lecture 10 Flashcards
Ventricle of the Brain and CSF
where do the ventricles stem from?
neuronal canal gives rise to the ventricles of the adult brain
what are the ventricles filled with?
they are filled with CSF
how is the choroid plexus important to the ventricles?
The choroid plexus, which secretes the CSF that fills the ventricles and the subarachnoid space, arises from tufts of cells that appear in the wall of each ventricle during the first trimester.
how does the choroid plexus develop?
○ Arises from tufts of cells that appear in the wall of each ventricle during the first trimester
in the development of the choroid plexus, how does the choroid fissure develop?
Developing arteries in the immediate vicinity invaginate the roof of the ventricle to form a narrow groove
so inside the ventricular space, what represents the primordial choroid plexus, with respect to the development of the choroid plexus?
The involuted ependymal cells and blood vessels
as the development of the choroid plexus develops, what happens to the choroid plexus?
the choroid plexus enlarges → forms villi → secrete CSF
why is the end of first trimester important fo the choroid plexus?
it is functional, openings in the 4th ventricle are patent, CSF is circulating in the ventricular system and subarachnoid space
how is the choroid plexus in each ventricle represented?
into a series of folds called villi
describe the villi of the choroid plexus?
consists of a core of highly vascularized connective tissue derived from the pia mater and a simple cuboidal covering which is derived from ependymal cells.
how common are choroid plexus tumor?
rare, if they occur it will most likely be in the 4th ventricle
how does the shape of the ventricular system conform?
it conforms to the changes in the surrounding part of the brain
lateral ventricles flow the enlarging cerebral hemispheres
the third ventricle remains a single midline space
in the development of the ventricles we have the cerebral aqueduct, how is this formed and why is it important?
Proliferation of the neural elements of the mesencephalon; This creates a constricted region in the ventricular system → flow of CSF may be easily blocked
how does the occlusion of the cerebral aqueduct occur?
Can be a result of gliosis due to infection or developmental defect of the forebrain, rupture of the amniotic sac, or forking of aqueduct
Tumors in the midbrain
what is the pathophysiology in the occlusion of the cerebral aqueduct?
● Results on lack of communication between the 3rd and 4th ventricles and blocks the withdrawal of CSF from the 3rd ventricle
how does the cerebral aqueduct communicate?
Communicates rostrally with the 3rd ventricle and caudally with the 4th ventricle
in the beginning stages of the development of the 4th ventricle, the ventricles and central canal first form a _______?
a closed system
what happens in the 2nd and 3rd months in the development of the 4th ventricle?
three openings form in the roof of the fourth
what does the caudal layer of the roof of the 4th ventricle consist of?
a layer of ependymal cells internally and connective tissue externally
where do small bulges in the caudal roof appear?
at the lateral extremes of the fourth ventricle thinning the membrane and breaking it down → foramen of Magendie (medial) and foramina of Luschka (lateral)
T/F, the development of 4th ventricle have foramen of Luschka (lateral aperture) on either side? T/F, the Foramen of Magendie (median aperture) is located on the midsection ?
T; T