Functional Anatomy of Cerebral Cortex Flashcards

1
Q

What are the borders of the frontal lobe?

A

anterior to the central sulcus

above the lateral sulcus

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2
Q

What proportion of the cortical surface is occupied by the frontal lobe?

A

40% of the cortical surface area

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3
Q

What are the main subdivisions of the frontal lobe?

A
  • lateral
  • medial
  • orbital
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4
Q

What is the lateral aspect of the frontal lobe?

A

aka convex aspect

contains the:
- pre-central gyrus (primary motor area)

  • superior frontal gyrus
  • medial frontal gyrus
  • inferior frontal gyrus

Latter 3 are separated by the superior and inferior frontal sulci

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5
Q

Where is the primary motor area located?

A

in the pre-central gyrus

located anterior to the central sulcus

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6
Q

Where is the superior frontal gyrus located?

A

continues onto the medial surface of the hemisphere

separated from the underlying cingulate gyrus (limbic lobe) by the cingulate sulcus

motor strip of lower limbs (below T6) is also found here

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7
Q

Where is the inferior temporal gyrus located?

A

aka orbital or orbitofrontal

overlies the orbital cavities

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8
Q

What sections are the orbital regions divided into?

A

divided into 2 areas by the olfactory sulcus/tract

olfactory sulcus contains the olfactory bulb and tract

Medial to the olfactory tract is the straight gyrus/gyrus rectus

remaining orbital region is lateral to the olfactory pathways and is known as the lateral orbital cortex
It contains a poorly define H-shaped orbital sulcus

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9
Q

How can you identify the primary motor cortex?

e.g. on a scan

A

LOOKING @ SUPERIOR BRAIN SURFACE
look for inverted capital omega shape

this corresponds to the part of the motor cortex that controls the contralateral hand

“motor hand area”

Central sulcus will be just posterior to this

AXIAL (HORIZONTAL) MRI/CT
motor hand area omega-shape will be pointing backwards (towards occipital region)
central sulcus will be immediately behind it

=> often easier to see on LHS for right handed individuals

MID-SAGGITAL SECTION
follow cingulate sulcus posteriorly

most posteriorly it will deflect upwards to the superior margin of the cerebral hemisphere
[-> PARS MARGINALIS]
central sulcus is immediately anterior to this

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10
Q

Where is the inferior frontal gyrus located?

A

below the inferior frontal sulcus

on the convexity of the frontal lobe

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11
Q

How is the inferior frontal gyrus divided?

A

divided by 2 branches of the lateral sulcus (Sylvian fissure).

These branches are known as the anterior horizontal or anterior ascending rami

3 portions

gives the overall inferior frontal gyrus an M-shape

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12
Q

What is the part of the inferior frontal gyrus that is closest to the orbit called?

A

PARS ORBITALIS

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13
Q

What is the portion of the inferior frontal gyrus between the ascending and horizontal rami called?

A

PARS TRIANGULARIS

this is because it is triangular in shape

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14
Q

What is the portion of the inferior frontal gyrus behind the ascending rams called?

A

PARS OPERCULARIS

belongs to the opercular region

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15
Q

What is the OPERCULAR REGION near the inferior frontal gyrus?

A

cortex surrounding the lateral sulcus and overlying insular area

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16
Q

What is the significance of the 3 regions within the inferior frontal gyrus?

A

the TRIANGULAR and OPERCULARIS regions together constitute BROCA’S AREA

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17
Q

Where is the LATERAL PREMOTOR AREA?

A

cortex in front of the motor strip

on the convexity of the cerebral hemisphere

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18
Q

What is the SUPPLEMENTARY MOTOR AREA (SMA)?

A

equivalent to the motor strip on the lateral portion of the frontal lobe

but located on the MEDIAL surface of the frontal lobe

aka MEDIAL PREFRONTAL CORTEX

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19
Q

What is contained within the PREFRONTAL CORTEX?

A

this describes the remaining non-motor part of the frontal lobe

including entire orbital region

makes up 30% of the total cortical surface area

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20
Q

What is the function of the PREFRONTAL CORTEX?

A
  • cognition
  • goal-directed behaviour
  • social interactions
  • intelligence
  • creativity
  • Broca’s area is here too (expressive language)
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21
Q

What are the two main regions of the prefrontal cortex?

A

DORSOLATERAL PREFRONTAL CORTEX
on the convexity of the frontal lobe

ORBITOMEDIAL PREFRONTAL CORTEX
includes both the orbital and medial surfaces

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22
Q

What is the function of the DORSOLATERAL PREFRONTAL CORTEX?

