Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro > Cortex (from cortex, thalamus & hypothalamus) > Flashcards

Cortex (from cortex, thalamus & hypothalamus) Flashcards

1
Q

Raised fold in the cortex

A

Gyrus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Fissure in the cortex

A

Sulcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Discuss the cerebral microstructure

A
  1. cell bodies of cortical neurones are always arranged in layers, that usually lie parallel to the surface of the brain
  2. the layer of neurons closest to the surface (the most superficial layer) is separated from the pia mater by a zone that lacks neurons → the molecular layer
  3. at least one cell layer contains pyramidal cells that emit large dendrite (apical dendrites) that extend up to layer I where they form multiple branches → pyramidal cells in the prefrontal cortex have up to 23 times more dendritic spines than those in the primary visual area (may allow for more extensive sampling of inputs, as required by higher-order processing of visual information)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What two divisions may the cortex consist of?

A
  1. the neocortex (differentiated into 6 horizontal layers)

2. the allocortex, which contains the hippocampus (which has 3 cortical layers) and olfactory cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many layers does the hippocampus have?

A

3 at most

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Discuss cortical columns

A

Neurons in various layers connect vertically to form small microcircuit → these are cortical columns

also known as hypercolumns

they consist of groups of neurons that have nearly identical receptive fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are Broadmann’s areas distinguished by?

A

Differences in histological structure and functional roles in:
- sensation, cognition and behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What neurons are the most common in the cortex?

A

Pyramidal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What neurotransmitter do pyramidal neurons utilise?

A

Glutamate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Discuss the 3 different fibres types in the cortex

A

Commissural (transverse fibres) → connect the two hemispheres
Association → connect regions in the same hemisphere
Projection → leave the cortex and project to different regions of the CNS - e.g. thalamus & spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How many layers does the cortex have?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Mnemonic for layers of the cortex

A

From the outside to the inside:
Molecular (plexiform), external granular, external pyramidal, internal granular, internal pyramidal, multiform (fusiform) layers (‘Miles Per Gallon Is Gallon Per Miles’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Descibre the molecular layer (layer I)

A
  1. Contains few scattered neurons and consists mainly of extensions of apical dendritictufts of
    pyramidal neurons and horizontally oriented axons, as well asglial cells
  2. Also, some spinystellate cellscan be found here.
  3. Inputs to the apical tufts are thought to be crucial for the ‘‘feedback’’ interactions in the
    cerebral cortex involved in associative learning and attention
  4. While it was once thought that the input to layer I came from the cortex itself, it is now
    realized that layer I across the cerebral cortex mantle receives substantial input from ‘‘matrix’’
    or M-type thalamus cells (in contrast to ‘‘core’’ or C-type that go to layer IV)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the external granular layer (layer II)

A

Contains smallpyramidal neuronsand numerous stellate neurons

Can be long enough to be association fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe external pyramidal layer (layer III)

A

Contains predominantly small and medium-sizepyramidal neurons

  • The apical dendrites of these cells extend superficially and reach the molecular layer
  • the basal processes join the subcortical white matter and then project again to the cortex, so they serve as both association and commissural corticocortical fibers.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the interal granular layer (layer IV)

A
  • Contains different types ofstellateandpyramidal neurons,
  • is the main target of
    thalamocortical afferents from thalamus type C neurons as well as intra-hemispheric
    corticocortical afferents
  • main input to cortical station (most stimuli from the periphery arrive here)
  • therefore contains sensory areas:
  • Stellate cells of the primary sensory cortex receive fibers from the ventral posterolateral (VPL) and ventral posteromedial (VPM) nuclei of the thalamus
  • Primary visual cortex receives fibers from the lateral geniculate nucleus
  • Stellate cells from primary auditory cortex receive projections from the medial geniculate nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the internal pyramidal layer (layer V)

A

Contains LARGEpyramidal neuronswhich give rise to axons leaving the cortex and running
down to subcortical structures (such as thebasal ganglia).

  • In the primary motor cortex of the frontal lobe, layer V containsBetz cells, whose axons travel
    through theinternal capsule, thebrain stemand the spinal cord forming the corticospinal
    tract, which is the main pathway for voluntary motor control.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the multiform layer (layer VI)

A
  • Contains few largepyramidal neuronsand many small spindle-like pyramidal and multiform
    neurons
  • Layer VI sends efferent fibers to the thalamus, establishing a very precise reciprocal
    interconnection between the cortex and the thalamus – layer VI neurons from one cortical column connect with thalamus neurons that provide input to the same cortical column; these
    connections are both excitatory and inhibitory
  • Neurons sendexcitatoryfibers to neurons in the thalamus and also send collaterals to
    thethalamic reticular nucleusthatinhibitthese same thalamus neurons or ones adjacent to
    them – one theory is that because the inhibitory output is reduced by cholinergicinput to the
    cerebral cortex, this provides thebrainstemwith adjustable “gain control for the relay
    oflemniscalinputs
  • Cortical areas that lack a layer IV are called agranular; cortical areas that have only a
    rudimentary layer IV are
    called dysgranular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which layers are the output pyramidal cells located in?

