Meninges and dura

Question 1

Describe the layers on the meninges and what sits between them. (6)

Answer 1

Pia - the most internal layer, adhered tightly to the brain and spinal cord surface
Sub-arachnoid space - CSF here.
Arachnoid - middle layer, spidery, doesn’t go into sulci but does into sagittal fissure. Doesn’t surround spinal cord.
Meningeal dura - tightly adhered to arachnoid.
Duran venous sinuses and Duran folds like tentorium cerebelli and fall cerebri here.
Periosteal dura - adhered tightly to the inner table of the skull bone.

Question 2

Explain the purpose of the dural folds, and explain the drawbacks of having them relating to this function. (3)

Answer 2

They reinforce and separate the brain. However, because they are so rigid, in raised intracranial pressure, they can lead to compression of the brain or herniation of the brain through the tentorial notch and through the foramen Magnus.

Question 3

Describe extradural haemorrhage. (3)

Answer 3

An arterial bleed between meningeal and periosteal dura that occurs only with significant trauma. Appears lemon shaped on CT because the blood cannot pass through the dura where it travels between the sutures in bone.

Question 4

Describe subdural haemorrhage. (3)

Answer 4

A venous bleed usually from bridging veins. They can be chronic, especially in the elderly. They appear banana shaped on CT, and can be similar in colour to brain matter if they’re aged.

Question 5

Describe subarachnoid haemorrhage. (4)

Answer 5

A sudden arterial bleed that occurs secondary to severe trauma or an aneurysm bleed. Blood leaks into the subarachnoid space and mixed with CSF. Often not visible on CT, need lumbar puncture.