Ventricular System Flashcards
Where is CSF produced?
In the choroid plexuses
What is the function of CSF?
-functions as a buffer to absorb stress transferred through the rigid skull
What is the general pathway of CSF?
- ventricles to the surface of the brain
- drain into the venous sinuses of the skull
- flows unidirectionally into subarachnoid space
Pathology due to disruption of CSF circulation causes what?
Hydrocephalus
Where are the lateral ventricles located?
In each hemisphere
Where is the third ventricle?
lies in a midline slit in the dienceohalon
Where is the fourth ventricle located?
Between the pons and the medulla and the cerebellum
What serves for the communication between the lateral ventricles and the third ventricle?
Interventricular foramina
What are the five parts of the lateral ventricles?
- Anterior horn in the frontal lobe
- Body in the frontal and parietal lobes
- Posterior horn projecting back into the occipital lobe
- Inferior horn curving down toward the temporal lobe
- Atrium-where the body and the posterior and inferior horns meet
what makes of the lateral wall of the third ventricle?
-the medial surface of the thalamus and the hypothalamus
the third ventricle has a thin membranous roof containing what?
choroid plexus
anteriorly, the third ventricle ends at what?
-the lamina terminalis
posteriorly, the third ventricle ends how?
-it narrows to become the cerebral aqueduct (aqueduct of sylvius)
where does the interventricular foramen lie?
in the anterior part of each wall of the third ventricle
the portion of the fourth ventricle rostral to its peak is called what?
-medullary velum
the portion of the fourth ventricle caudal to its peak is called what?
inferior medullary velum
what is the floor of the fourth ventricle also called?
the rhomboid fossa
what are the three aperatures that allow CSF to exit the ventricular system to enter the subarachnoid space?
- two lateral aperatures: foramen of luschka
- one median aperature: foramen magendie
the third ventricle communicates with the fourth ventricle by what?
the aqueduct of sylvius
CSF is propelled forward passively by what?
-the pulsations of the brain circulation
how much CSF is within and around the brain? how much is in the ventricles?
- 150-200mL in the brain
- 25 mL in ventricles
what is a choroid plexus?
-strands of highly convoluted and vascular membranous material
where is the choroid plexus enlarged? what is it called?
- in the region of the atrium
- then called the glomus
why can the glomus be seen in X rays?
it becomes calcified with age
how is the choroid plexus formed?
-evagination of the ependymal layer of cells containing arterioles, capillaries, and venules
what kind of cells are in choroid epithelium?
-cuboidal, secretory epithelium
how does the choroid plexus generate CSF?
- by filtering blood
- plasma and fluid can go through fenestrations in the capillaries, but cells cannot
- there are no cells in CSF
does CSF in the subarachnoid space penetrate through the pia mater?
NOOOOOOOOO
what are arachnoid granulations?
small protrusions of the arachnoid through the pia mater into the venous sinuses
-allows CSF to exit subarachnoid space and enter the blood stream
where do the largest granulations lie?
along the superior sagittal sinus
smaller granulations are called what?
villi
arachnoid granulations act as what?
one-way valves
is the rate of production of CSF independent or dependent of blood pressure and intre-ventricular pressue?
relatively independent
what causes hydrocephalus?
-CSF pressure rises and ventricles expand
- excess production of CSF
- blockage of CSF circulation
- deficiency in CSF reabsorption
- vacuum
what is THE MOST COMMON cause of hydrocephalus?
blockage of CSF circulation
what is communicating hydrocephalus?
-ventricles can still communicate, so blockage is outside
what is non-communicating hydrocephalus?
-blockage is within the ventricles
what could cause a defect in reabsorption of CSF?
- congenital absence of arachnoid villi
- obstruction of superior sagittal sinus
what is the triad of symptoms for increased intrcranial pressure?
- headache
- nausea/vomiting
- papilledema
who normally experiences normal pressure hydrocephalus?
elderly!
when is papilledema not seen as a symptom with increased intracranial pressure?
normal pressure hydrocephalus-can be intermittent
what causes normal pressure hydrocephalus?
- decreased reabsorption of CSF at the arachnoid granulations
- blockage is outside ventricles, so it is intermittent and not a constant condition.
who is most likely to experience pseudotumor cerebri?
-obese women
what are symptoms of pseuotumor cerebri?
- headache and visual disturbances
- can be confused with psych issues
- PAPILLEDEMA
- increased ICP
- CONSTANT CONDITION
