Lecture 5- Layers of the meninges, dural folds and venous sinuses

Question 1

the meninges is made up of

Answer 1

3 membranlous layers that surround and protect the braina nd spinal cord

Question 2

gyrae

Answer 2

bumps

Question 3

sulcae

Answer 3

dips

Question 4

fissues

Answer 4

big dip

Question 5

name the fissues

Answer 5

longintudinal and lateral

Question 6

layers of the meninges (from inner to outer)

Answer 6

Pia mater

Arachanoid

Dura mater

Question 7

pia mater characteritists

Answer 7

• Very thin, delicate adherent to surface of brain
• follows every dip and fold of the brain (covering all gyrae and sulcae)
• Wouldn’t be able to see or tease away from the brain (like visceral pleura)

Question 8

arachnoid mater characteristics

Answer 8

• Continuous surrounds brain and spinal cord
• Soft, fibrous translucent mem.
• Doesn’t extend down into the sulcae or lateral fissure
• Does extend down into the longitudinal fissure

Question 9

space between the arachnoid and pia mater

Answer 9

the subarachnoid space

• filled with CSF

Question 10

CSF in the subarachnoid space..

Answer 10

• Exerts a slight pressure separating layers
• Blood vessels from the vertebral and internal carotid artery for the brain are found in this plane (cerebral arteries and vein)

Question 11

Pia mater and the arachnoid referred to as the

Answer 11

leptomeninges- where infections like meningitis are found – can take sample of CSF for testing for infection of the meninges

Question 12

dura mater characteristics

Answer 12

• Tough fibrous membranate area
• Touches the arachnoid layer
  
  • Due to the pressure of the CSF under the arachnoid layer
• Not stuck together- so there is a potential space

Question 13

summary of the meninges

Answer 13

Question 14

dura is like a

Answer 14

two ply tissue

• Dura fuses with the periosteum lining inner table of skull bones

Question 15

dura has 2 layers within the skull which are stuck together

Answer 15

1. periosteal= part agaisnt the inner table- periosteum
2. meningeal= part adjacent to arachnoid

Question 16

the peiorsteal and meingeal layers of the dura are …

Answer 16

closely adhered- appearing a sa single layer

Question 17

althouhg periostela an dmenigeal layrrs are lcosely adhered , there are

Answer 17

areas where they are seperate. these separations forms :

• dural folds
• dural venous sinuses

Question 18

how are the dural fold and dural venous sinuses form

Answer 18

Meningeal layer of dura is peeled away from the periosteal layer to create the dural fold and dural venous sinuses

Question 19

the cavernous sinus is a

Answer 19

type of dural venous sinus in the cranial floor

Question 20

What is the function of the falx cerebri and the tentorium cerebelli?

Answer 20

The falx cerebri (or falx) is the largest dural folds- a scythe-shaped band of dura matter that separates a part of the cerebral hemispheres. Its inferior boundary is defined by the inferior sagittal sinus and straight sinus.

The tentorium cerebelli (plural: tentoria cerebellorum) is the second largest dural fold after the falx cerebri. It lies in the axial plane attached perpendicularly to the falx cerebri and divides the cranial cavity into supratentorial and infratentorial compartments 1. It has free and attached margins

Question 21

why do we have dural folds?

Answer 21

• Act as dividers- helping to stabilise the brain and act as rigid dividers

Question 22

dural folds and rise in pressure

Answer 22

A rise in pressure inside the skull e.g. secondary to a bleed can lead to compression and displacement (herniation) of parts of the brain against rigid dural folds (!-3) and/or through foramen magnum(4)

Question 23

Dural venous sinuses

Answer 23

Venous blood filled spaces created by separation of meningeal from periosteal layer of dura

• Found throughout the skull, surrounding the brain within areas where two layers of dura separate to create space
• Connected to each other- receive blood from cerebral veins (draining the brain)
• Drain into internal jugular vein

Question 24

dural venous sinuses anatomy

Answer 24

When the inferior sagittal sinus and superior sagittal sinus are connected by the straight sinus- to form the confluence of sinuses.

• Transverse sinuses extended laterally from the confluence
• Sigmoid sinuses when it bends into the jugular foramen and into the integral jugular veins
• Cavernous sinus- found in the middle cranial fossa
  
  • Connections between the 2 cavernous sinuses and the dural cavernous sinus system at the back for the skull
    
    • Connected by the petrosal sinuses

Question 25

Connections between the 2 cavernous sinuses and the dural cavernous sinus system at the back for the skull

Connected by…..

Answer 25

the petrosal sinuses

Question 26

Two important venous connections between the Dural venous sinuses and other venous structure- intracranially and extracranially

Answer 26

1. Cerebral veins- via bridging veins
2. Scalp veins – via emissary veins (has to pass through bone)

Question 27

• Bridging veins transverse subdural space

Answer 27

• Potential space between the dura and arachnoid (arachnoid is pushed up against it by pressure of CSF within subarachnoid space
• Should the bridging vein snap or collapse- intracranial haemorrhage

Question 29

Scalp veins connect with Dural venous sinuses

*

Answer 29

Emissary veins transverse through the skull

Question 30

image summary of venous sinuses

Answer 30