KMS - Lecture 8 & 9 - Cranial Meninges

Question 1

What are the layers, starting with cerebral cortex, of the meningeal layers?

Answer 1

Cortex/brain cells
Pia mater
Subarachnoid space with arachnoid trabeculae
Arachnoid
Dura layer

Question 2

What tissue makes up pia mater?

Answer 2

Areolar CT

Question 3

How are the tissues different between pia and arachnoid mater?

Answer 3

Arachnoid has somewhat more dense CT layer than pia - more elastic and collagen fibers

Question 4

What forms the subarachnoid space? What are the contents?

Answer 4

Trabeculated deep surface of arachnoid mater

Contains CSF, cerebral aa and veins

Question 5

What covers the brain? What dips into sulci?

Answer 5

Pia - covers, dips into sulci, invests vessels
Arachnoid - covers, doesn’t dip into sulci except for longitudinal fissure
Dura - covers, doesn’t dip into sulci - forms reflections

Question 6

What forms cisterns?

Answer 6

Cisterns = areas of accumulated CSF

- formed by arachnoid mater and contours of the brain

Question 7

What forms CSF (cerebrospinal fluid)?

Answer 7

Choroid plexus

- modified tuft of capillaries in the ventricles

Question 8

How does CSF get into the sub-arachnoid space?

Answer 8

CSF flows through ventricles to 4th ventricle

- openings then communicate with sub-arachnoid space

Question 9

Where is CSF reabsorbed? What structure is involved?

Answer 9

Into the superior sagittal sinus via arachnoid granulations

Question 10

What tissue is the dura mater? What is it continuous with?

Answer 10

Dense fibrous CT layer enclosing brain

- continuous with spinal dura at foramen magnum

Question 11

What is the periosteal layer of dura?

Answer 11

periosteum of cranial vault adherent to meningeal dura

Question 12

What is the meningeal layer of dura? What do they form?

Answer 12

duplications of dura - prolonged between major portions of the brain
- form dural reflections

Question 13

What meningeal layer eventually fuses with neural sheaths?

Answer 13

Dura mater - prolonged along cranial nerves

Question 14

Name the 4 dural reflections.

Answer 14

Falx Cerebri
Tentorium Cerebelli
Falx Cerebelli
Diaphragma Sellae

Question 15

What sinuses are in the falx cerebri?

Answer 15

Superior sagittal sinus

Inferior sagittal sinus

Question 16

What are the attachments and shape of the falx cerebri?

Answer 16

Anterior- crista galli of ethmoid
- forms a sickle shape between hemispheres
Posterior - continuous with tentorium cerebelli at internal occipital protuberance

Follows contour of sagittal suture in its course

Question 17

What forms a tent over the posterior cranial fossa? What separates cerebellum from posterior cranial hemispheres?

Answer 17

Tentorium cerebelli

Question 18

What sinuses does the tentorium cerebelli enclose?

Answer 18

Transverse sinuses

Superior petrosal sinuses

Question 19

Where does the tentorium cerebelli attach?

Answer 19

Anterior - ant. and post. clinoid processes of sphenoid bone

Periphery - occipital bone at grooves for transverse sinus

Question 20

What is the tentorial notch?

Answer 20

Free anterior concave margin of tentorium which wraps around midbrain

Question 21

Which dural reflection can kill you? How?

Answer 21

Tentorial notch on tentorium cerebelli

- can transect midbrain during rapid deceleration or loss of CSF

Question 22

What is the span of the falx cerebelli?

Answer 22

Extension of dura
Runs between cerebellar hemispheres
Runs from tentorium above to occipital crest below

Question 23

What does the falx cerebelli contain?

Answer 23

Occipital sinus

Question 24

What is the diaphragma sellae? What does it cover?

Answer 24

Specialized portion of dura

Forms roof over hypophyseal fossa