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Neuroscience > Lab 2 - Internal Anatomy of the Brain and Ventricles > Flashcards

Lab 2 - Internal Anatomy of the Brain and Ventricles Flashcards

1
Q

what make up the basal ganglia? where is it? what is it involved in?

A

subcortical nuclei: caudate, putamen, and globus pallidus (substantia nigra and subthalamic nucleus are also part of BG, but not subcortical nuclei)

  • caudate + putamen = striatum
  • deep structures of forebrain involved in motor control and cognitive functions
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2
Q

what do diseases of the basal ganglia cause?

A

variety of motor symptoms

  • akinesia (difficulty initiating movement)
  • rigidity (abnormal muscle tone)
  • tremor/chorea/ballism (development of various involuntary motor movements)
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3
Q

what is the amygdala?

A

a subcortical nucleus involved in controlling emotional behavior, and part of limbic system

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4
Q

what does the limbic system include?

A

limbic lobe, amygdala, anterior cingulate gyrus, orbital and medial prefrontal gyri, ventral basal ganglia, hippocampus, thalamus

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5
Q

where do the fibers of the corpus callosum form ventricular roof?

A

dorsal surface of lateral ventricles

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6
Q

what lies of the floor of the anterior horn of the lateral ventricle?

A

a cavity created by the head of the caudate nucleus

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7
Q

what produces the hollow on the ventral medial surface of inferior horn?

A

hippocampus

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8
Q

what does the BBB do?

A

maintain a stable environment for neurons to function effectively

  • protects CNS from severe fluctuations in ionic concentrations
  • excludes toxic compounds
  • protects central neurons from circulating hormones and neurotransmitters released in other parts of the body
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9
Q

what is the actual locus of the BBB, and how is it specialized?

A

in the capillary endothelium

  • has tight junctions between capillary endothelial cells
  • few endocytic vesicles for intracellular transport
  • high number of mitochondria indicative of high levels of oxidative metabolism
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10
Q

how is entry to brain achieved?

A
  1. diffusion of lipid-soluble substances related to oil/water partition coefficient
  2. facilitative and E-dependent transport of specific water soluble substances
  3. ion channels
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11
Q

how is exit from the brain achieved?

A

reverse pump, intracellular transporters within astroglia

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12
Q

when does the BBB break down?

A

brain tumors, bacterial invasion, and most commonly ischemia

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13
Q

what does pathology of stroke stem from?

A

loss of tissue oxygenation, introduction of toxins to brain, and ionic fluxes

  • directly damages Na and K pumps, which with ionic influx causes cells to fill with water
  • resulting edema increases intracranial pressure to cause coma and death
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14
Q

what does CSF do?

A

is in equilibrium with brain ECF, and maintains constant external environment for cells of CNS, preserving homeostasis

  • provides buoyancy for brain, decreasing weight on skull
  • serves as mechanical cushion, protecting from impact with skull
  • drains unwanted substances from brain, serving as brain’s lymphatic system
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15
Q

what is the total volume, rate of formation, and turnover of CSF?

A

total volume: 140 mL
rate of formation: 500 mL/day
turnover: 3-4 times a day

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16
Q

what is the choroid plexus?

A

specialized capillary network surrounded by cuboidal/columnar epithelium that secretes CSF
-maintains chemical stability of CSF

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17
Q

what accounts for continuous production of CSF and active transport of metabolites out of CNS and into blood?

A

epithelial cells of choroid plexus form carrier that is responsible for carrier-mediated, bi-directional active transport
-capillaries are also freely permeable to plasma solutes

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18
Q

where is the choroid plexus found?

A

floor of inferior horn, body of lateral ventricle, roof of third ventricle, and inferior part of roof of 4th ventricle

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19
Q

how does CSF from choroid plexus flow?

A
  1. that made in body of lateral ventricle flows into 3rd ventricle
  2. joined by CSF from roof of 3rd ventricle, flows through cerebral aqueduct to 4th ventricle
  3. exits through 1 foramen of Magendie (lidline opening at caudal end of 4th) and 2 foramina of Luschka (lateral edge of ventricle at widest extend where CN VIII is)
  4. flows over entire brain and SC in subarachnoid space until arachnoid villi in dural sinuses (esp. superior sagittal sinus)
20
Q

what causes obstructive (non-communicating) hydrocephalus?

A

CSF flow being obstructed at interventricular foramen, cerebral aqueduct, or outlet of 4th ventricle (narrowest)

21
Q

what causes communicating hydrocephalus?

A

no blockage of ventricular flow, but arachnoid villi are diseased and absorption fails

22
Q

how can increased intracranial pressure be seen clinically?

A

inspecting fundus of eye with opthalmoscope (papilledema)

  • retinal vessels of optic nerve are engorged
  • optic nerve becomes dilated
  • also headache, nausea, vomiting, cognitive impairment, decreased level of consciousness, impaired vision, and 6th nerve palsies)
23
Q

what is and what causes magnetic gait?

