Meninges, Venous Drainage of the Brain and CSF

Question 1

Describe the cisterns and their locations in the cranium

Answer 1

• interpeduncular cistern: between cerebral peduncles in the midbrain
• cisterna pontis: caudal to the bulge of the pons
• superior cistern: dorsally between superior and inferior colliculi
• cisterna magna: inferior to cerebellum (where CSF can be sampled if unable to from lumbar region)

Question 2

Describe the venous drainage of the brain

Answer 2

External and internal cerebral veins emerge from the superior sagittal sinus and lie in the subarachnoid space. It drains to the confluence of sinuses.

Transverse sinus drains to sigmoid sinus.

Straight sinus drains to inferior sagittal sinus and great cerebral vein to the sigmoid sinus.

Question 3

Describe the drainage of the deep structures of the brain

Answer 3

The great cerebral vein gives off the basal vein (from the medial temporal lobe), the internal cerebral vein (which drains choroidal vein and thalamostriate vein) and veins that drain the caudate nucleus of the dorsal striatum.

Question 4

Describe the drainage of the cavernous sinus

Answer 4

2 routes:

• can go through superior petrosal sinus that drains to transverse and sigmoid sinuses
• can drain to basilar plexus to inferior petrosal sinus towards the sigmoid sinus

Question 5

Describe the formation and drainage of CSF

Answer 5

• formed by choroid plexuses in the ventricles (epithelium lined with ependymal cells that secrete CSF) and leaks of CSF directly from the brain
• it flows out of the ventricular system into the subarachnoid space through apertures in the 4th ventricle (2 lateral and 1 median)
• it then flows upwards and around the brain to drain into the subarachnoid granulations to the superior sagittal sinus