Ventricles & CSF

Summary

• Ventricles of the brain
  • CSF

Ventricles of the brain

• This are cavities within the brain filled with CSF
• 4 ventricles to consider:
  1. Two lateral ventricles (1st and 2nd)
  2. 3rd ventricle 
  3. 4th ventricle

  4. 

Cerebrospinal Fluid (CSF)

• This is a fluid within the ventricles and subarachnoid space around the brain and spinal cord
  • Composition similar to blood but less protein and different ionic composition

    

• Functions
  • Provides nutrition
  • Key in protecting the brain against damage
  • Maintains buoyancy
  • Blood Brain Barrier

• Secreted by choroid plexuses
  • Transferred back into venous blood via arachnoid granulations

Circulation of CSF

• CSF is constantly secreted, circulating and reabsorbed in ventricles

1. Secreted by choroid plexuses
   • One set in each ventricle
2. Lateral ventricles => 3rd ventricle (via interventricular foramen)
3. 3rd => 4th ventricle (via Aqueduct of Sylvius)
4. 4th ventricle => subarachnoid space via medial and lateral apertures
   • Spreads around the spinal cord and cerebellum within the subarachnoid space
5. Majority then enters Subarachnoid cisterns
   • These are expanded areas which contain most of the CSF
   • Distribute CSF around cerebrum
6. Reabsorbed by arachnoid granulations
   • These structures communicate the subarachnoid space to venous sinuses in dura
     • Particularly into sagittal venous sinus

• NB foramina and cerebral aqueduct are easily blocked
  • => Hydrocephalus

• CSF can be sampled via lumbar puncture
  • Needle into the subarachnoid space in the spine