A

cognitive functions, especially “executive functions”
e.g. organising and planning

contributes to basal ganglia loops that pass through the CAUDATE NUCLEUS
[C = cognition]

regulation of normal thinking

found to be abnormally active in OCD patients

also contains frontal eye fields - controlling attention and gaze and voluntary eye movements

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23
Q

What is the function of the ORBITOMEDIAL PREFRONTAL CORTEX?

A

regulation of behaviour, personality and social conduct

patients with lessons in this region can become rude, disinhibited and inappropriate

decision-making and judgement are severely impaired

this can lead to rash and imprudent behaviour that may go alongside unconcern or lack of insight

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24
Q

What eye signs may a patient with frontal lobe damage experience?

A
  • attention problems

- impaired eye movement

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25
Q

Where is the PARIETAL LOBE located?

A

posterior to the central sulcus and superior to the lateral sulcus

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26
Q

What is the boundary between the parietal and occipital lobes?

A

parieto-occipital sulcus

can only be seen from the medial aspect of the hemisphere

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27
Q

What is contained within the LATERAL PARIETAL REGION?

A

post-central gyrus or primary SS area

immediately posterior to the motor strip

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28
Q

How is the parietal lobe divided?

A

divided by the intra-parietal sulcus

forming the INFERIOR and SUPERIOR PARIETAL LOBULES

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29
Q

What is the INTRA-PARIETAL SULCUS?

A

a deep cleft orientated at right angles to the central sulcus

30
Q

What are the borders of the SUPERIOR PARIETAL LOBULE?

A

continues onto the medial surface of the hemisphere => PRECUNEUS (rectangular shaped)

31
Q

What are the borders of the PRECUNEUS?

A

paracentral lobule (in front/anterior)

occipital lobe (behind/posterior)

posterior cingulate cortex (below/inferior)

32
Q

What is the function of the post-central gyrus/sensory strip?

A

somatic sensation

termination point for the ascending somatic sensory pathways
e.g. dorsal column and spinothalamic

33
Q

What is the POSTERIOR PARIETAL CORTEX?

A

located behind the somatosensory strip

known as the SOMATOSENSORY ASSOCIATION CORTEX

involved in visuospatial representation of objects in extra-personal space

34
Q

Where does the SOMATOSENSORY ASSOCIATION CORTEX receive projections from?

A

aka posterior parietal cortex

‘WHERE’ PATHWAY
input from the occipital cortex (info on the location and movement of objects)

this is important for object interaction

35
Q

Which areas are important fo ordinary daily activities?

e.g. crossing the road, using cutlery

A
  • posterior parietal region
  • frontal lobe

[therefore, parietal damage may cause disruption to these activities]

36
Q

How is the posterior parietal region involved in VISUAL ATTENTION and VISUAL GAZE?

A

the region identifies interesting objects in the environment

via projections to the frontal eye fields

37
Q

How may strokes in the posterior parietal regions or other lesions present clinically?

A

attentional problems

e.g. neglect of the opposite half of the world

38
Q

What occurs in the classical parietal neglect syndrome ?

A

usually caused by a right parietal lesion

patient can see normally but fails to pay attention to the left side

in severe forms, patients may not be aware of these deficits and in order to cover them up will subconsciously invent a narrative when challenged
=> ANONSOGNOSIA

39
Q

What are PRAXES?

A

= initiation of semi-automatic motor sequences

"motor programmes" e.g. tying shoelaces or using scissors 
these skills (procedural memory) are stored in the premotor cortex but selected by the posterior parietal lobe
40
Q

What is APRAXIA?

A

patients who have difficulty with semi-automatic motor sequences

usually caused by a lesion in the parietal lobe, frontal lobe on the white matter connections between the two

41
Q

What is the functions of the INFERIOR PARIETAL REGION?

A

in the DOMINANT/VERBAL hemisphere (usually LHS)
implicated in symbol representation, concepts of number, maths and physics ability
and reading and writing

42
Q

What is GERSTMANN SYNDROME?

A

inferior parietal lobe lesions
especially on the LHS

Sx with simple arithmetic, left-right confusion and difficulty naming fingers

43
Q

Where are the borders of the medial part of the parietal lobe?

A

lies between the paracentral lobule (anteriorly) and the cuneaus of the occipital lobe (posteriorly)

44
Q

What is the medial part of the parietal lobe called?

A

PRECUNEAUS

45
Q

When does the PRECUNEUS show increased perfusion (e.g. by fMRI or PET scan)?

A
  • daydreaming
  • quiet contemplation
  • mediation
  • recall of episodic memories
  • visualisation of both real and imaginary objects in the “mind’s eye”
46
Q

Where is the occipital lobe?

A

Posterior to the parieto-occipital sulcus and pre-occiptial notch

47
Q

What are sub-sections of the occipital lobe?

