Meninges, venous drainage of the brain and CSF

Question 1

Highlight the main layers of the meniges and their properties

Answer 1

• Dura mater - tough fibrous bridges crevices, attached to the skull
• Arachnoid mater - delicate, sealed bag for CSF; bridges crevices
• Arachnoid trabeculae - “ropes” across subarchnoid space
• Pia mater - delicate; dips into crevices

Question 2

What is contained in the dura mater of the skull?

Answer 2

branches of the middle menigeal artery

Question 3

What is the function of cisterns and name the main cisterns of the brain

Answer 3

• interpeduncular
• cisterna pontis
• superior cistern
• cisterna magna (cerebellomedullaris)

Question 4

What arterial feature lies in the subarchnoid space?

Answer 4

arterial circle of willis

Question 5

Why are the roots so long at the spinal cord end?

Answer 5

Question 6

What is the safest location to take a lumbar puncture?

Answer 6

• subarchnoid space
• well below L2 - usually L4/5

Question 7

Describe the veins of the brain

Answer 7

• Veins of the brain have thin walls and no valves
• Emerge from brain and lie in the subarachnoid space
• Drain into cranial venous sinuses
• Grouped into external (quite variable) and internal cerebral veins

Question 8

Draw a diagram indicating the sinuses of the brain and describe how are they arranged?

Answer 8

arranged along the borders of folds of dura

Question 9

Why is the tentorial notch?

Answer 9

danger point during increased intracranial pressure; transtentorial herniation

Question 10

Describe the veins above the thalamus

Answer 10

Question 11

Highlight the main sinuses of the venous system in the brain

Answer 11

• superior saggital sinus
• inferior sagittal sinus
• straight sinus
• confluence of sinuses
• transverse sinuses
• sigmoid sinus
• inferior and superior petrosal sinus
• cavernous sinus
• sphenoparietal sinus
• intercavernous sinus

Question 12

What is cerebrospinal fluid (CSF)

Answer 12

• Clear colourless fluid which fills the ventricles of the brain, surrounds the brain and spinal cord

Question 13

What is the content of CSF within the body?

Answer 13

• 150ml produced at 0.5ml/min and turns over 4 times a day

Question 14

Where is CSF formed?

Answer 14

• Formed in the choroid plexus (up to half from blood vessels surrounding the ventricles)
• Core vascular tissue (in pia) covered by an epithelium which secretes cerebrospinal fluid

Question 15

Where does CSF flow to/turn over?

Answer 15

• CSF flows out of ventricle system into the subarachnoid space via apertures in fourth ventricle

Question 16

Highlight the direction of flow of the CSF

Answer 16

Question 17

What is responsible for CSF uptake in the subarchnoid space?

Answer 17

Uptake of CSF from the subarachnoid space in arachnoid granulations and then superior sagittal sinus

Question 18

What is hydrocephalus caused by?

Answer 18

• Due to blocked transport (non-communicative), or to over productive/blocked absorption of CSF (communicative)