Venous sinuses

VENOUS SINUSES OF DURA MATER

Definition Features Classification Paired Unpaired

1 Definition

  • Dural venous sinuses are venous spaces or channels present in the dura mater.
  • They are lined by endothelium.

2 Features of Dural Venous Sinuses

Formation

Dural venous sinuses are formed in two ways:

  1. By separation of two layers of dura mater
  2. By folding of the meningeal layer on itself

Other Features

  1. Lined by endothelium only.
  2. Muscle coat is absent in their walls.
  3. Devoid of valves in their lumen.
  4. Receive both blood and CSF.
  5. Communicate with veins outside the skull through emissary veins.
Important: This helps to maintain constant blood pressure in the sinuses.

3 Classification of Dural Venous Sinuses

  • There are 23 venous sinuses:
  • 8 paired
  • 7 unpaired

A. Paired Venous Sinuses

There is one sinus each on the right and left side.

  1. Cavernous sinus
  2. Superior petrosal sinus
  3. Inferior petrosal sinus
  4. Transverse sinus
  5. Sigmoid sinus
  6. Sphenoparietal sinus
  7. Petrosquamous sinus
  8. Middle meningeal sinus/veins

B. Unpaired Venous Sinuses

These are median in position.

  1. Superior sagittal sinus
  2. Inferior sagittal sinus
  3. Straight sinus
  4. Occipital sinus
  5. Anterior intercavernous sinus
  6. Posterior intercavernous sinus
  7. Basilar plexus of veins