Veins of the brain, Arachnoid and Pia Matter and Spinal Meninges

Question 1

Describe the course of veins of the brain?

Answer 1

• Delicate venous drainage from the cerebral hemispheres emerges from the brain to form small venous structures in the pia mater
• These larger venous channels then form cerebral veins, which bridge the subarachnoid space and enter into endothelial-lined sinuses within the dura mater

Question 2

Describe general characteristics of veins of the brain?

Answer 2

1. Possess no valves
2. Have extremely thin walls
3. Pierce the arachnoid membrane and the inner or meningeal layer of the dura mater, and open into the cranial venous sinuses

Question 3

What are the 2 types of veins of the brain?

Answer 3

1. cerebral
2. cerebellar

Question 4

Cerebral veins are divided into which 2 groups?

Answer 4

1. Superficial (External group) (Superior, middle and inferior cerebral veins)
2. Deep (Internal) group

Question 5

Describe the drainage of the superior cerebral veins?

Answer 5

Drain into the superior sagittal sinus

Question 6

Describe the drainage of the middle cerebral vein?

Answer 6

Drains in the cavernous sinus

Question 7

The middle cerebral vein is connected with?

Answer 7

1. the superior sagittal sinus by the great anastomotic vein of Trolard > which opens into one of the superior cerebral veins
2. the transverse sinus by the posterior anastomotic vein of Labbé > which courses over the temporal lobe.

Question 8

Describe the drainage of the inferior cerebral vein?

Answer 8

Drain in the superior sagittal sinus, cavernous, sphenoparietal, and superior petrosal sinuses

Question 9

Function of superior anastomatic vein?

Answer 9

connect superficial middle cerebral vein with the superior sagittal

Question 10

Function of inferior anastomotic vein?

Answer 10

connects the superficial middle cerebral vein with the transverse sinus

Question 11

Name the deep cerebral veins and what they drain?

Answer 11

1. thalamostriate
2. choroidal
   > drain internal structures of the forebrain
   - basal ganglia
   - thalamus
   - internal capsule
   - choroid plexus
   - hippocampus

Question 12

Describe the course of the deep cerebral veins?

Answer 12

thalamostriate + choroidal veins = 2 internal cerebral veins
2 internal cerebral veins unite = great cerebral vein
> unite in midline
> lies beneath the splenium of the corpus callosum and drains the deep structures of the forebrain
Note: great cerebral vein is continuous with the straight sinus which lies in the midline of the tentorium cerebelli

Question 13

Describe the drainage of the cerebral veins the dural venous sinuses?

Answer 13

1. superior cerebral veins > superior sagittal sinus
2. great cerebral vein > inferior sagittal sinus + joins with it to form straight sinus
   > dural venous sinuses are connected to extracranial veins via emissary veins

Question 14

Describe the consequences of cerebral damage caused by venous infarction?

Answer 14

manifests as epleptic attacks and focal paralysis of the limbs

Question 15

Describe the arterial supply to the dura mater?

Answer 15

1. Middle meningeal arteries – branch of maxillary artery
   > supply the lateral surface
2. Ophthalmic artery
   > branches supply the anterior surface
3. Occipital and vertebral arteries
   > branches supply the posterior surface

Question 16

Describe the nerve supply to the dura mater?

Answer 16

1. Trigeminal nerve – except the posterior fossa.
2. Posterior fossa is supplied by Vagus nerve and 2nd and 3rd cervical nerves
   > Dura mater is pain sensitive as well as proximal portions of blood vessels at the base of the brain.
   > Dural nerves follow arteries and terminate near arteries or venous sinuses

Question 17

Describe the innervation of the anterior cranial fossa?

Answer 17

1. meningeal branch of the ophthalmic nerve [V1]
   - turns and runs posteriorly
   - supplying the tentorium cerebelli and the posterior part of the falx cerebri.
2. meningeal branches from the ethmoidal nerves
   - which are branches of the ophthalmic nerve [V 1 ]
   - supply the floor and the anterior part of the falx cerebri.

Question 18

Describe the innervation of the middle cranial fossa?

Answer 18

1. supplied medially by meningeal branches from the maxillary nerve [V2]
2. Supplied laterally, along the distribution of the middle meningeal artery, by meningeal branches from the mandibular nerve [V3]

Question 19

Describe the innervation of the posterior cranial fossa?

