Old PBL

Question 1

What are the cranial meninges?

Answer 1

Membranous coverings of the brain that lie immediately internal to the cranium.

Question 2

What do the cranial meninges do?

Answer 2

• protect the brain
• form the supporting framework for arteries, veins and venous sinuses
• enclose a fluid filled cavity, the subarachnoid space, which is vital to the normal function of the brain

Question 3

What are the 3 membranous connective tissue laters that make up the cranial meninges?

Answer 3

1. Dura mater
2. Arachnoid mater
3. Pia mater

Question 4

What are the 2 layers of the dura mater?

Answer 4

1. External periosteal layer

2. Internal meningeal layer

Question 5

What is the calvaria?

Answer 5

Roof of the neurocranium

Question 6

What are the dural venous sinuses?

Answer 6

These are endothelium lined spaces found between the periosteal and internal meninges layer of the dura mater. They are responsible for the venous drainage of the cranium and empty into the internal jugular veins.

Question 7

What are dural reflections?

Answer 7

Formed when the meningeal layer of the dura mater folds in on itself and divide cranial cavity into compartments.

Question 8

What are the 4 dural reflections?

Answer 8

1. Falx cerebri
2. Tentorium cerebelli
3. Falx cerebelli
4. Diaphragma sellae

Question 9

Discuss the Falx cerebri

Answer 9

• largest dural infolding
• sickle shaped
• found in longitudinal cerebral fissure
• projects downwards to separate left and right cerebral hemispheres

Question 10

Discuss the Tentorium cerebelli

Answer 10

• second largest infolding of dura mater
• separates the occipital lobes from the cerebellum
• contains the tentorial notch - an anteromedial space for passage of the brain stem

Question 11

Discuss the Falx cerebelli

Answer 11

• vertical infolding of dura mater

- partially separates the right and left cerebellar hemispheres

Question 12

Discuss the diaphragma sellae

Answer 12

• smallest infolding of dura mater
• circular sheet of dura mater
• covers the hypophysial fossa of sphenoid bone
• contains a small opening for passage of the stalk of the pituitary gland

Question 13

Describe the vasculature and innervation of the dura mater.

Answer 13

Middle meningeal arteries and veins, trigeminal nerve (V1, V2 and V3)

Question 14

What is a haematoma?

Answer 14

A collection of blood

Question 15

What are the 2 types of haematoma involving dura mater?

Answer 15

1. Extradural: arterial blood collects between the skull and periosteal layer of the dura. The causative vessel is usually the middle meningeal artery, tearing as a consequence of brain trauma.
2. Subdural – venous blood collects between the dura and the arachnoid mater. It results from damage to cerebral veins as they empty into the dural venous sinuses.

Question 16

What 2 meningeal layers make up the leptomeninges? Where do they develop from?

Answer 16

• The arachnoid mater and pia mater.

- develop from a single layer of mesenchymal surrounding the embryonic brain

Question 17

Discuss the arachnoid mater.

Answer 17

• middle layer of the meninges
• made up of layers of connective tissue
• avascular
• no innervation

Question 18

Discuss the sub arachnoid space.

Answer 18

• located between the arachnoid and pia mater
• continuous with that of vertebral canal
  contains cerebrospinal fluid which acts to cushion the brain
• Bridged by trabeculae (irregularly shaped, flattened fibroblasts)
• Small projections of arachnoid mater into the dura (known as arachnoid granulations) allow CSF to re-enter the circulation via the dural venous sinuses.

Question 19

Discuss the pia mater.

Answer 19

• located deep to the sub arachnoid space
• very thin
• tightly adheres to surface of brain and spinal cord
• only covering to follow the fissures of the brain
• highly vascularised - blood vessels perforate the membrane to supply the underlying neural tissue