A

3, 5 and 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What do the columns represent?

A

The functional units of the cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the anatomy of the corpus callosum

A
  1. Theposterior(back) portion of the
    corpus callosum is called thesplenium
  2. theanterior(front) is called thegenu(or knee)
  3. between the two is the truncus, or body
  4. The part between the body and the splenium is often markedly narrowed – isthmus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe the area of the brain connecting the prefrontal cortex between the two halves

A

Thinner axons in the genu

These fibres arise from a fork-like bundle of fibres in the tapetum (main body of fibres), called the forceps anterior

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the connection of the motor cortex between the two hemispheres

A
  • Thicker axons in the mid-body or trunk, innerconnect areas of the motor cortex
  • proportionately more of the corpus callosum is dedicated to supplementary motor regions, including Broca’s area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the part of the the allows exchange of somatosensory information between the two hemispheres?

A

The posterior body of the corpus, known as the splenium, communicates somatosensory information between the two halves of the parietal lobe and the visual cortex at the occipital lobe

These are the fibres of the forceps posterior

25
Q

What is the internal capsule?

A

A white matter structure situated in the inferomedial part of each cerebral hemisphere (boomerang shape)

26
Q

What does the internal capsule separate?

A

The caudate nucleus and the thalamus from the putamen and globus pallidus

27
Q

What does the internal capsule consist of?

A

Both ascending and descending axons

28
Q

What forms a large part of the internal capsule? What does this carry?

A

Corticospinal tract

Motor info from the primary motor cortex to the lower motor neurons of the spinal cord

29
Q

What does the anterior limb of the internal capsule contain?

A

a) Frontopontine(corticofugal) fibers project fromfrontal cortextopons
b) Thalamocortical fibers (part of thethalamocortical radiations) connect
themedialandanteriornuclei of the thalamus to thefrontal lobes(these are severed during
aprefrontal lobotomy).

30
Q

What can the internal capsule be divided into?

A

Anterior limb
Genu
Posterior limb

31
Q

What does the genu contain?

A

containscorticobulbar fibers, which run between thecortexand thebrainstem.

32
Q

What does the posterior limb contain?

A

containscorticospinal fibers, sensory fibers (including

themedial lemniscusand theanterolateral system) from the body and a few corticobulbar fibers

33
Q

What is the fornix?

A

The fornix is a C-shaped bundle of nerve fibers in the brain that carries signals from
the hippocampus to the mammillary bodies and then to
the anterior nuclei of thalamus

it is part of the limbic system

34
Q

What connects the fornix to the corpus callosum?

A

Septum pellucidum

35
Q

What are the posterior bifurcations of the fornix called?

A

Columns of the fornix

36
Q

What does the fornix pass through to reach the mamillary body?

A

Hypothalamus

37
Q

Describe the precommisurral fornix

A

composed of the fibers that descend in front of the anterior commissure. They relay onto the septal nuclei (medial olfactory area), the ventral striatum, and the cingulate gyrus.

38
Q

Describe the postcommisurral fornix

A

the postcommissural fornix are the fibers that pass behind the anterior commissure and relay onto the mammillary bodies and the anterior nuclei of the thalamus. A small amount of fornical fibers pass above the splenium of corpus callosum to reach the structures above the corpus callosum. Those fibers constitute the dorsal fornix.

39
Q

Main function of the fornix

A

the primary role of the fornix is to transmit the information from the hippocampus to the mammillary bodies and to the anterior nuclei of thalamus

thought to play a key role in memory

40
Q

Functional anatomy areas of the cortex → draw as well

A 
Somatosensory
- Motor and pre-motor
- Visual
- Auditory
- Posterior parietal
- Orbitofrontal
- Olfactory
- Limbic
Look on OneNote
41
Q

Describe thalamocortical projections

A

Thalamocortical fibers have a bush or tree-like appearance as they extend into theinternal capsuleand
project to the layers of the cortex.
- The main thalamocortical fibers extend from different nuclei of thethalamusand project to the visual
cortex, somatosensory (and associated sensori-motor) cortex, and the auditory cortex in the brain.
- Visual input from the optic tract is processed by thelateral geniculate nucleusof thethalamus
- auditory input processed in themedial geniculate nucleus
- Somatosensory input processed in theventral posterior nucleus
- Thalamocortical radiations also innervate the gustatory pathways, as well as pre-frontal motor areas

42
Q

Describe corticothalamic projections. Which nucleus recieves corticothalamic feedback? From which layer of the cortex do these mainly come?

A

Thalamic nuclei project to cortical areas of distinct architectural organization and relay the processed
information back to the area of original activity in the thalamus viacorticothalamic(CT) fibres
- Thethalamic reticular nucleus(TRN) receives incoming signals via corticothalamic pathways and
regulates activity within the thalamus accordingly
- Cortico-thalamic feedback neurons are mostly found in layer VI of the cortex.

