Lecture 2 and 3: Forebrain: Cerebral cortex and Thalamus, internal capsule Flashcards
Name and describe the functions of artery 1
1: Anterior Communicating Artery (joins the left and right anterior cerebral artery).
Name and describe the function of artery 2
2: Posterior Communicating Artery (communiates between posterior and anterior circulations).
Name and describe the function of artery 3
Basilar Artery
(The basilar artery is part of the posterior cerebral circulation).
Name and describe the function of artery 4
Left Internal Carotid
The internal carotid then divides to form the anterior cerebral artery and middle cerebral artery. The internal carotid artery can receive blood flow via an important collateral pathway supplying the brain, the cerebral arterialcircle, which is more commonly known as the Circle of Willis.
Name and describe the function of artery 5
Left Vertebral Artery
The vertebral arteries are major arteries of the neck. Typically, thevertebral arteries originate from the subclavian arteries.
Name and describe the function of artery 6
Left Subclavian
Name and describe the function of artery 7
Common Carotid (comes off the aortic arch)
Name and describe the function of artery 9
Brachiocephalic Trunk
Name and describe the function of artery 10
Right subclavian
Name and describe the function of artery 11
Right vertebral
Name and describe the function of artery 12
Right common carotid
Name and describe the function of artery 13
Right internal carotid
Name and describe the function of artery 14
Posterior cerebral
Name and describe the function of artery 16
Middle cerebral (Clinically significant because this is the site that is most easily blocked and also contain the most atherosclerosis).
This artery supplies most of the lateral aspect of the brain- which is why strokes often cause aphasia.
Name and describe the function of artery 17
Anterior cerebral
(Fromt he medial aspect of the brain and going to the top).
What is the clinical significance of the middle cerebral artery?
Most prone to atherosclerosis and blockage which casues strokes.
This artery supplies most of the lateral aspect of the brain- which is why strokes often cause aphasia.
Which area is most prone to aneurysms?
From this circle, other arteries — the anterior cerebral artery(ACA), the middle cerebral artery (MCA), and the posteriorcerebral artery (PCA) — arise and travel to all parts of thebrain.
Brain aneurysms tend to occur at the junctions between the arteries that make up the Circle of Willis.
Describe the Circle of Willis
Circle of Willis is a is a circulatory anastomosis that supplies blood to the brain and surrounding structures
Contains:
1) Anterior cerebral artery (left and right)
2) Anterior communicating artery
3) Internal carotid artery (left and right)
4) Posterior cerebral artery (left and right)
5) Posterior communicating artery (left and right)
The middle cerebral arteries, supplying the brain, are not considered part of the circle.
The arrangement of the brain’s arteries into the circle of Willis creates redundancy for collateral circulation in the cerebral circulation.
If one part of the circle becomes blocked or narrowed (stenosed) or one of the arteries supplying the circle is blocked or narrowed, blood flow from the other blood vessels can often preserve the cerebral perfusion well enough to avoid the symptoms of ischemia.
What vessels are part of the Circle of Willis?
Contains:
1) Anterior cerebral artery (left and right)
2) Anterior communicating artery
3) Internal carotid artery (left and right)
4) Posterior cerebral artery (left and right)
5) Posterior communicating artery (left and right)
The middle cerebral arteries, supplying the brain, are not considered part of the circle.
(From the inferior view) draw the blood supply to the brain
1) Anterior Cerebral artery
2) Anterior Communicating artery
3) Internal carotid artery
4) Middle cerebral artery
5) Posterior communicating artery
6) Posterior cerebral artery (supply neo___ of occipital lobe)
7) Superor cerebrellar artery
8) Pontine arteries (anterior artery supplying pons)
9) Basilar artery
10) Inferior cerebrellar artery (branch of brainstem to the cerebellum)
11) Vertebral artery
12) Anterior spinal artery
Draw the main features of the Lateral view of the brain
1) Central Sulcus
2) Precentral gyrus
3) Superior frontal gyrus
4) Middle frontal gyrus
5) Inferior frontal gyrus
6) Broca’s area
What is the function of the thalamus?
