Telencephalon and Diencephalon Flashcards Preview

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Flashcards in Telencephalon and Diencephalon Deck (52):
1

describe the folding of the neural tube

  • prosencephalon (forebrain)
  • mesencephalon (midbrain)
  • rhombencephalon (hindbrain)
  • developed from the back forward

2

what are the derivatives of the prosencephalon?

forebrain

  • telencephalon: cerebral hemispheres, surrounds the lateral ventricles
  • diencephalon: epithalamus (pineal), thalamus, hypothalamus, optic cup/nerves, surrounds the 3rd ventricle

3

describe the ventricles of the brain

  • R and L lateral ventricles, third ventricle, fourth ventricle
  • connected by foramina
  • filled with CSF, contains choroid plexus (produces CSF, is located in every ventricle)

4

describe ventricle development and association to key brain regions

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5

what is CSF?

  • continuously produced in the ventricles
  • high in sodium, low in potassium (these create chemical gradients)
  • no protein (the presence of protein is usually indicative that there is a problem)

6

what are the 3 main purposes of CSF?

  • buoyancy
  • protection (positive pressure, cushion)
  • chemical stability (high sodium, nutrients, etc.)

7

describe the volume of CSF 

  • total adult volume is ~100-150ml
  • replaced about 4 times each day (~500ml daily)

8

describe the flow of CSF

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9

what are meninges?

  • a system of membranes which envelops the centeral nervous system
  • 3 layers - dura mater, arachnoid mater, pia mater
  • protect organs from rubbing against bones of the skull and spine

10

describe the meningeal layers

dura mater - dura

leptomeninges (layers and a space):

  • arachnoid - a barrier
  • subarachnoid space - CSF
  • pia - vessels run in this layer and penetrate the cortex

11

what is obstructive hydrocephalus?

  • obstruction of the CSF flow that causes buildup of CSF in ventricles
  • can be reversed with the use of a splint

12

which two main arteries supply blood to the brain?

  • internal carotid artery
  • vertebral arteries

13

name the branches of the internal carotid artery and vertebral arteries that supply the brain

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14

describe vertebrobasilar and carotid circulation

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15

find the posterior cerebral a., basilar a., internal carotid a., anterior spinal a., and vertebral a.

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16

which arteries supply each colored area of this brain?

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  • yellow - anterior cerebral artery
  • red - middle cerebral artery
  • blue - posterior cerebral artery

17

what is the blood brain barrier?

  • composed of high-density cells connected by tight junction that restrict passage of substances from the bloodstream
  • it allows diffusion of small hydrophobic molecules (O2, CO2, hormones)
  • cells actively transport metabolic products such as glucose across the barrier with specific proteins

18

describe characteristics of an epidural hematoma

  • between skull and dura mater
  • dura peels off skull, space fills with arterial blood
  • compresses brain
  • usually a result of a skull fracture and torn middle meningial artery

19

describe characteristics of a subdural hematoma

  • occurs below the dura mater in the subdural space
  • dura still attached to skull
  • venous blood fills subdural space and compresses brain
  • result of a torn bridging cerebral vein

20

what is a subarachnoid hemorrhage?

  • commonly occur as a result of rupture of an a. in the circle of willis
  • between arachnoid mater and pia mater; subarachnoid space

21

what is the telencephalon? what are its 4 main divisions?

  • cerebral cortex
  • frontal lobe, parietal lobe, temporal lobe, occipital lobe

22

what 2 structures are inside the telencephalon?

basal ganglia and limbic system

23

what are Brodmann's areas?

regions of the cerebral cortex that are defined by a number

24

what is a commissure?

reciprocal connections

25

what is a chiasma?

crossing and/or intersection of two tracts

26

what is decussation?

cross-over of independent tracts at the same site (form an X)

27

what are "crossing fibers"?

ill-defined fibers whose principal direction may not be defined

 

28

what is a fascicle?

a bundle

29

what is a fasciculus?

a bundle of fibers

30

describe the diencephalon

  • surrounds the third ventricle
  • major divisions: epithalamus, thalamus, hypothalamus, "sub thalamus"

31

describe the epithalamus

  • pineal (serotonin/sleep)
  • habenula (negative feedback to reward)
  • posterior commissure - pupillary light reflex

32

describe the thalamus

  • major "relay" nuclei
  • on either side of 3rd ventricle

33

describe the hypothalamus

  • endocrine/physiological stasis
  • surrounds the anterior portion of the third ventricle

34

label these portions of the hypothalamus

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35

what are the 4 subregions of the hypothalamus?

  • preoptic area
  • suprachiasmotic (anterior) region
  • tuberal (middle) region
  • mammillary (posterior) region

36

what does the hypothalamus control?

  • autonomic
  • endocrine
  • emotional
  • somatic

37

describe the basal ganglia

  • sits on top of (dorsal to) the diencephalon
  • extrapyramidal motor system
  • modulates the initiation, termination, and amplitude of intentional movements

38

describe the two main components of the modulatory cortical loop

  • basal ganglia afferents - robust input from almost all parts of the cortex
  • basal ganglia efferents - ventral thalamic relay to cortex; others - superior colliculus, forebrain, limbic
  • somatic motor loop: somatomotor control; occulomotor loop (eye movements), frontal loop (cognitive functions), and limbic loop (emotional and visceral functions

39

what are the 5 major nuclei of the basal ganglia?

  • caudate nucleus
  • putamen
  • globus pallidus
  • subthalamic nucleus
  • substantia nigra 

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40

what forms the striatum?

the caudate and the putamen

41

what forms the lentiform nucleus?

putamen and globus pallidus

42

what are the two subdivisions of the substantia nigra?

  • pars compacta
  • pars reticulata

43

describe the blood supply to the basal ganglia

  • branches of the anterior and middle cerebral artery (remember these come from the internal carotid artery)

44

what is hyperkinesia?

excessive abnormal movements, often with increasing dementia

example: Huntington's disease

  • chorea
  • hemiballism

45

describe Huntington's disease

  • type of hyperkinesia
  • cause: genetic
  • loss of striatal projection neurons
  • anatomy: striatal atrophy

atrophy of putamen: chorea
atrophy of caudate: dementia

46

what is chorea?

involuntary, quick, jerky, irregular movements:

  • major chorea
  • minor chorea (Sydenham's chorea): associated with rheumatic fever

47

what is hemiballism?

  • repetitive, but constantly varying, large amplitude involuntary movements of the proximal parts of the limbs
  • decrease activity of the subthalamic nucleus

48

describe hypokinesia

overall decreased bodily movements

example: Parkinson's disease

49

describe Parkinson's disease

  • hypokinesia
  • cause: genetic/environmental/idiopathic
    loss of substantia nigra dopamanergic projection neurons to the striatum
  • symptoms: bradykinesia, rigidity, tremor at rest

50

what is the circuit of Papez?

part of the limbic system

 

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51

what is wernicke-korsakoff syndrome?

  • limbic amnesia
  • cause: vit B1 deficiency and alcoholism
  • site: mammillo-thalamic tract disruption (no damage to hippocampus)
  • symptoms:
    inability to form new memories
    loss of memory, can be severe
    hallucinations
    confabulation (make up stories)

52

describe alzheimer's disease

  • limbic amnesia
  • bilateral medial temporal lobe damage
  • common hippocampal deficits:
    amnestic/inability to form new memory
    reduced motivation
    troubles navigating familiar places
    general cognitive impairment (often mild)