Meninges

Question 1

What are the three layers on the meninges?

Answer 1

Dura Mater
Arachnoid Mater
Pia Mater

Question 2

What do the meninges cover?

Answer 2

the brain and spinal cord

Question 3

What are the characteristics of the dura mater?

Answer 3

outermost, thickest, protective, impermeable

Question 4

What are the 2 layers of the dura mater?

Answer 4

periosteal layer
meningeal layer

Question 5

Where is the periosteal layer of the dura mater?

Answer 5

continuous with periosteum on the outside of the skull and cranial sutures

Question 6

Where is the meningeal layer of the dura mater?

Answer 6

penetrates spaces in the cerebral hemisphere

Question 7

The layers of the dura mater are closely united except for where?

Answer 7

at the venous sinuses

Question 8

What are the venous sinuses?

Answer 8

large, low-pressure blood vessel return path for cerebral venous blood

Question 9

What 2 partitions arise from the meningeal layer of the dura mater?

Answer 9

falx cerebri
tentorium cerebelli

Question 10

What is the falx cerebri?

Answer 10

sickle-shaped fold separating cerebral hemispheres

Question 11

Where is the tentorium cerebelli located?

Answer 11

between cerebellum and occipital lobes, separates the posterior cranial fossa from the cranial vault

Question 12

How does the falx cerebri form the sagittal sinus?

Answer 12

superior convex border forms the superior sagittal sinus
inferior border houses the inferior sagittal sinus

Question 13

How is the venous sinus formed?

Answer 13

Tentorium cerebelli arches upward along the median line to become continuous with the falx cerebri to form straight venous sinus

Question 14

What is the function of the falx cerebri and the tentorium cerebelli?

Answer 14

restrict brain displacement associated with acceleration and deceleration

Question 15

What is the epidural space?

Answer 15

tight space between the dura and the skull

Question 16

What is the usual cause of an epidural hematoma/hemorrhage?

Answer 16

rupture of the middle meningeal artery during a head trauma

Question 17

What are the symptoms of an epidural hematoma/hemorrhagic?

Answer 17

none initially (lucid interval)
within hours compresses the brain, increases ICP, herniation, and death unless surgery

Question 18

What is the subdural space?

Answer 18

between the dura and loosely adherent arachnoid

Question 19

What is the usual cause of a subdural hematoma/hemorrhage?

Answer 19

rupture of bridging veins (vulnerable to shear injury)

Question 20

How can an acute subdural hematoma/hemorrhage occur?

Answer 20

with high-velocity impact

Question 21

What is a chronic subdural hematoma/hemorrhage?

Answer 21

slow bleeding over weeks/months (brain accommodates)
vague symptoms - headache, cognitive impairment, unsteady gait

Question 22

What are the 2 types of chronic subdural hematoma/hemorrhage?

Answer 22

isodense - 1-2 weeks
hypodense - 3-4 weeks (typically elderly due to natural atrophy that decreases the stability of the brain - bridging vein)

Question 23

What are the characteristics of the arachnoid mater?

Answer 23

middle, impermeable

Question 24

what are the trabeculae?

Answer 24

delicate threads connecting the arachnoid to the pia

Question 25

What are the arachnoid granulations?

Answer 25

The site where CSF diffuses into venous sinuses

Question 26

What is in the subarachnoid space?

Answer 26

all arteries/veins send branches that penetrate the brain filled with CSF

Question 27

What are the characteristics of the pia mater?

Answer 27

innermost, delicate, permeable, resting on the brain surface vascular membrane

Question 28

How is the choroid plexus formed?

Answer 28

pia mater fuses with ependyma

Question 29

What do arteries carry as they enter the parenchyma?

Answer 29

a sheath of pia

Question 30

Are there pain receptors in the brain?

Answer 30

no

Question 31

Where does head pain come from?

Answer 31

the trigeminal and first three cervical nerves innervating the meninges and vasculature

Question 32

What does the trigeminal ganglion innervate?

Answer 32

dura above the tentorium

Question 33

What do the first 3 cervical nerves innervate?

Answer 33

dura below the tentorium

Question 34

Are the meninges densely innervated?

Answer 34

yes very

Question 35

What is a migraine headache?

Answer 35

activation of trigeminal afferents that densely innervate meninges

Question 36

What is the proposed mechanism for a migraine headache?

Answer 36

cortical spreading depression event - ions released activate pain receptors and vasodilators released (CGRP) further activate pain fibers *cycle

Question 37

What is meningitis?

Answer 37

inflammation of meninges

Question 38

What are meningiomas?

Answer 38

tumours in the meninges (usually benign)

Question 39

How does a space-occupying lesion cause pain?

Answer 39

increased ICP and stretching of dura

Question 40

What is a cluster headache?

Answer 40

'lancinating' or 'boring' periorbital pain maybe the most painful condition known

Question 41

What is a hangover?

Answer 41

multifactorial a toxic effect on meninges

Question 42

How do immune cells act in the meninges?

Answer 42

potentially decreased activation threshold for pain fibres recruitment of immune cells to the injury site some benefit, but a potential cost