Neuro lecture 6 Flashcards
The prosencephalon is the embryological origin for what two aspects of the brain?
telencephalon and diencephalon
The rhombencephalon is the embryological origin for what three aspects of the brain?
metencephalon, myelencephalon and myelon
The left and right lateral ventricles communicate with the 3rd ventricle through what foramina?
Foramina of Monro (also called the inter ventricular foramina)
How does the 3rd ventricle communicate with the 4th ventricle?
cerebral aqueduct
what are the four distinct parts of the lateral ventricle?
Anterior Frontal Horn, Body (corpus), posterior (occipital horn) and inferior (temporal) horn
the 4th ventricle communicate with the subarachnoid space via what foramina?
the two foramina of Luschka (lateral) and the foramen of Magendie (midline)
Choroid plexus occupies all ventricles of the brain however it is not present in the cerebral aqueduct, why?
because it is so narrow
the choroid plexus is a rich network of blood vessels of the pia mater that form a semi-permeable filter between what two things?
arterial blood and CSF
what is the function of the CSF?
serves to support and cushion the CNS against injury, serves nutritive functions and removes metabolic waste
what is the normal pressure?
65-200mm H20
where is CSF produced?
Choroid Plexus of the lateral, 3rd and 4th ventricles. Additionally by ependyma, glia, pail and arachnoid vessels
describe the route of CSF
circulates from the lateral ventricles into the third ventricle via the foramina of monro, to the cerebral aqueduct, to the 4th ventricle, into the subarachnoid space via the foramina of Luschka (lateral, hence why there is two) and Magendie (medial)
what should CSF be free of?
white blood cells, red blood cells, and glucose
what does it mean if you get blood in the CSF?
Subarachnoid hemorrhage
CSF is high in what contents relative to serum?
Na, Cl, and Mg
what is the total volume in the ventricles and subarachnoid space of CSF?
140mL
Extraventricular CSF returns to the venous system through what?
through small membranous villi, arachnoid granulations, located along the superior sagittal sinus.
what structure located along the superior sagittal sinus ensures the unidirectional movement of fluid into the venous system?
Arachnoid villi
there is no actual subdural or epidural spaces, so what does this mean when someone refers to these spaces?
the space is created as a result of trauma, infection or pathological
Describe what happens if you develop a pineal gland tumor?
The cerebral aqueduct becomes blocked and therefore the CSF backs up and this enlarges the lateral and 3rd ventricles
drainage of blood from the brain is chiefly into what?
venous dural sinuses, which are channels between the two layers of dura of the brain
do venous dural sinuses have valves?
no
the venous dural sinuses receive blood from what three major sources?
cerebral veins (major source), diploic veins and emissary veins
venous sinuses have little tendency to collapse, why?
because of the fibrous consistency of the dura mater.
the emissary veins connect what two veins?
extra cranial with intracranial veins
what sinuses are considered to be the unpaired dural venous sinuses?
Superior longitudinal (sagittal) sinus, Inferior sagittal sinus, straight sinus and small occipital sinus
the superior sagittal sinus is a continuation of what vein?
nasal vein
what veins does the superior sagittal sinus receive blood from?
cerebral, diploic and emissary
what veins does the inferior sagittal sinus receive blood from?
veins on the medial surface of the brain
the straight sinus is a posterior continuation of what vein?
great cerebral vein of Galen this then joints the superior sagittal sinus to form the confluence of sinuses
what are the paired dural venous sinuses?
Transverse Sinus, Cavernous Sinus, Sigmoid Sinus, Superior and Inferior petrosal sinus, and sphenoparietal sinuses
describe the blood drainage into the transverse sinus?
receives blood from the superior sagittal sinus and straight sinus and drains into the internal jugular veins via the sigmoid sinuses
describe the blood drainage into the cavernous sinuses?
receive blood from the superficial middle cerebral veins and superior ophthalmic veins and drain into the internal jugular veins and transverse sinuses
how do the cavernous sinuses communicate?
via intercavernous sinuses as well as with the petrosal sinuses and the pterygoid plexus of veins.
which sinuses are the largest and most clinically important?
cavernous sinuses
where do the sigmoid sinuses review their blood from?
inferior cerebrum, cerebellum and emissary veins. (continuation of the transverse sinuses)
where do the superior and inferior petrosal sinuses drain from?
cavernous sinuses
where do the sphenoparietal sinuses receive their blood from?
superficial middle cerebral veins
what are the veins of the spinal cord?
anterior median spinal vein, anterolateral spinal vein, posterolateral spinal vein, posterior median spinal vein and internal venous plexus
there are organs surrounding the ventricular system called the circumventricular organs, do they have tight blood brain barriers?
no very loose
describe the role of the pineal gland as a circumventricular organ
mediating circadian rhythms- melantonin
describe the role of the area postrema as a circumventricular organ
body fluids (vomiting control center) and homeostasis. the location of this organ is close to CN IX AND X which controls your gag reflex, so it makes sense that it is the vomiting control center
describe the role of the organum vasculosum as a circumventricular organ
balances our fluids and electrolytes. so basically the organum vasculorum is constantly checking our blood to make sure it is in balance before it goes into the ventricular circulation
describe the role of the subfornical organ as circumventricular organ
thirst regulating center
describe the role of the subcommissural organ as a circumventricular organ
secretes various glycol-proteins into the CSF
describe the role of the median eminence of the third ventricle in terms of a circumventricular organ.
controls hypophysiotrophic hormones before they are conveyed to the pituitary gland
what condition would you see that results from insufficient CSF absorption and therefore enlargement of ALL ventricles?
Communicating Hydrocephalus
what condition results from obstruction of inter ventricular foramina, cerebral aqueduct or the foramina of Luschka and Magendie? (not all ventricles are enlarged)
non communicating (obstructive ) hydrocephalus
what condition reflects a complication of infection of the middle ear, sinuses, nasopharynx, scalp or face
thrombosis of the dural sinus.
If a patient presents with nausea, vomiting and a headache what is the first thing you should think of as a cause of the symptoms?
increased intracranial pressure
