Practical 3 - station 2 - ventricles Flashcards
What are ventricles?
Irregularly shaped cavities in brain containing CSF
How many ventricles are there?
2 lateral
3d
4th
Which is the largest ventricle?
2 asymmetrical lateral cavities
What is the function of the interventricular foramen of Munro?
Allows the lateral ventricles to communicate with the 3rd ventricle
How is the 3rd ventricle connected to the 4th ventricle?
Cerebral aqueduct (runs through midbrain)
What is caudal to the 4th ventricle?
Medulla
How does CSF drain into the subarachnoid space?
From 4th ventricle via single median and 2 lateral apertures
How is CSF produced?
Secreted and continuously produced by choroid plexus of all ventricles
What is the total CSF volume?
150ml
How often is the CSF replaced?
Every 8 hours
How much CSF is formed daily?
Approx 500ml
What does CSF usually consist of?
Clear
colourless
blood plasma composition
very few cells - mostly lymphocytes
What aspect of the CSF indicates disease?
> 10 cells/ml
What are some functions of the CSF?
Liquid cushioning and buoyancy
Reduces brain weight by about 97% preventing it crushing under its own weight
Protects brain and spinal cord from blows and trauma
Nourishes the brain
Carries chemical signals (hormones) from one part of brain to another
What is the weight of the brain?
1.3kg
What direction does CSF flow in?
One way system - lateral to 3rd to 4th
Where does CSF enter circulation?
Choroid plexus in all 4 ventricles so can enter at any stage
Where does the CSF go after the 4th ventricle?
It can either enter the subarachnoid space via apertures or continue in the central canal of the medulla and spinal cord
How can the CSF exert pressure on the brain?
If a tumour or something else obstructs its circulation
What is hydrocephalus?
New born babies head enlarges as skull bones not fused and CSF blocked so exerts pressure on brain
Why does hydrocephalus only occur in new borns
In adults skull is more rigid and hard so accumulating fluid compresses the blood vessels and crushes the soft nervous tissue - get brain damage instead
