Bales: Ventricles, CSF, meninges Flashcards
In a horizontal section, where would you find the trigone?
It is a small triangle behind the thalamus
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?
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
What separates the anterior horns of the lateral ventricles? What can happen to this in boxers and people who undergo trauma?
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
What are the openings around the 3rd ventricle?
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)
Where is the cerebral aqueduct found? What surrounds it?
between the midbrain tectum and tegmentum (connects the 3rd and 4th ventricles)
it is surrounded by periaqueductal gray matter
Where is the 4th ventricle located? How many openings are in the 4th ventricle?
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
Where can the choroid plexus be found?
- lateral ventricle - temporal horn roof
- lateral ventricle - trigone anterior wall
- lateral ventricle - body floor
- interventricular foramen
- 3rd ventricle roof
- inferior 4th ventricle roof (inferior medullary velum)
what kind of cells line the ventricular system?
simple cuboid epithelium
the choroid plexus has secretory ependyma surrounding leaky (fenestrated) capillaries
Where are leaky capillaries found in the brain?
in the choroid plexus and in circumventricular organs (CVOs) which are normally sensory or secretory
What are the CVOs?
- organum vasculosum of lamina terminalis (OVLT)
- -> important in hypothalamus regulation - median eminence
- subcommissural organ
- subfornical organ
- pineal gland
- area postrema
What condition can develop as a result of ependymoma in the 4th ventricle?
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.
What can result if there is a neoplasm of the choroid plexus epithelium?
there is an increase in surface area and in increase in CSF production–> hydrocephalus from overproduction
What is the difference in meningeal layers affected in meningitis vs. encephalitis?
Meningitis involves cellular arachnoid and pia, aided by subarachnoid spread.
Encephalitis involves brain matter
what are some characteristics of a epidural hematoma?
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
what are some characteristics of a subdural hematoma?
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)
what are some characteristics of a subarachnoid hemorrhage?
occurs between arachnoid mater and pia mater.
High pressure cerebral aa. fill subarachnoid space easily.
Blood doesn’t cross falces, but does follow sulci.
What are cisterns?
large, expanded subarachnoid spaces
What lies in the superior cistern?
the great cerebral vein of Galen
What passes through the interpeduncular cistern?
CN III
Where does the foramen of Luschka drain CSF into? what about foramen of magendie?
Luschka drains into pontine cistern
Magendie drains into the cisterna magna
What can cause non-communicating hydrocephalus?
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
What can unilateral enlargement of a lateral ventricle suggest?
obstruction of an inter ventricular foramen–> parasite?
What can cause communicating hydrocephalus?
interventricle communications open
Obstruction of subarachnoid space or return at arachnoid granulations backs up CSF through Luschka and Magendie (enlarges ALL ventricles)
What is the “glymphatic” system?
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
