Meninges And Dural Venous Sinuses Flashcards
What are the meninges?
3 membranous layers surrounding the brain and spinal cord
What are the 3 layers of the meninges (Innermost to outermost)
- Pia Mater: Firmly attached to surface of brain
- Arachnoid Mater: Delicate avascular middle layer
- Dura Mater: Tough outer layer, made up of 2 layers
What are the bumps and dips of the brain called? Which meningeal layer follows these contours?
Bumps- Gyri
Dips- Sulci
Pia Mater
Describe the arachnoid mater’s relationship to Pia Mater
- Superficial to Pia Mater
- Trabeculae extend downward from its inner surface and become continuous with Pia Mater
What is the region between the Arachnoid and Pia mater?
What is it full of?
Sub-arachnoid space
Full of CSF, veinous and arterial blood vessels
What does the term Leptomeninges mean?
Combined term for Pia and Arachnoid mater
The Dura Mater consists of 2 layers.
Compare them
Outer Periosteal;
- Firmly attached to skull
- Contains meningeal arteries
- Continuous with periosteum on outer surface of skull
- Not continuous with spinal dura matter through Foramen magnum
Inner Meningeal;
- Continuous with spinal dura mater through foramen magnum
Describe the relationship between the Inner Dural layer and Arachnoid Mater
What is the clinical significance of this?
Arachnoid Mater pushed up against Inner Meningeal Layer by CSF
Forms the Subdural space (a potential space)
What does the Arachnoid Mater look like
Translucent
What are 2 types of locations where the 2 layers of the dura mater separate from each other?
- Dural venous sinuses (blood between 2 layers)
- Dural partitions/ folds, which project inwards and incompletely separate parts of brain
What is the Extradural space?
A potential space between dura mater and bone
Can fill with blood from a meningeal artery rupture or torn Dural venous sinus
Name 4 Dural Folds
- Falx Cerebri (Vertical)
- Tentorum Cerebelli (Horizontal)
- Falx Cerebelli
- Diaphrgam Sellae
What is the Falx Cerebri?
- A crescent shaped downward projection of meningeal dura mater, that separates the left and right hemisphere
Name the attachments of the Falx Cerebri
Anterior: Crista Galli of ethmoid bone (and frontal crest of frontal bone)
Posterior: Blends with Tentorum Cerebelli
What is the Tentorum Cerebelli?
- A horizontal projection of meningeal dura mater, that separates the Cerebellum from the posterior parts of the cerebral hemispheres
What are the attachments of the Tentorum Cerebelli?
Posteriorly: Occipital bone along grooves of Transverse Sinuses
Laterally: Superior border of Petrous part of Temporal bone
Describe the Anterior and Medial borders of Tentorum Cerebelli
Are free, forming an oval opening in the midline (The Tentorial Notch), through which midbrain passes
What do the Dural Folds do? (In general)
- Help to stabilise brain and act as rigid dividers
Considering the Dural Folds, what can happen when intra-cranial pressure rises?
(Such as due to a bleed)
Can lead to compression/ herniation of parts of brain against the Dural Folds or Through Foramen Magnum
(Can lead to mental consequences)
What connects the back of the Inferior Saggital Sinus to the Superior Saggital Sinus before it branches off into Transverse sinuses?
Straight Sinuses
What is the Inferior Petrosal Sinus?
Connects posterior Cavernous Sinus to Sigmoid Sinus, just before SS leaves skull base
What is the Superior Petrosal Sinus?
Connection between posterior Cavernous Sinus and Transverse Sinus, just before TS becomes Sigmoid Sinus
What are Bridging and Emissary Veins
Bridging: Connect Dural Veinous Sinuses to Cerebral Veins
Emissary: Connect Dural Veinous Sinuses to Scalp Veins (This is how scale infections can enter skull)
What are the 3 spaces between the meningeal layers where blood can accumulate
Where else can bleeding occur?
How?
- Extradural (Bone and Dura)
- Subdural (Dura and Arachnoid)
- Subarachnoid (Arachnoid and Pia)
- Within the brain tissue itself (Intra-cerebral haemorrhage)
- Contusions, tearing of white matter etc.