Answer 19

1. supplied by meningeal branches from the first, second, and, sometimes, third cervical nerves, which enter the fossa through the foramen magnum, the hypoglossal canal, and the jugular foramen
2. Meningeal branches of the vagus nerve [X] have also been described.
   Note: Possible contributions from the glossopharyngeal [IX] and hypoglossal [XII] nerves have also been reported.)

Question 20

What is the arachnoid mater?

Answer 20

Is a thin avascular membrane composed of few layers of cells
> Bundles of collagen interspace the membrane.
> Outermost layer adheres to the inner surface of the dural mater and contains no collagen

Question 21

Describe the components of the arachnoid mater?

Answer 21

1. Arachnoid trabecularae > extend to pia mater and help to suspend the brain.
   > Arachnoid does not dip into the sulci –hence creates a subarachnoid space between arachnoid and pia mater.
2. Subarachnoid space > filled with Cerebrospinal fluid (CSF)

Question 22

What are subarachnoid cisterns?

Answer 22

spaces formed by openings in the subarachnoid space
> filled with CSF

Question 23

Name the major subarachnoid cisterns?

Answer 23

1. Cerebelomedullary cistern (Cistern magna )- between the inferior surface of the cerebellum and posterior to medulla
2. Pontine cistern - anterior surface of the pons and medulla
3. Interpeduncular cistern – between cerebral peduncles
4. Superior cistern (Quadrigeminal cistern)
5. Cistern of the great cerebral vein

Question 24

What are arachnoid villi and describe their function?

Answer 24

• Major sites for reabsorption of CSF into the venous system.
• CSF enters the venous circulation through arachnoid villi
• Arachnoid villi penetrate the dural layer at certain dural venous sinuses
  > more common in the superior sagittal venous sinuses
• Large number of villi form arachnoid granulations

Question 25

What is the pia mater?

Answer 25

• Delicate membrane that covers the surface of the CNS
• Follows the gyri and sulci of the brain
• Cerebral arteries and veins travel in subarachnoid space held against the pia by connective tissue

Question 26

Name the cranial Meningeal spaces and what vessels are contained within them?

Answer 26

1. Epidural space = Meningeal arteries
2. Subdural space = dural veins
3. Subarachnoid space = cerebral arteries and CSF

Question 27

Describe spinal meninges?

Answer 27

The spinal meninges (dura mater, arachnoid mater, and pia mater) are layers of connective tissue that protect the spinal cord and supply it with nutrients
- They are continuous with the cranial meninges, which perform the same functions for the brain
- Between the arachnoid mater and the pia mater is the subarachnoid space, which contains cerebrospinal fluid (CSF)

Question 28

Describe the dura mater of the spinal cord?

Answer 28

1. Spinal dura has one layer
   > The spinal dura does not have an outer: endosteal layer
2. Vertebral canal contains actual spinal epidural space
3. spinal epidural space is located between the periosteum and dural

Question 29

Where does the spinal cord terminate?

Answer 29

L1 - L2

Question 30

Describe the course of the meninges of the spine?

Answer 30

• The spinal cord terminates at
  level L1-L2
• The dura and arachnoid and, subarachnoid space, continue caudally to S2 > forming dural sac
• Below L2, the pia mater extends downwards forming the filum terminale which pierces the arachnoid and dural sacs and passes through the sacral hiatus to be attached to the back of the
  соссух.

Question 31

What is the spinal dural sac and it’s function?

Answer 31

Spinal dural sheath ends at
2nd sacral vertebrae (S2) while spinal cord ends between L1 and L2 creating a lumbar cistern (L1 - S2)
= (dural sac)
- site for CSF sampling

Question 32

Describe the pia mater of the meninges of the spinal cord?

Answer 32

• Thick and contains toothed longitudinal ligaments (dentate (denticulate) ligament
• Anchors spinal cord to dura
• Contains filum terminale to anchor the spinal cord to caudal end

Question 33

Describe the clinical correlates of Meningeal spaces and arteries?

Answer 33

1. Bleeding can open up potential meningeal spaces
2. Tearing meningeal arteries can cause an Epidural hematoma
3. Tearing of veins entering venous sinuses can cause subdural hematoma

Question 34

What is a spinal hematoma?

Answer 34

Collection of blood that compresses the spinal cord and nerve roots