Section 2 Part 1: General Features, Anatomy of the Ventricles, CSF and BBB Flashcards
What does the forebrain do?
Receive information from our sensors and send controlling signals out to motor and visceral systems
What are the complex computations of the forebrain called?
Higher cognitive processes
Within the forebrain, what is the principle structure involved in the higher cognitive processes?
The cerebral cortex is the principle area, but subcortical structure also play a role
What do cognitive deficits signal?
Forebrain lesion, usually a cortical pathology
What are the three subcortical nuclei that are part of the basal ganglia?
1- Caudate
2- Putamen
3- Globus Pallidus
**Together are known as Basal Ganglia with Substantia nigra and subthalamic nucleus
What two subcortical nuclei compose the stratum?
Caudate and Putamen
What are the subcortical nuclei involved in?
Motor control
What do diseases of the basal ganglia result in?
a variety of motor symptoms, including difficulty initiating movement, abnormalities of muscle tone or the development of various involuntary motor movements
What is akinesia?
Difficulty initiating movements
What is rigidity?
Abnormalities in muscle tone
Does the basal ganglia have a role in cognitive functions?
Yes
What is the amydgala?
a subcortical nucleus
What is the role of the amygdala?
It is onvolved in conrolling emotional behavior and is an important component of the limbic system
What does the limbic system include?
1- amygdala
2- anterior portion of the cingulate gyrus
3- orbital and medial prefrontal gyri of the cerebral cortex
4- ventral parts of teh basal ganglia
5- hippocampus
6- parts of the thalamus that project into these cortical regions
What does the limbic system interact?
Portions of the limbic system interact with the hypothalamus and autonomic area of the brainstem
Where do the lateral ventricles reside?
They are large “C” shaped structures that reside in each hemisphere
What does each lateral ventricle consist of?
Anterior horn, body, posterior horn, inferior horn
Where does the anterior horn of the lateral ventricle lie?
Frontal lobe
Where does teh body of teh lateral ventricle lie?
Extends across the frontal and parietal lobe
Where does the posterior horn lie?
occipital lobe
Where does the inferior lobe lie?
Temporal lobe
Where is the third ventricle located?
The third ventricle is located at the midline (near the thalamus)
What punctures the third ventricle?
Thalamic adhesion/ massa intermedia
Do the lateral ventricles communicate with one another, if so, how?
No they do not
Do the lateral ventricles interact with the third ventricle?
Yes they do, via the intraventricular foramen
What is another name for the intraventricular foramen?
Foramen of Monro
Where is the fourth ventricle located?
It is located below the cerebellum (the cerebellum forms the roof) and the pons region forms the floor the ventricle
Does the third ventricle interact with the fourth ventricle, if so, how?
Yes it does, via the cerebal aqueduct
Where doe the cerebral aqueduct lie?
The midbrain (under the superior and inferior colliculi
What ventricle is the foramen of magendie an extension of?
The fourth ventricle, it extends caudally
What ventricle is the foramen of luschka an extension of?
The fourth ventricle, they extend anteriorly
What produces a hollow on the ventral medial surface of the interior horn?
The hippocampus
What does the medial surface of the posterior horn normally abut?
The calcarine sulcus
What is the tectum?
The superior and inferior colliculi. It is dorsal to the aqueduct
What is below the tectum?
The tegument
What is the main function of the Blood Brain Barrier (BBB)?
Maintains a stable environment for neurons to function effectively, protecting the CNS from severe fluctuations in ionic concentrations and circulating hormones and neurotransmitters released from other parts of the body
Does the BBB allow for the entry of many ionic compounds to the CNS?
No, it tends to be exclusionary to many ionic compounds
Where is the actual location of the BBB?
The capillary endothelium
What are the specializations of the BBB/ capillary endothelium?
1- Tight junctions between capillary endothelial cells
2- few endocytotic vesicles for intracellular transport
3- a high number of mitochondria (indicative of high levels of oxidative metabolism)
What can enter the brain through the BBB and how do they cross?
1- lipid soluable substances (O2 and CO2 gases)
2- Facultative and energy- dependent transport of specific water soluble substances ( glucose and amino acids)
3- ion channels allow particular ions to cross
How do substances leave the brain through the BBB?
There is a reveres pump (intracellular transporters) within the astroglia that move lipophilic molecules of the brain into the blood
Can whole cells migrate across a healthy BBB?
Yes– especially lymphocytes and macrophages– but they enter by opening tight junctions
Do all regions of the brain have a BBB?
No, several regions do not have a BBB
Why do some regions of the CNS not have a BBB?
Regions that need to sense fluctuation in the blood, because they are part of the circuitry for regulating these fluxes
What pathologies are usually associated with a breakdown of the BBB?
Brain tumors, bacerial invasions, ischemia
What is the most common cause of BBB breakdown?
Ischemia
Describe the pathology of a stroke:
Loss of tissue oxygenation, introduction of toxins to the brain, ionic fluxes, damaged Na/ K pumps— the latter two cause the cells to fill with water
Eventually edema results and there can be an increase in intracranial pressure that can lead to coma and death.