The main function of the thalamus is to relay motor and sensory signals to the cerebral cortex (how much info goes in and out of the cortex).
The thalamus is also involved in the regulation of consciousness, sleep, and alertness.
Describe the Ventral Posterior portion of the thalamus
2 parts- VPLateral and VPMedial
Responsible for incoming info from the spinal cord/periphery (e.g. something has touched you, pain etc.).
Once the fibres has been processed by the thalamus, fibres go to the Primary Sensory Cortex.
There is a homuncular representation in the VPL and VPM (head end is in the VPM and the food region is in the VPL)
What are the 2 ventral Nuclear Group of the thalamus?
Ventro Anterior
Ventro lateral
Ventro Posterior Lateral
Ventro Posterior Medial
Describe the Ventro-Anterior and Ventro-Lateral part of the Ventral Nuclear Group of the Thalamus
Deals with motor planning info from the planning part of the cortex then the basal ganglia. From the VA, fibres go back into the planning part of the cortex to activate muscle via other neurons.
Name all of the Subdivisions of the Thalamus
1) Ventral Nuclear group (VA, VL, VPL, VPM)
2) Anterior Nuclear group
3) Medial Nuclear group
4) Intralaminar nuclear group
5) Lateral nuclear group
6) Metathalamus (MGB, LGB)
Describe the Anterior Nuclear Group
Allow us to take info from the hippocampus, to the fornix mamillary body, to the cingulate gyrus, to the frontal cortex and back again.
is a neural circuit for MEMORY and control of emotional expression
Part of the Papez’s circuit
The hippocampus talks via the Fornix which connects to the mamillary bodies.
Mamillary bodies talk to the Anterior nucleus of the thalamus
The anterior nucleus of the thalamus talks to the cingulate gyrus
The cingulate gyrus talks to the Frontal cortex
This circuit is important because we want to remember things and it allows us to modify behaviour. (e.g. toaster burning smell)
Describe the Papez’s Circuit
The hippocampus talks via the Fornix which connects to the mamillary bodies.
Mamillary bodies talk to the Anterior nucleus of the thalamus
The anterior nucleus of the thalamus talks to the cingulate gyrus
The cingulate gyrus talks to the Frontal cortex
is a neural circuit for MEMORY and the control of emotional expression
This circuit is important because we want to remember things and it allows us to modify behaviour. (e.g. toaster burning smell)
Describe the Medial and Lateral Nuclear group
MD, LD & LP: Integration of sensory input from association cortices (frontal/parietal).
Pulvinar: Secondary Visual Cortex (integration of visual type information)
Describe the Metathalamus
Made up of Lateral and medial Geniculate Body
LGB is involved in visual information. When primary info comes in from the eyes, it goes to the LGB on its way to the visual cortex.
MGB is involved in auditory information. Info comes in from the auditory nerve and goes towards the primary auditory cortex.
You can control what info goes to the PAC and the VC
What does the thalamus sit on?
A sheet.
(reticular sheet)
It works with the thalamus and helps control how much sensititvity your upper motor neurons work with.
Describe the Internal Capsule (and its structure)
Innermost white matter that connects the subcortical structures to the cortical structures.
Structure:
The outer part of the Internal capsule has to do with motor info (Primary motor cortex via IC to the spinal cord). These take a lateral path.
There’s an area through the central area which is called the Genu. The motor information for the face is located in the genu. This means that the face info goes out into the IC in the region of the genu, and the nerves to the rest of the body is posterior/rest of the IC.
The front part- take info for the frontal region of the brain, going from the thalamus for instance.
Medial aspect of the IC is carrying info from the spinal cord (sensory), into the thalamus (VPosterior) and then send fibres out into the IC to be destined for the primary sensory cortex. All of the facial sensory region sits on the genu, the body info (like the motor info) go posterior to this.
There is extension of white matter posterior to this.
Where is the Genu?
In the IC (where the nerve fibres that go from/come out of the face is).
