Dural venous sinuses

Dural Venous Sinuses

Diagram showing the major dural venous sinuses in the human brain.

The dural venous sinuses are a network of venous channels located between the two layers of the dura mater, the outermost protective covering of the brain. These sinuses play a crucial role in draining deoxygenated blood and cerebrospinal fluid from the brain and delivering it back to the systemic circulation.

Anatomy

The dural venous sinuses are formed by the separation of the two layers of the dura mater, known as the periosteal layer and the meningeal layer. They are lined with endothelial cells and are devoid of valves, allowing for bidirectional blood flow. The major dural venous sinuses include:

1. Superior sagittal sinus: This sinus runs along the superior midline of the brain, within the superior sagittal sulcus. It receives blood from the cerebral hemispheres and drains into the confluence of sinuses.

2. Inferior sagittal sinus: Located in the inferior midline of the brain, within the inferior sagittal sulcus, this sinus drains into the straight sinus.

3. Straight sinus: Formed by the confluence of the superior sagittal sinus and the inferior sagittal sinus, the straight sinus runs along the tentorium cerebelli and drains into the confluence of sinuses.

4. Transverse sinuses: These sinuses run horizontally along the posterior aspect of the brain, within the attached margin of the tentorium cerebelli. They receive blood from the confluence of sinuses and drain into the sigmoid sinuses.

5. Sigmoid sinuses: The sigmoid sinuses continue from the transverse sinuses and run in an S-shaped curve within the posterior cranial fossa. They drain into the internal jugular veins.

6. Confluence of sinuses: This is the meeting point of the superior sagittal sinus, straight sinus, and occipital sinus. It is located at the internal occipital protuberance.

7. Occipital sinus: This sinus runs along the posterior midline of the brain, within the attached margin of the falx cerebelli. It drains into the confluence of sinuses.

Function

The dural venous sinuses serve several important functions in the brain. They act as a drainage system, collecting deoxygenated blood and cerebrospinal fluid from the brain and delivering it back to the systemic circulation. Additionally, they help regulate intracranial pressure by absorbing excess cerebrospinal fluid.

The dural venous sinuses also play a role in the immune response of the brain. They contain immune cells that help protect the brain from infections and other harmful substances.

Clinical Significance

The dural venous sinuses can be affected by various pathological conditions. Thrombosis, or the formation of blood clots within the sinuses, can lead to venous congestion and increased intracranial pressure. This can result in symptoms such as headache, visual disturbances, and neurological deficits.

Infections, such as meningitis, can also involve the dural venous sinuses. In severe cases, the infection can spread to the sinuses, causing inflammation and potentially leading to complications.