A

unsteady gait where feet barely leave the floor

-compromised frontal lobe function, including descending white matter pathways from frontal lobe

24
Q

how is CSF changed in MS?

A

gamma globulin content is increased to more than 13% total PRO due to production of immunoglobulin

25
Q

what are RBC in CSF indicative of?

A

hemorrhagic stroke in CNS

26
Q

what are the 3 categories of deep white matter tracts, and what do they connect?

A
  1. association fibers - connect different areas of cortex in same hemisphere
  2. commisural fibers - connect homologous areas of cortex of 2 hemispheres
  3. projection fibers - connect areas of cortex to lower areas of neuraxis
27
Q

what kind of symptoms does damaging the white matter that connects areas of cortex produce?

A

similar symptoms as damaging area of cortex itself

28
Q

what are the 4 (long) association fiber tracts?

A
  1. superior longitudinal fasciculus (AKA arcuate fasciculus) - the largest
  2. inferior longitudinal fasciculus
  3. uncinate fasciculus
  4. cingulum
29
Q

what is the superior longitudinal fasciculus? where is it? what does it connect?

A

longest association fiber tract (AKA arcuate fasciculus)

  • extends from frontal lobe, arcing inferiorly into temporal lobe and posteriorly to occipital lobe
  • connects Broca’s motor speech area, Wernicke’s area, and auditory cortex
30
Q

what is the inferior longitudinal fasciculus? where is it?

A

association fiber tract that extends from occipital lobe to temporal lobe along inferior aspect of hemisphere deep to occipitotemporal gyrus

31
Q

what is the uncinate fasciculus? where is it? what does it connect?

A

association fiber tract that runs deep to limen insulae

-connects frontal (cortex-based reward and punishment centers) and temporal (lobe-based memory representations) cortices

32
Q

what is the limen insulae?

A

anterior border of the insula

33
Q

what is the cingulum? where is it? what does it connect/

A

association fiber tract on medial aspect of hemisphere deep to cingulated gyrus

  • connects structures of limbic system (subcallosal gyrus, cingulate gyrus, parahippocampal gyrus, uncus) and thalamus fibers (receive pain fibers from spinothalamic tract)
  • -hypothesized to be involved in process of learning to avoid painful stimuli
34
Q

are association fiber systems one-way?

A

no, they are bidirectional and can travel short or long distances
-reciprocal connections are rule, rather than exception

35
Q

what are the 4 commissural fibers?

A
  1. corpus callosum (largest)
  2. anterior commissure
  3. hippocampal commisure
  4. posterior commissure
36
Q

what is the corpus callosum? what does it connect?

A

the largest commissural fiber tract

  • interconnects homologous areas of hemispheres in spatially oriented fashion
  • genu: connects frontal lobes
  • body: connects parietal lobes
  • splenium: connects occipital lobes (notably visual cortex)
37
Q

what is the anterior commissure? what does it connect?

A

commissural fiber tract that connects anterior poles of two temporal lobes containing primary olfactory cortices

38
Q

what is the hippocampal commissure? what is it made of? what does it connect?

A

commissural fiber tract made of axons of fornix that cross when they approach each other (crura), between splenium of corpus callosum and posterior thalamus
-connects the hippocampi (consolidation of long-term memory)

39
Q

what is the posterior commissure? what does it connect? what is it involved in?

A

commissural fiber tract that connects the two sides of rostral midbrain
-involved in pupillary light reflex for upwards gaze

40
Q

what are the projection fibers?

A
  1. corona radiata
  2. internal capsule
  3. crus cerebri
41
Q

what is the corona radiata? what are their interconnections called?

A

projection fiber axons in cerebral hemispheres (radiate to all areas of cortex)

  • thalamic radiations are interconnections between thalamic nuclei and cortical targets
  • -include sensory projections (somatosensory, visual, and auditory) from sensory nuclei of thalamus to respective cortical centers in parietal, occipital, and temporal lobes
42
Q

what is the internal capsule?

A

projection fiber axon continuations of corona radiata as they pass medial to lenticulate nucleus

43
Q

what is the crus cerebri?

A

projection fiber axons that descend onto anterior aspect of midbrain whose targets are in the brainstem and spinal cord

44
Q

what kind of fibers do internal capsule and crus cerebri contain?

A
  • corticospinal fibers (axons originating in pre/post central gyri to dorsal and ventral horn neurons in spinal cord)
  • corticobulbar fibers (motor axons that control cranial nerve nuclei in brainstem)
  • corticopontine fibers (axonsfrom motor cortex to pontine nuclei in base of pons, which project to contralateral cerebellar hemisphere)
45
Q

what are the components of the lenticular nucleus?

A

putamen (laterally) and globus pallidus (medially)

Neuroscience (39 decks)

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