Dural Venous Sinuses

Question 1

Functions of the meninges

Answer 1

Separate soft tissue of brain from cranium
Protect blood vessels that supply brain
Contain and circulate CSF
Parts of the meninges form some veins that drain blood from brain

Question 2

Draw the layers of the meninges

Answer 2

Refer to drawings

Question 3

Meningeal and Periosteal layers

Answer 3

Meningeal layer is usually fused with periosteal layers, except in areas where two layers separate to from large blood filled spaces called the dural venous sinuses

Question 4

Draw the layers of the dura including the dural venous sinus, emissary and bridging veins

Answer 4

Refer to drawings

Question 5

How are dural venous sinuses different from veins?

Answer 5

Dural sinuses are more like spaces that contain venous blood.

Question 6

Emissary v.

Bridging v.

Answer 6

• drains blood from the scalp to the dural venous sinus

- drains blood from the cerebral cortex to the dural venous sinus

Question 7

Arachnoid mater properties

Answer 7

Partially composed of web of collagen elastic fibers (arachnoid trabeculae)
Space between the dura and arachnoid is the subdural space/potential space (not normally there, unless something is wrong)
Deep to the arachnoid is the subarachnoid space

Question 8

Potential causes of existence of subdural space between the dura and arachnoid mater?

Answer 8

• bleeding from the bridging v.
• following a lumbar puncture, CSF is taken from the subarachnoid space , creating negative pressure and creating the separation

Question 9

Are there arteries in the subarachnoid space?

Answer 9

Yes. Aneurysms in these cerebral arteries can rupture and cause bleeding in the subarachnoid space (main causes are artery wall weakening or hypertension)

Question 10

Describe the formation of the cranial dural septa and its function

Answer 10

Meningeal layer extends downward to form an opening, called the cranial dural septa. This is basically a membrane that separates the hemispheres of the brain
Function is to help stabilize and support the entire brain

Question 11

Four important septa:

Answer 11

Falx cerebri
Tentorium Cerebelli
Falx cerebelli
Diahragma sellae

Question 12

Draw the four cranial dural septa

Answer 12

Refer to drawings

Question 13

What does each septum separate?

Answer 13

Falx cerebri - two halves of the cerebrum
Falx cerebelli - two halves of the cerebellum
Tentorium cerebelli - cerebrum from cerebellum
Diaphragma sellae - forms the roof of the pituitary fossa

Question 14

Draw the arterial supply to the meninges:

Answer 14

Refer to drawings

Question 15

What is the main blood supply to the meninges?

What foramen does it pass through?

Answer 15

Middle meningeal artery

Foramen spinosum

Question 16

Draw the innervation of the meninges

Answer 16

Refer to drawings

Question 17

Middle meningeal a. rupture

Answer 17

Artery courses between the skull and the dura mater. Rupture causes bleeding between the skull and the dura (epidural space), causing epidural hematoma

Question 18

Where are you most likely to get an epidural hematoma?

Answer 18

Pterion, junction of the temporal, parietal and occipital bone. Suture junction makes it a weaker spot and skull here is thinner. Anterior branch of the middle meningeal a. is right at the pterion, so trauma here is more susceptible to artery rupture

Question 19

Bridging vein rupture

Answer 19

Subdural hemorrhage, bleeding creates a potential space between the dura and arachnoid.
Common in elderly who suffer acceleration/deceleration injury or Shaken baby syndrome

Question 20

Aneurysm rupture

Answer 20

-Blood vessels in the subarachnoid space can form aneurysms and rupture causes bleeding into the subarachnoid space.
-Can also happen after a lumbar puncture
Clinically: severe headache (worst headache of life), vomiting, photophobia

Question 21

Sigmoid sinus drains down and becomes the …

Answer 21

Internal jugular v.

Question 22

Significance of the superior ophthalmic, inferior ophthalmic and facial veins?

Answer 22

Located on the face and connected to the cavernous sinus. Infection in the face can spread to the cavernous sinus

Question 23

Significance of the superior and inferior petrosal sinuses:

Answer 23

Thecavernous sinus drainsby these two channels ultimately into the internal jugular vein via the sigmoidsinus

Question 24

Where is the cavernous sinus located?

Answer 24

Paired cavities that side on either side of the sphenoid bone, drains venous blood from the vein to the internal jugular v.

Question 25

What are the contents of the Cavernous sinus?

Answer 25

Vessels: internal Carotid A.
Nerves: CN III, IV, VI, V1, V2

Question 26

Draw the Path of the Internal carotid artery as it enters the brain and branches into the cerebral arteries

Answer 26

Refer to drawings

Question 27

Cavernous Sinus thrombosis

Answer 27

Since there are a lot of cranial nerves in the cavernous sinus, infection in this area (or in the face, where the veins are connected to the cavernous sinus) can lead to various symptoms depending on the affected nerves
Clinical: high fever, periorbital edema and chemosis, cranial nerve palsies (most commonly CN VI), decreased visual acuity

Question 28

Functions of CSF:

Answer 28

• buoyancy
• protection
• environmental stability

Question 29

How is the CSF formed?

Answer 29

Choroid plexus (blood vessels) in the ventricle. Ependymal cells here secrete fluid from their blood plasma. Fluid flows from the choroid plexus and around the brain 
Composition is more Na+, H+ and Ca2+, less potassium

Question 30

Describe the drainage of the CSF?

Answer 30

Drains via the arachnoid granulation > to the Dural venous sinuses > internal jugular v.
-drainage system prevents clogging of the CSF in the brain

Question 31

Subarachnoid hemorrhage and Arachnoid granulations:

Answer 31

Arachnoid granulations can be damaged by blood as it mixes with the CSF. The granulations fibrose and limits their ability to drain the CSF properly.

Question 32

Hydrocephalus

Answer 32

Ineffective drainage of the CSF causes clogging in the brain, causing compression and shrinkage of the brain and enlargement of the ventricles.
Clinically presents as enlarged head