Chapter 10: Cerebral Cortex Flashcards
What layer of the neocortex is the termination of the thalamocortical projections?
internal granular layer
What are the 6 layers of the neocortex?
I. molecular
II. external granular
III. External pyramidal layer
IV. Internal granular layer
V. Internal pyramidal layer
VI. Multiform layer (layer of polymorphic cells)
Which layer of the neocortex give rise to the corticospinal and corticobulbar tracts?
multiform layer
What areas of the brain are supplied by the middle cerebral artery (MCA) supplies? (in general)
- lateral surface of the frontal, parietal, and upper temporal lobes
- posterior limb and genu of the internal capsule
- most of the basal ganglia
Left sided middle cerebral artery occlusion can lead to what condition specific conditions?
Broca or Wernicke aphasia
Right sided middle cerebral artery occlusion?
left sided neglect
Occlusion of branches of the middle cerebral artery that supply Meyer’s loop fibers in the temporal lobe result in what condition?
contralateral superior quadrantanopsia
What structures does the ACA supply?
medial surface of the frontal and parietal lobes; anterior 4/5 of corpus callosum; anterior limb of internal capsule
What areas of the brain does the PCA supply?
supplies occipital lobe; lower temporal lobe; splenium; midbrain
What is the most common site for an aneurysm?
where the anterior communicating artery joins an anterior cerebral artery
How do thrombotic cerebral infarcts appear?
anemic/ pale infarct; usually atherosclerotic complication
How do embolic cerebral infarcts appear?
hemorrhagic/ red infarct; from heart or atheroscelrotic plaques middle cerebral artery most vulnerable to emboli
How do hypotension cerebral infarcts appear?
“watershed” areas and deep cortical layers most affected
How do infarcts caused by hypertension appear?
lacunar infarcts; basal ganglia, internal capsule, and pons most affected
Cause of epidural hematoma
rupture of middle meningeal artery after skull fracture
almost always traumatic
Characteristics of an epidural hematoma?
lucid interval before loss of consciousness (“talk and die” syndrome)
What is the cause of a subdural hematoma?
- usually caused by trauma
- rupture of bridging veins (drain brain to dural venous sinuses)
What is the cause of subarachnoid hemorrhage?
ruptured berry aneurysm most commn cause
Predisposing factors of subarachnoid hemorrhage?
Marfan syndrome, Ehlers-Danlos type 4, adult polyscystic kidney disease, hypertension, smoking
What are the causes of intracerebral hemorrhage?
common causes: hypertension, trauma, infarction
Primary auditory cortex corresponding Brodmann areas?
41 & 42
Broca’s area corresponding Brodmann area?
44 & 45
Frontal eye field corresponding Brodmann area?
area 8
Premotor cortex corresponding Brodmann area?
area 6
Primary motor cortex corresponding Brodmann area?
area 4
Primary somatosensory cortex corresponding Brodmann area?
areas 3, 1, and 2
Angular gyrus corresponding Brodmann area?
area 39
Wernickes area corresponding Brodmann area?
area 22
What would a lesion of the frontal eye field lead to?
inability to make voluntary eye movements toward the contralateral side
Because the activity of thee intact frontal eye field in the opposite cortex would also be unopposed after such a lesion, the result is conjugate slow deviation of eyes toward side of the lesion.
Intact frontal eye field in the opposite hemisphere deviates eyes away from the paralyzed limb
What is Gerstmann Syndrome?
when a lesion is confined to anuglar gyrus ( found in the parietal lobe)
Symptoms: produces loss of ability to comprehend written language (alexia) and to write it (agraphia)
Often presents with 3 other conditions: acaclulia
finger agnosia
left-right disorientation
Describe conduction aphasia?
- the large fiber bundle called the superior longitudinal fasiculus (or the arcuate fasiculus) is lesioned.
- verbal output is fluent, but there are many parapharases and word finding pauses.
- Both verbal and visual language comprehension; but if asked to repeat words or execute verbal commands cant be done….
- also poor object naming example of “disconnect syndrome”
- Disconnect syndrome because of inability to send information from one cortical area to another
Transcortical apraxia.
similar to conduction aphasia except 2 hemispheres are disconnected because of lesion at the corpus callosum
Asomatognosia.
caused by lesions in the non-dominant right parietal lobe may result in unawareness or neglect of the contralateral half of the body
What is visual agnosia?
when there is damage to parts of the temporal lobes involving the cone stream producing a visual agnosia.
Inability to recognize visual patterns (including objects) in the absence of a visual field deficit
lesions in the temporal lobe that also produce some destruction of adjacent occipital lobe in either hemisphere result in prosopagnosia specific inability to recognize faces
Alexia without agraphia?
“higher-order” deficit associated with occipital lobe damage is alexia without agraphia (or pure word blindness)
Patients unable to read at all and often have color anomia (inability to name colors)
can write
another example of disconnect syndrome in which information from occipital lobe is not available to the parietal or frontal lobes to understand or express what is seen
involvement of splenium of corpus callosum prevent visual informatin from intact right occipital cortex from reaching languate comprehension centers in left hemisphere
Arterial supply to the anterior limb of the internal capsule?
medial striate br. of ACA
What are the tracts reaching the anterior limb of the internal capsule?
thalamocortical
Arterial supply to the genu of the internal capsule?
lenticulostriate br. of MCA
What are the tracts through the genu?
corticobulbar
Arterial supply to the posterior limb of the internal capsule?
lenticulostriate branch of MCA
Tracts through the posterior limb of the internal capusle?
corticospinal, all somatosensory thalamocotical projections
Where is the second most common site of aneurysm in the brain?
posterior communicating artery
Posterior communicating artery blockage can cause blockage of what cranial nerve?
CN III
Gaze palsy aphasia is seen with which branch of the middle cerebral artery?
lenticulostriate branch
What part of the brain is implicated in frontal lobe syndrome? What is frontal lobe syndrome?
prefrontal cortex;
symptoms can include poor judgment, difficulty concentrating and problem solving, apathy, inappopriate social behavior
What is the lobe implicated in contralateral asterognosis/ apraxia?
superior parietal lobe
What are the lobes implicated in Gerstmann syndrome?
Inferior parietal lobule
(angular gyrus; area 39)
What structure is implicated in Kluver bucy syndrome?
amygdala
What are some symptoms of Kluver Bucy?
hyperphagia, hypersexuality, visual agnosia
