Meninges, Blood supply, Ventricles and Sinuses

Question 1

Name the meningeal layers from top to bottom

What are the characteristics of the main 3

Answer 1

Dura mater (with venous sinus in between)

• periosteal layer
• meningeal layer

Subdural space (potential space for subdural bleeds)

Arachnoid mater
Subarachnoid space

Pia mater

Dura mater

• visible collagenous protective layer
• innervated by meningeal branch of V1(tentorial), V2, V3, X, C2-3

Arachnoid mater
-delicate, non vascular tissue

Pia mater

• continuous with brain, SC surface
• forms CSF with ependymal cells
• invisible to the naked eye

Question 2

Where do the meninges extend to

Answer 2

From brain => S2

even though the SC ends at L1

Question 3

Name the main 3 meningeal partitions
What are the attachments
What sinuses are associated with each one
What pathology is associated with one

Answer 3

Protects inner surfaces of the brain

Falx cerebri

• between cerebral hemispheres, attaches to crista galli => tentorium cerebelli
• upper margin contains SSS

Falx cerebelli
-between cerebellar hemispheres, attaches from int occipital crest => bifurcates around foramen magnum

Tentorium cerebelli

• between occipital and cerebellar hemispheres
• lined by transverse sagittal sinus
• tentorial herniation compresses III

Question 4

Describe the mechanism and likely cause of a subdural bleed

What are the symptoms
What would you see on a brain CT

Answer 4

Trauma of bridging vein between arachnoid and dura => crescent sign on CT

Can be acute or chronic

• Headache that worsens
• nausea, confusion, mood swings
• LOC, death

Question 5

Describe the mechanism and likely cause of a subarachnoid bleed

What are the symptoms
What would you see on a brain CT

Answer 5

Arterial bleed of the CofW => arachnoid space => blood in sulci, gyri

• thunderclap headache
• stiff neck, stroke like
• LOC, death

Question 6

Describe the mechanism and likely cause of an extradural bleed

What are the symptoms
What would you see on a brain CT

Answer 6

Trauma to MMA, branch of the maxillary, from ECA => lentiform sign

• LOC => lucid with headache => LOC (mass effect of blood => coning, compressing resp centers)
• contralateral hemiparesis
• confusion, N+V

Question 7

Describe the route of the anterior supply of the brain

Answer 7

ICA from aortic arch => carotid canal in petrous part =>

• ACA
• MCA
• opthalmic
• central artery of retina

Question 8

Describe the route of the posterior supply of the brain

Answer 8

Subclavian => vertebral via transverse foramen => foramen magnum => lateral of medulla => fuse to form basilar on ventral pons

• PCA
• SCA
• AIC
• PIC

Question 9

Describe the location of the Circle of Willis

Answer 9

ICA emerges lateral to sphenoid body => adjacent to optic chiasm

Optic chiasm which wraps around the pituitary

Basilar ventral to pons

Question 10

What is the dural venous sinus
-what are the main properties

Describe the route from the SSS
Describe the route from the ISS and great cerebral vein

Answer 10

Between dural layers
No valves, from brain and cavity => internal jugular

SSS => RTS => R sigmoidal => R IJV

ISS and great cerebral vein=> straight => LTS => L sigmoidal => L IJV

Question 11

What is the cavernous sinus

What structures can you find here

Answer 11

Lateral to pituitary in sphenoid fossa

Medially
-ICA surrounded by SNS plexus

Laterally
-III, IV, V1, V2, VI

Cavernous sinus surrounds all these structures

Question 12

What drains into the cavernous sinus

Why is this clinically important

Answer 12

Opthalmic
Superficial middle cerebral
Sphenoparietal sinus

Cavernous sinus => petrosal sinus => internal jugular

Cavernous sinus thrombosis

• follows infection of teeth, sinus, eye, noses => valveless veins
• cavernous sinus significant in spread

Question 13

Describe the route taken by the CSF

What structure produces CSF

Answer 13

Lateral ventricles => 3rd => aqueduct => 4th => apetures => cisterna magna in subarachnoid => reabsorbed via arachnoid granulations into veins

CSF produced by choroid plexus

Question 14

Where are the 4 types of sinus
What is their function

What is the clinical function that links CSF and sinuses

Answer 14

Frontal
Ethmoid
Sphenois
Maxilla

Make skull lighter, improve vocal quality
Produce mucus to protect nose

CSF rhinorrhea => fracture of the sinus/cribriform plate => disruption of skull, subarachnoid and dura

Question 15

What is assoicated with the

• foramen spinosum
• foramen lacerum
• carotid canal
• IAM
• jugular foramen
• foramen magnum

Answer 15

Foramen spinosum => MMA

Foramen lacerum => can see ICA

Carotid canal => ICA

IAM =>VII, VIII, labyrinthine artery

Jugular foramen => IX, X, XI, inf petrosal sinus, sigmoid sinus

Foramen magnum => medulla at clivus, vertebral arteries, meninges, CSF, XI