M02.05.003 Dural Venous Sinuses

Learning Objective

By the end of this article, you should be able to:
Describe the anatomy, structure, and drainage pathways of the dural venous sinuses, including their clinical relevance, particularly concerning cavernous sinus thrombosis.

Introduction

The dural venous sinuses are a group of venous channels located within the cranial cavity, formed between the two layers of the dura mater (periosteal and meningeal). These sinuses serve as the primary drainage system for venous blood from the brain, ultimately emptying into the internal jugular vein.

🔍 Note: This article focuses specifically on the dural venous sinuses. For a broader discussion on CNS venous drainage, refer to our overview of venous drainage of the central nervous system.

Overview of the Dural Venous System

The dural sinuses receive blood from multiple sources:

• Cerebral, cerebellar, and brainstem veins
• Diploic veins (within the cranial bones)
• Emissary veins (connecting scalp veins with intracranial venous sinuses)

Blood from these sources drains through a network of paired and unpaired dural sinuses, which converge and exit the skull via the internal jugular veins.

Unpaired Dural Venous Sinuses

These sinuses run predominantly along the midline of the brain:

1. Superior Sagittal Sinus

• Largest dural venous sinus
• Located in the superior margin of the falx cerebri
• Extends from the frontal crest to the internal occipital protuberance
• Drains into the confluence of sinuses

2. Inferior Sagittal Sinus

• Smaller and lies in the inferior margin of the falx cerebri
• Drains the medial cerebral hemispheres and the falx cerebri
• Joins the great cerebral vein to form the straight sinus

3. Straight Sinus

• Formed by the union of the inferior sagittal sinus and the great cerebral vein
• Courses where the falx cerebri meets the tentorium cerebelli
• Drains into the confluence of sinuses

4. Occipital Sinus

• Smallest sinus
• Located within the falx cerebelli
• Runs from the foramen magnum to the confluence of sinuses

5. Intercavernous Sinuses

• Connect the right and left cavernous sinuses
• Typically consists of anterior and posterior components
• Encircle the pituitary stalk

Paired Dural Venous Sinuses

These sinuses are located laterally on both sides of the cranial cavity:

1. Transverse Sinuses

• Begin at the confluence of sinuses
• Travel along the posterolateral margin of the tentorium cerebelli
• Continue as the sigmoid sinuses

2. Sigmoid Sinuses

• S-shaped continuation ofthe transverse sinuses
• Located along the temporal and occipital bones
• Exit skull via jugular foramen, becoming the internal jugular veins

3. Cavernous Sinuses

• Found on either side of the sella turcica in the sphenoid bone
• Receive drainage from:
  • Ophthalmic veins
  • Superficial middle cerebral vein
  • Sphenoparietal sinus
• Drained by:
  • Superior and inferior petrosal sinuses
  • Intercavernous sinuses (for interconnection)

4. Superior Petrosal Sinuses

• Drain from the cavernous sinus to the transverse sinus
• Located along the petrous part of the temporal bone
• Also receives drainage from inferior cerebral veins, cerebellar veins, and the labyrinthine vein

5. Inferior Petrosal Sinuses

• Begin at the posterior cavernous sinus
• The course between the petrous temporal bone and the occipital bone
• Empty into the internal jugular vein

Additional Venous Structure: Basilar Venous Plexus

• Found on the posterior cranial base (behind the sella turcica)
• Interconnects the inferior petrosal sinuses and communicates with the vertebral venous plexus

Clinical Relevance: Cavernous Sinus Thrombosis (CST)

Definition:
CST is the formation of a blood clot within the cavernous sinus, most often due to infection.

Etiology:

• Frequently results from facial infections, especially from the danger triangle of the face
• Infection spreads via the facial vein → ophthalmic veins → the cavernous sinus

Clinical Features:

• Headache
• Unilateral periorbital edema
• Proptosis (eye bulging)
• Photophobia
• Cranial nerve palsies, especially abducens nerve (CN VI) involvement

Management:

• Prompt antibiotic therapy
• Severe cases may progress to meningitis if untreated

Summary Table: Dural Venous Sinuses

Points to Remember

• Dural venous sinuses are valveless, allowing bidirectional flow, which can facilitate the spread of infections.
• The confluence of sinuses is a key anatomical meeting point for several unpaired sinuses.
• The cavernous sinus has rich connections with facial veins, key in understanding cavernous sinus thrombosis.
• The internal jugular vein is the final outflow tract for the entire dural venous sinus system.

References

1. Standring S. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. Elsevier; 2020.
2. Snell RS. Clinical Anatomy by Regions. 10th ed. Wolters Kluwer; 2018.
3. TeachMeAnatomy. Dural Venous Sinuses
4. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. 8th ed. Wolters Kluwer; 2018.