Session 2 - Meningeal Layers, Dural Folds amd Dural Venous Sinuses

Question 1

What are the meninges? Name the layers.

Answer 1

3 membranous layers that surround and protect the brain.

Dura - tough fibrous membrane
Arachnoid - soft translucent membrane
Pia - microscopically thin, delicate, closely adherent to the surface of the brain

Question 2

What are the two layers of the dura?

Answer 2

Periosteal - periosteum lining inner table of the skull

Meningeal - layer adjacent to the arachnoid

Question 3

What are the two dural folds?

Answer 3

Falx cerebri

Tentorium cerebelli

Question 4

The falx cerebri attaches to what structure anteriorly?

Answer 4

Crista galli

Question 5

What is the purpose of dural folds?

Answer 5

Help to stabilise the brain

Act as rigid dividers

Question 6

In some cases, a rise in intracranial pressure (e.g. secondary to a bleed) can lead to compression of the brain and therefore herniation through which foramen?

Answer 6

Foramen magnum

Question 7

What are dural venous sinuses?

Answer 7

Venous blood filled channels created by separation of the meningeal layer from the periosteal layer of dura.

Question 8

Dural venous sinuses will eventually drain into what vein?

Answer 8

Internal jugular vein

Question 9

What are bridging veins?

Answer 9

Veins that pass from the subarachnoid space to dural venous sinuses, passing through the subdural space.

Question 10

Damage to bridging veins is normally responsible for what sort of haemorrhage?

Answer 10

Subdural haemorrhage

Question 11

Where does bleeding occur in the following types of haemorrhage; extradural, subdural, subarachnoid, intracerebral.

Answer 11

Extradural - between the periosteal layer of dura and the bone
Subdural - between the meningeal layer of dura and the arachnoid layer
Subarachnoid - between the arachnoid and pia
Intracerebral - within the brain tissue itself

Question 12

Would an extradural haemorrhage be a venous or arterial bleed?

Answer 12

Arterial bleed

Question 13

Would a subdural haemorrhage be a venous or arterial bleed?

Answer 13

Venous bleed

Question 14

Would a subarachnoid haemorrhage be a venous or arterial bleed?

Answer 14

Arterial bleed

Question 15

Why can lumbar punctures be useful in diagnosing a subarachnoid haemorrhage?

Answer 15

In a subarachnoid haemorrhage blood leaks into the subarachnoid space, mixing with cerebrospinal fluid. A lumbar puncture samples the CSF so can identify the presence of blood.

Question 16

How would an infection around the orbit spread intracranially?

Answer 16

Pass through the opthalmic veins which communicate with the cavernous sinus (through the back of the orbit).