Bales: Ventricles, CSF, meninges

Question 1

In a horizontal section, where would you find the trigone?

Answer 1

It is a small triangle behind the thalamus

Question 2

In coronal sections, what part of the lateral ventricles will be seen and what will it look like in an anterior cross section? middle? at the level of the trigone?

Answer 2

anterior: only the anterior horn of the lateral ventricles will be seen shaped like a butterfly (there won’t be temporal horn because it is too anterior)

further back: the body of the ventricles will be seen (hawk wings) and the small temporal horn

at the trigone, there is one large chamber

Question 3

What separates the anterior horns of the lateral ventricles? What can happen to this in boxers and people who undergo trauma?

Answer 3

the septum pellucidum (two sheets with a cavem septii pellucidi space in between them)

the septum can perforate, allowing the CSF to flow throughout this area

Question 4

What are the openings around the 3rd ventricle?

Answer 4

the inter ventricular foramen is anterosuperior to the 3rd ventricle (connects the lateral ventricle to the 3rd)

the opening to the cerebral aqueduct is posteroinferior

the 3rd ventricle is midline, next to the thalamus. it becomes very thin as the hypothalamus comes together (about a quarter)

Question 5

Where is the cerebral aqueduct found? What surrounds it?

Answer 5

between the midbrain tectum and tegmentum (connects the 3rd and 4th ventricles)

it is surrounded by periaqueductal gray matter

Question 6

Where is the 4th ventricle located? How many openings are in the 4th ventricle?

Answer 6

4th ventricle lies posterior to pons and rostral medulla, covered by the cerebellum

5 openings:

• 2 lateral foramen of luschka
• 1 median foramen of megendie
• 1 superior from the cerebral aqueduct
• 1 inferior to the central canal

luschka and megendie go to the subarachnoid system

Question 7

Where can the choroid plexus be found?

Answer 7

1. lateral ventricle - temporal horn roof
2. lateral ventricle - trigone anterior wall
3. lateral ventricle - body floor
4. interventricular foramen
5. 3rd ventricle roof
6. inferior 4th ventricle roof (inferior medullary velum)

Question 8

what kind of cells line the ventricular system?

Answer 8

simple cuboid epithelium

the choroid plexus has secretory ependyma surrounding leaky (fenestrated) capillaries

Question 9

Where are leaky capillaries found in the brain?

Answer 9

in the choroid plexus and in circumventricular organs (CVOs) which are normally sensory or secretory

Question 10

What are the CVOs?

Answer 10

1. organum vasculosum of lamina terminalis (OVLT)
   - -> important in hypothalamus regulation
2. median eminence
3. subcommissural organ
4. subfornical organ
5. pineal gland
6. area postrema

Question 11

What condition can develop as a result of ependymoma in the 4th ventricle?

Answer 11

The ventricular lining may become tumorous (ependymoma). A common site is the 4th ventricle floor . This growth can plug the system at the 4th and 3rd ventricles causing hydrocephalus.

Question 12

What can result if there is a neoplasm of the choroid plexus epithelium?

Answer 12

there is an increase in surface area and in increase in CSF production–> hydrocephalus from overproduction

Question 13

What is the difference in meningeal layers affected in meningitis vs. encephalitis?

Answer 13

Meningitis involves cellular arachnoid and pia, aided by subarachnoid spread.

Encephalitis involves brain matter

Question 14

what are some characteristics of a epidural hematoma?

Answer 14

above (outside) dura; between dura & bone

often caused by a tear in the middle meningeal a. ; high pressure

hemorrhage may cross a falx - can’t follow sulci

often lens-shaped

Question 15

what are some characteristics of a subdural hematoma?

Answer 15

between dura & arachnoid mater

often from tears in the bridging vv. ; low pressure

hemorrhage doesn’t cross falx - doesn’t fill sulci

produces a longer, flatter bleed than the epidural (low pressure)

Question 16

what are some characteristics of a subarachnoid hemorrhage?

Answer 16

occurs between arachnoid mater and pia mater.

High pressure cerebral aa. fill subarachnoid space easily.

Blood doesn’t cross falces, but does follow sulci.

Question 17

What are cisterns?

Answer 17

large, expanded subarachnoid spaces

Question 18

What lies in the superior cistern?

Answer 18

the great cerebral vein of Galen

Question 19

What passes through the interpeduncular cistern?

Answer 19

CN III

Question 20

Where does the foramen of Luschka drain CSF into? what about foramen of magendie?

Answer 20

Luschka drains into pontine cistern

Magendie drains into the cisterna magna

Question 21

What can cause non-communicating hydrocephalus?

Answer 21

non-communicating hydrocephalus: ventricles not freely interconnected

Obstruction at foramen of Monroe or cerebral aqueduct (from midbrain compression) enlarges upstream ventricles ; 4th ventricle doesn’t enlarge –> mickey mouse ventricles

this will stretch the corpus callosum

Question 22

What can unilateral enlargement of a lateral ventricle suggest?

Answer 22

obstruction of an inter ventricular foramen–> parasite?

Question 23

What can cause communicating hydrocephalus?

Answer 23

interventricle communications open

Obstruction of subarachnoid space or return at arachnoid granulations backs up CSF through Luschka and Magendie (enlarges ALL ventricles)

Question 24

What is the “glymphatic” system?

Answer 24

Pia mater initially accompanies penetrating vessels forming paravascular spaces

CSF bulk flow through interstitial spaces to or from paravascular spaces (possibly aided by glia) is informally called the “glymphatic” system