A

Surfaces:

  • medial
  • lateral
  • inferior

concerned entirely with vision

48
Q

What divides the medial occipital lobe? What is it divided into?

A

divided by the undulating Calcarine sulcus

into the wedge shaped CUNEUS (superiorly)

and the tongue-shaped GYRUS (inferiorly)

49
Q

Where is the primary visual cortex?

A

in the crease of the CALCARINE SULCUS

most of the exposed surface of the occipital surface is the visual association cortex

50
Q

What is the “WHAT PATHWAY”?

A

visual info relating to

  • form
  • colour

passes inferior from occipital lobe -> temporal lobe

via the temporal lobe visual stream (aka ‘what pathway’)

info is integrated by the lateral + inferior temporal cortex

  • identify objects
  • categorise objects
    (e. g. living vs non-living)
51
Q

What is AGNOSIA?

A

failure to recognise objects

52
Q

Where is the TEMPORAL LOBE?

A

sits below the lateral sulcus

projects downwards and forward

posterior boundary: pre-occipital notch

53
Q

What are the areas of LATERAL TEMPORAL REGION?

A

[similar to the frontal lobe]

GYRI:

  • superior
  • middle
  • inferior

divided by superior and inferior sulci

54
Q

What is the nature of the SUPERIOR SURFACE of the TEMPORAL LOBE?

A

flat like a table top

it is hidden within the lateral sulcus. If this was prised open, then you could see the superior surface.
The more transverse temporal gyri can be identified orientated posteriorly and medially

55
Q

What is found within the most ANTERIOR TRANSVERSE TEMPORAL GYRUS?

A

primary auditory cortex

receives the central auditory pathways

surrounding cortical territory = auditory association cortex

56
Q

What is the AUDITORY ASSOCIATION CORTEX responsible for?

A

is specialist for the recognition of speech sounds

in the language dominant hemisphere

57
Q

What is the function of the LATERAL TEMPORAL REGION?

A

object recognition and categorisation

useful in understanding objects in relation to one another

Role in semantics (understanding of words and concepts) - implicated in semantic dementia

58
Q

What are the main cortical language areas?

A

BROCA’s area
inferior frontal gyrus

WERNICKE’s area
posterior third of the superior temporal gyrus
(part of auditory association cortex)

59
Q

What is BROCA’s area?

A

‘motor’ language area

involves production of speech and language

ensures that grammar and syntax rules obeyed
(allows listening to known who did what to whom)

60
Q

What is WERNICKE’s area?

A

‘sensory’ language area

recognition of speech sounds
understanding of spoken language

61
Q

Where is the area for where WRITTEN LANGUAGE is understood?

A

in the inferior parietal lobe

areas are adjacent to Wernicke’s area (temporal lobe)

62
Q

What connects Broca’s (anterior) and Wernicke’s (posterior) language areas?

A

ARCUATE FASCICULUS

an arc shaped white matter bundle

starts in the frontal lobe, passes posteriorly and sweeps down into the temporal lobe

63
Q

What is DYSPHAGIA?

A

ACQUIRED disorder of spoken and written language

may be caused by cortical or white matter damage or disease

64
Q

What do lesions in Broca’s area cause?

A

“anterior hemispheric lesions”

non-fluent dysphagia
speech is effortful, disjointed slow and hesitant
marked difficultly finding words

patients are aware of their dysphagia, are and often frustrated

comprehension is preserved

65
Q

How can COMPREHENSION be assessed in dysphagia?

A

ask patient to perform a multi-step task

e.g. pick up paper, fold in half and place under table

66
Q

What do lesions in Wernicke’s area cause?

A

“posterior hemispheric lesions”

patients can speak without effort, normal rate and rhythm, flow and quantity

but with abnormal speech content, eg word substitutions, neologisms (non-sense words)

patients are unaware of their speech issues, due to an inability to self-monitor speech

Comprehension is severely impaired
patient finds it difficult to understand and follow instructions

67
Q

What are NEOLOGISMS?

A

nonsense words

68
Q

What is CONDUCTION APHASIA?

A

normal expression and comprehension

but selective problem repeating phrases

e.g. repeat after me “no ifs, ands or buts”

lesion in the arcuate fasciculus, therefore disconnects sensory and motor language areas

69
Q

What is GLOBAL APHAGIA/DYSPHAGIA?

A

often seen in patients who have had a major stroke

both language areas are affected

severe deficit in both language expression and comprehension

70
Q

What is the contribution of the ‘homologous’ areas in the non-dominant hemispheres in normal communication?

A
BROCA's homolog 
non-verbal aspects of expressive communication 
- rate modulation
- rhythm
- speech intonation 
- gesticulations 
- facial expressions 

WERNICKE’s homolog
understanding subtlety of intonation or the music of speech
e.g. tone used in sarcasm