Lecture 2 and 3: Forebrain: Cerebral cortex and Thalamus, internal capsule

Question 1

Name and describe the functions of artery 1

Answer 1

1: Anterior Communicating Artery (joins the left and right anterior cerebral artery).

Question 2

Name and describe the function of artery 2

Answer 2

2: Posterior Communicating Artery (communiates between posterior and anterior circulations).

Question 3

Name and describe the function of artery 3

Answer 3

Basilar Artery

(The basilar artery is part of the posterior cerebral circulation).

Question 4

Name and describe the function of artery 4

Answer 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.

Question 5

Name and describe the function of artery 5

Answer 5

Left Vertebral Artery

The vertebral arteries are major arteries of the neck. Typically, thevertebral arteries originate from the subclavian arteries.

Question 6

Name and describe the function of artery 6

Answer 6

Left Subclavian

Question 7

Name and describe the function of artery 7

Answer 7

Common Carotid (comes off the aortic arch)

Question 8

Name and describe the function of artery 9

Answer 8

Brachiocephalic Trunk

Question 9

Name and describe the function of artery 10

Answer 9

Right subclavian

Question 10

Name and describe the function of artery 11

Answer 10

Right vertebral

Question 11

Name and describe the function of artery 12

Answer 11

Right common carotid

Question 12

Name and describe the function of artery 13

Answer 12

Right internal carotid

Question 13

Name and describe the function of artery 14

Answer 13

Posterior cerebral

Question 14

Name and describe the function of artery 16

Answer 14

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.

Question 15

Name and describe the function of artery 17

Answer 15

Anterior cerebral
(Fromt he medial aspect of the brain and going to the top).

Question 16

What is the clinical significance of the middle cerebral artery?

Answer 16

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.

Question 17

Which area is most prone to aneurysms?

Answer 17

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.

Question 18

Describe the Circle of Willis

Answer 18

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.

Question 19

What vessels are part of the Circle of Willis?

Answer 19

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.

Question 20

(From the inferior view) draw the blood supply to the brain

Answer 20

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

Question 21

Draw the main features of the Lateral view of the brain

Answer 21

1) Central Sulcus
2) Precentral gyrus
3) Superior frontal gyrus
4) Middle frontal gyrus
5) Inferior frontal gyrus
6) Broca’s area

Question 22

What is the function of the thalamus?

Answer 22

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.

Question 23

Describe the Ventral Posterior portion of the thalamus

Answer 23

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)

Question 24

What are the 2 ventral Nuclear Group of the thalamus?

Answer 24

Ventro Anterior

Ventro lateral

Ventro Posterior Lateral

Ventro Posterior Medial

Question 25

Describe the Ventro-Anterior and Ventro-Lateral part of the Ventral Nuclear Group of the Thalamus

Answer 25

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.

Question 26

Name all of the Subdivisions of the Thalamus

Answer 26

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)

Question 27

Describe the Anterior Nuclear Group

Answer 27

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)**

Question 28

Describe the Papez's Circuit

Answer 28

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)

Question 29

Describe the Medial and Lateral Nuclear group

Answer 29

MD, LD & LP: Integration of sensory input from association cortices (frontal/parietal). Pulvinar: Secondary Visual Cortex (integration of visual type information)

Question 30

Describe the Metathalamus

Answer 30

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

Question 31

What does the thalamus sit on?

Answer 31

A sheet. (reticular sheet) It works with the thalamus and helps control how much sensititvity your upper motor neurons work with.

Question 32

Describe the Internal Capsule (and its structure)

Answer 32

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.

Question 33

Where is the Genu?

Answer 33

In the IC (where the nerve fibres that go from/come out of the face is).