Venous Drainage of the Brain

Summary

  • Overview
  • Venous sinuses
    • Cavernous Sinus

Overview of Venous Drainage

  • The venous drainage of the brain tissue is done via the venous sinuses
    • These are endothelium lined spaces within the intradural space (i.e. between the two dural layers)

  • Sinuses drain blood from the brain from two key sources via lacunae 
    1. Internal veins of the brain
    2. CSF via arachnoid granulations
  • Finally, the sinuses then drain into the internal jugular vein
  • Therefore the blood flows from CSF/internal veins => venous sinuses => IJV => heart

The Venous sinuses

  • There are a number of sinuses to consider
Venous sinuses (looking from an posterior/left position)

Useful schematic of the venous sinuses. Note that all ultimately drain into the IJV.

  1. Superior Sagittal sinus
    • Runs in falx cerebri
    • Drains directly into confluence of sinuses
  2. Inferior Sagittal sinus
    • Drains into straight sinus
  3. Great cerebral vein
    • Drains into straight sinus
  • These drain into 2 structures
  1. Straight sinus
    • Formed from ISS + GCV at union of falx cerebri and tentorium cereblli
    • Drains into the confluence of sinuses
  2. Confluence of sinuses which is formed  from the straight sinus + superior sagittal sinus
  • The Confluence of sinuses then drains into:
  1. Transverse sinuses
    • Formed from confluence of sinuses
    • Run in attached border of  tentorium cerebelli
    • Drain into sigmoid sinus
  2. Cavernous sinus
    • Drain into sigmoid sinus via superior petrosal sinus and IJV directly via inferior petrosal sinus
  3. Sigmoid sinuses
    • Receives blood from transverse sinuses (from confluence) and the superior petrosal sinus (which drains the  cavernous sinuses)
    • Drains into IJV at jugular foramen

 


The Cavernous sinus
  • This is a venous sinus  but important due to it’s anatomical relations – in particular the ICApituitary gland, and cranial nerves
  • There are two cavernous sinuses, one for each side of brain
    • Separated by the sphenoid sinus & pituitary gland

 

  • The cavity of the sinus is  bordered by:
    • Diaphragma sellae superiorly
      • Formed from meningeal dura
    • Sella turcica inferiorly (+ greater wing of sphenoid)
    • Temporal lobe laterally
    • Sphenoid sinus medially
    • Superior orbital fissure anteriorly
    • Petrous part of temporal bone posteriorly
  • Contains several key structures besides venous blood
    1. Internal carotid arteries
    2. CNIII – VI (except V3)
    3. NB the pituitary is not within the sinus  itself

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