected to the internal jugular vein. The sinus is shaped like the Greek letter sigma (Σ), hence the name 'sigmoid'.

The sigmoid sinus begins near the mastoid foramen, travels posteriorly and inferiorly, and then turns medially to become the internal jugular vein. It is located within the dura mater, a layer of the meninges that surrounds the brain and spinal cord.

Function

The primary function of the sigmoid sinus is to drain blood from the brain. It receives blood from the transverse sinuses, which in turn receive blood from the superior sagittal sinus and inferior sagittal sinus. The sigmoid sinus then drains into the internal jugular vein, which carries deoxygenated blood away from the brain and towards the heart.

Clinical significance

The sigmoid sinus can be involved in several medical conditions. Thrombosis (clotting) in the sigmoid sinus can lead to cerebral venous sinus thrombosis, a serious condition that can cause stroke-like symptoms. The sigmoid sinus can also be affected by pulsatile tinnitus, a condition where a person hears a rhythmic pulsing sound, often in time with their heartbeat.

See also

• Dural venous sinuses
• Internal jugular vein
• Transverse sinus