Meninges

Question 1

What layers form the meninges

Answer 1

Pia

Arachnoid

Dura

Question 2

Describe the Pia

Answer 2

Inner layer of meninges that covers the whole brain and covers the spinal cord - continuous

Covers all folds of the brain -> cannot be separated

Question 3

Describe the arachnoid

Answer 3

Soft, translucent middle layer

Does not go into the folds of the brain but does dip into the great longitudinal fissure - arachnoid is an outer covering

Question 4

What space is found between the pia and arachnoid. Describe this space

Answer 4

Subarachnoid space

Contains CSF which pushes the arachnoid off the surface of the pia - pushed arachnoid onto the dura

Question 5

Describe the dura

Answer 5

Tough fibrous, outer layer of the meninges

Difficult to remove as it is stuck to the skull bones

Is continuous with the spinal cord

It is formed of two layers: periosteal and meningeal

Layers are mostly closely adherent but meningeal layer can peel off periosteal to form dural folds and dural venous sinuses

Question 6

Describe the two layers of the dura

Answer 6

Periosteal - layer fuses with periosteum lining the inner table of the skull -> considered to be the periosteum

Meningeal - adjacent to arachnoid. Is continuous with the spinal cord - periosteal layer is not

Question 7

Name the dural folds

Answer 7

Falx cerebri - dural fold that sits between hemispheres. Goes from the front to the back

Tentorium cerebelli - dural fold that tents over the posterior cranial fossa. Is horizontal

Question 8

What are the functions of the dural folds

Answer 8

Help stabilise the brain and act as rigid dividers

Prevent side to side movement of the brain

Question 9

What can dural folds cause if there is an increase in intracranial pressure

Answer 9

Dural folds can cause compression of the brain

Can cause herniation - displacement of parts of the brain through dural folds and/or through foramane magnum