  • Reciprocal CT projections to the thalamus are of a higher order than, and synapse with the TRN in
    much greater number than do thalamocortical projections to cortex – this suggests that the cortex has
    a much bigger role in top down processing and regulation of thalamic activity than do the processes
    originating in thalamic interneurons.
43
Q

What s the arterial cerebral circulation normally divided into?

A

Anterior cerebral circulation and posterior cerebral circulation

44
Q

What are the two main pairs of arteries that supply the cerebral arteries and the cerebrum?

A
  • internal carotid

- vertebral

45
Q

What are the anterior and posterior cerebral circulations interconnected via?

A

Bilateral posterior communicating arteries - part of the circle of Willis - this provides backup circulation

46
Q

Describe the anterior cerebral circulation - what is it supplied by?

A
  1. Internal carotid arteries – these large arteries are
    the left and right branches of thecommon carotid
    arteriesin the neck which enter the skull, as
    opposed to theexternal carotidbranches which
    supply the facial tissues. The internal carotid artery
    branches into theanterior cerebral arteryand
    continues to form themiddle cerebral artery
  2. Anterior cerebral artery(ACA) – left and right anterior
    cerebral arteries connected by anterior communicating
    artery, within and along the floor of the cerebral vault.
  3. Middle cerebral artery(MCA)
47
Q

What arteries form the posterior cerebral circulation?

A
  1. Vertebral arteries: These smaller arteries branch from
    thesubclavian arteries; within thecranium the two vertebral arteries fuse into the basilar artery
    - Posterior inferior cerebellar artery(PICA) is largest branch off of vertebral arteries
  2. Basilar artery: Suppliesmidbrain,cerebellum, and usually branches into posterior cerebral artery
    - Anterior inferior cerebellar artery(AICA)
    - Pontine branches
    - Superior cerebellar artery(SCA)
  3. Posterior cerebral artery(PCA)
  4. Posterior communicating artery
48
Q

What is the structure of the venous drainage of the brain?

A

Drainage by veins which empty into dural venous sinuses

49
Q

Where do the dural venous sinuses lie?

A

Between the periosteal and meningeal layers of the dura mater

50
Q

What do all the dural sinuses ultimately drain into?

A

The internal jugular vein

51
Q

How many venous sinuses are there in total?

A

11

52
Q

Describe the venous sinuses

A

The straight, superior, and inferior sagittal sinuses are found in the falx cerebri of the dura mater. They converge at the confluence of sinuses (overlying the internal occipital protuberance). The straight sinus is a continuation of the great cerebral vein and the inferior sagittal sinus.

From the confluence, the transverse sinus continues bi-laterally and curves into the sigmoid sinus to meet the opening of the internal jugular vein.

The cavernous sinus drains the ophthalmic veins and can be found on either side of the sella turcica. From here, the blood returns to the internal jugular vein via the superior or inferior petrosal sinuses

Draw them! OneNote

53
Q

What may the veins of the brain be divided into?

A

Superficial and deep gorups

54
Q

Discuss the superficial venous system

A
  1. Superior cerebral veins: Drain the superior surface, carrying blood to the superior sagittal sinus.
  2. Superficial middle cerebral vein: Drains the lateral surface of each hemisphere, carrying blood to the cavernous or sphenopalatine sinuses.
  3. Inferior cerebral veins: Drain the inferior aspect of each cerebral hemisphere, depositing blood into cavernous and transverse sinuses.
  4. Superior anastamotic vein (Trolard): Connects the superficial middle cerebral vein to the superior sagittal sinus.
  5. Inferior anastamotic vein (Labbé): Connects the superficial middle cerebral vein to the transverse sinus
55
Q

Discuss the deep venous system

A
  1. Subependymal veins – There are numerous subependymal veins, which will not be described here in detail. These receive blood from the medullary veins and carry it to the dural venous sinuses. The great cerebral vein (vein of Galen) is worthy of a mention; it is formed by the union of two of the deep veins, and drains into the
    straight sinus.
  2. Medullary veins: Originate 1-2cm below the cortical grey matter, and drain into subependymal veins. These drain the deep areas of the brain.
56
Q

Consequences of lesion to visual cortex

A

Scotoma (hole in visual field)

57
Q

Consequences of lesion to motor cortex

A

Lesions of the precentral gyrus (primary motor cortex) result inparalysisof the
contralateral side of the body

58
Q

Consequences of lesion to somatosensory cortex

A

Lesions in S1 impair somatosensation (dysfunction in texture, size and
shape discrimination)

59
Q

Consequences of lesion to posterior parietal cortex

A 
the two most striking consequences of PPC lesions are apraxia and
hemospatial neglect (neglect syndromes and acquired dyslexias)

Left hemisphere lesions cause Broca’s aphasia

Right hemisphere lesions cause hemispatial neglect (failure to perceive and process stimuli
from one side of the body, most commonly contralateral side) – hemispatial neglect occurs
more commonly in right hemisphere, so often left-sided neglect

Neuro (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions