1/17 CSF, Vessels, & Higher Cortical Structure And Function Flashcards
What are the ventricles?
There are four interconnected ventricles
• Paired lateral ventricles (telencephalon)
• Interventricular foramen
• 3rd ventricle (diencephalon)
• Cerebral aqueduct (mesencephalon)
• 4th ventricle (metencephalon & myelencephalon)
What are the regions that the lateral ventricles supply?
Inferior horn – Temporal lobe
Posterior horn – Occipital lobe
Body – Parietal lobe
Anterior horn – Frontal lobe
Where do the lateral ventricles connect/where do they go?
Connected to 3rd ventricle through interventricular foramen (of Monro)
What is the third ventricle?
Flat ventricle between the two halves of the diencephalon
Where is the third ventricle?
Superior to the optic chiasm and midbrain
What are the openings to the third ventricle?
Two superior openings – interventricular foramen
One inferior opening – cerebral aqueduct
What are the boundaries of the fourth ventricle?
Anterior: pons and medulla
Posterior: cerebellum
What are the openings to the fourth ventricle?
Single superior opening – cerebral aqueduct
Inferiorly open to the central canal
What is the structure of the fourth ventricle?
Paired lateral apertures
Single median aperture
What are cisterns?
subarachnoid space that widens in several areas
What does the lumbar cistern consist of?
Cauda equina, filum terminale
What does the cisterna magna consist of?
Posterior inferior cerebellar and vertebral arteries, CN IX-XII
What does the prepontine cistern consist of?
Basilar and superior cerebellar arteries, CN VI
What does the interpeduncular cistern consist of?
Posterior cerebral and posterior communicating arteries, CN III
What does the quadrigeminal cistern consist of?
Pineal gland, great cerebral vein
How is CSF created?
The choroid plexus filters the plasma from the blood to create CSF
Where is choroid plexus found?
in most parts of the ventricles
What is the composition of CSF?
primarily composed of water (99%) with a small amount
of chemicals and nutrients including
– Sodium
– Chloride
– Potassium
– Calcium*
– Magnesium
– Small amounts of protein and glucose
What are the functions of CSF?
Physical support for the brain
Excretory functions allow for the removal of water-soluble metabolites
Channel for chemical communication
What are the chemicals that CSF allows to communicate?
Serotonin
Dopamine
Noradrenaline
Vasopressin
Oxytocin
How is CSF produced from choroid capillaries?
Choroid capillaries are permeable; however, they are surrounded by choroid epithelial cells that have very limited permeability.
This layer allows lipid soluble substances through (e.g. O2 and CO2)
Specialized transport selectively allows other substances through.
About 20 cc/hr are allowed through this barrier.
What is the order of flow/pathway of CSF?
Lateral ventricles
Interventricular foramen
Third ventricle
Cerebral aqueduct
Fourth ventricle
Median & lateral apertures
Subarachnoid space around spinal cord and brain
Absorbed by arachnoid granulations
What are the spaces in which CSF is produced by choroid plexus?
Lateral ventricles
Third ventricle
Fourth ventricle
How is CSF reabsorbed?
CSF passes through the arachnoid granulations (arachnoid villi)
Recent research has also shown that absorption happens through cervical lymphatics by way of the arachnoid surrounding the cranial nerves
Reabsorption usually matches production rate (20cc/hr)
What is hydrocephalus?
When there is more production than reabsorption it causes an increase in pressure
What are the causes of hydrocephalus?
There are over 100 causes
– Communicating
– Non-communicating
What are the symptoms of hydrocephalus?
headaches, nausea, motor or sensory disturbances
How is hydrocephalus traditionally treated?
With a ventroperitoneal shunt
What is non-communicating hydrocephalus?
Indicates a blockage within the ventricular pathway
What is communicating hydrocephalus?
(Non-obstructive) occurs outside of the ventricular system
What provides the blood supply to the anterior circulation to the brain?
Internal carotid artery
What provides the blood supply to the posterior circulation to the brain?
Vertebral arteries
What does the anterior cerebral artery supply?
Medial frontal lobe
Medial parietal lobe
What does the posterior cerebral artery supply?
Inferior & medial temporal lobe
Inferior & medial occipital lobe
Posterior thalamus
Cerebral peduncles
What does the middle cerebral artery supply?
(Travels between frontal and temporal lobe)
Lateral frontal lobe
Lateral parietal lobe
Lateral temporal lobe
Lateral occipital lobe
Insula
What does the lenticulostriate arteries supply?
Basal ganglia
Internal capsule
Amygdala
Anterior thalamus
How does the basilar artery arise and end?
formed by bilateral vertebral arteries
It bifurcates into the posterior cerebral arteries
What are the branches of the basilar artery?
Short and paramedian pontine branches
Long circumferential branches
What do the short and paramedian pontine branches of the basilar artery supply?
Crus cerebri
Central pons
What do the long circumferential branches of the basilar artery supply?
Dorsolateral pons
Superior cerebellar peduncle
What does the superior cerebellar artery supply?
Cerebellum
Superior dorsolateral pons
Dorsal midbrain
What does the anterior inferior cerebellar artery supply?
Cerebellum
Inferior dorsolateral pons
What does the posterior inferior cerebellar artery supply?
Cerebellum
Superior dorsolateral medulla
Where does the anterior spinal artery come from?
Vertebral arteries
What does the anterior spinal artery supply?
Anterior 2/3 of spinal cord
Where do the posterior spinal arteries come from?
Posterior inferior cerebellar arteries
What do the posterior spinal arteries supply?
Posterior 1/3 of spinal cord
What are pyramidal cells
Multipolar neurons (up to 600 dendritic spines)
Main output neurons of the cerebral cortex
What is the size of pyramidal cells?
Size of cell related to distance to target
Where are pyramidal cells found
cortical layers 2, 3, 5, & 6
What are the classifications of pyramidal cells?
Commissural
Association
Projection
Where are commissural pyramidal cells?
Form the corpus callosum
Where are association pyramidal cells?
To the ipsilateral cortex
Where are the projection pyramidal cells?
To other parts of the CNS
What are stellate cells?
Multiple processes in all directions
Project to local targets in the cerebral cortex
Modulates cortical activity
Where are stellate cells found?
In layers 2-6
What are the classifications of stellate cells?
Spiny
Aspiny
What do spiny stellate cells do?
release glutamate which is excitatory
What do aspiny stellate cells do?
release gamma- aminobutyric acid (GABA) which is inhibitory
What makes up the cortex layers?
Neocortex
Allocortex
What makes up the neocortex?
95% of the cortex. It has six distinct layers
I-VI
What makes up the allocortex
Less developed with only 3-4 layers
• Archicortex
• Paleocortex
What makes up the archicortex?
Hippocampus/dentate gyrus
What makes up the paleocortex?
Olfactory bulb/ pirifom cortex
What is cortical layer I called and made of?
Molecular
cell processes
What is cortical layer II called and made of?
External granular
dense stellate cells + small pyramidal cells
What is cortical layer III called and made of?
External pyramidal
loose stellate cells + medium pyramidal cells
What is cortical layer IV called and made of?
Internal granular
dense stellate cells
What is cortical layer V called and made of?
Internal pyramidal
large pyramidal cells
What is cortical layer VI called and made of?
Multiform
various sized pyramidal cells and loose stellate cells
Where does the cells from cortical layer II travel?
To ipsilateral cortical areas
Where does the cells from cortical layer III travel?
To contralateral cortical areas
Where does the cells from cortical layer IV travel?
Input
Where does the cells from cortical layer V travel?
To the striatum, brain stem, & spinal cord
Where does the cells from cortical layer VI travel?
To the thalamus (output)
What are the types of cortical communications?
Projection bundles
Commissural bundles
Association bundles
What do projection bundles connect?
cortex and subcortical structures (i.e. thalamus, spinal cord)
What do commissural bundles connect?
Contralateral cortical areas (layer 3)
What do association bundles connect?
Ipsilateral cortical areas
What are the different types of association fibers?
Superior longitudinal fasciculus
Inferior longitudinal fasciculus
Frontooccipital fasciculus
Cingulum
Uncinate fasciculus
Arcuate fasciculus
Short fibers
What are brodmann’s areas?
52 distinct areas based on histological differences in the cortex as seen in 1905
Do broadmann’s areas follow sulci and gyro?
No
Don’t respect boundaries of sulci and gyri
What do broadmann’s area 1, 2, and 3 make up?
Primary somatosensory cortex
(Around postcentral gyrus)
What does broadmann’s area 5 make up?
Somatosensory association area
What does broadmann’s area 4 make up?
Primary motor cortex
(Around precentral gyrus)
What does broadmann’s area 6 make up?
Premotor cortex
(Around precentral gyrus into some of the superior/middle/inferior frontal gyrus)
What does broadmann’s area 17 make up?
Primary visual cortex
(Around calcarine sulcus)
What does broadmann’s area 18 and 19 make up?
Visual association cortex
What does broadmann’s area 41 make up?
Primary auditory cortex
(Around transverse temporal gyri)
What are the language centers of the brain? Where are these found?
Broca’s area
Wernicke’s area
Arcuate fasiculus
Primarily in the left hemisphere
Where is Broca’s area?
(Brodmann 44, 45)
inferior frontal gyrus (close to primary motor cortex)
Where is Wernicke’s area?
(Brodmann 22, 40)
superior temporal gyrus and supramarginal gyrus (close to primary auditory cortex)
What is prosody?
The ability to translate/produce pitch, volume, tempo and rhythm is contained in the non- dominant hemisphere
(Intonation, would be monotone without)
Where is prosody found in the brain?
Broca’s and Wernicke’s on the right
Where are the reading centers of the brain?
Supramarginal gyrus (40)
Angular gyrus (39)
Word recognition in occipitotemporal gyrus (37)
Word vocalization in Broca’s area (44)
Writing in premotor cortex (6)
Where does a normal brain activate for reading?
Along the right hemisphere of the brain and mid-left hemisphere
Where does a dyslexic brain activate for reading?
Along both hemispheres
Different methods (tactile, auditory) are needed to help dyslexic readers.
