ICL 2.3: Overview of the Human Brain Flashcards

1
Q

what is the grey matter of the brain?

A

aka the cerebral cortex!! it’s the outer most layer of the brain

it’s the neuron cell bodies

ex. ganglia and nuclei

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

what is the white matter of the brain?

A

aka the cerebral white matter; it’s the inner layer of the brain under the cerebral cortex

the myelinated axons from the neuron cell bodies

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

what are the 3 poles of the brain?

A
  1. frontal pole
  2. temporal pole
  3. occipital pole

they are found in the anterior, middle and posterior cranial fossas, respectively

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

what would the brain of someone with Alzheimer’s or dementia look like?

A

the gyri and sulci wouldn’t be tight

the sulci would be dilated and the gyri would be small and atrophied

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

which sulcus seperates the frontal and parietal lobes?

A

central sulcus

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

what would cause the brain to be flattened?

A

edema

edema in the cranial cavity could cause the lobes of the brain to become squished against the skull and appear flattened

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

what are the gyri of the frontal lobe?

A
  1. superior frontal gyrus (closest to midline)
  2. middle frontal gyrus
  3. inferior frontal gyrus
  4. precentral gyrus

slide 14; go look at the picture

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

what are the subdivisions of the inferior frontal gyrus?

A
  1. pars opercularis
  2. pars triangularis
  3. pars orbitalis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what are the sulci of the frontal cortex?

A
  1. superior frontal sulcus
  2. inferior frontal sulcus
  3. precentral sulcus (superior and inferior)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the importance of the central sulcus?

A

it separates the frontal lobe from the parietal lobe but more importantly it separates functional areas!

the motor cortex fibers all originate from the frontal lobe while all the sensory information we receive is in the parietal lobe

so when a patient has a tumor one of the things the surgeon will do is identify the central sulcus to find the somatosensory cortex of the parietal love vs. the motor cortex of the frontal lobe

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

what are the gyri of the parietal lobe?

A
  1. postcentral gyrus
  2. superior parietal lobule
  3. inferior parietal lobule

the inferior parietal lobule is comprised of the supramarginal gyrus and the angular gyrus

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

how can you locate the specific gyri of the inferior parietal lobule?

A

the inferior parietal lobule is composed of the supramarginal gyrus and the angular gyrus

if you follow the superior temporal gyrus it will lead you to the supramarginal gyrus

if you follow the superior temporal sulcus it will lead you to the angular sulcus

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

what are the sulci of the parietal lobe?

A
  1. postcentral sulcus

2. intraparietal sulcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what are the gyri of the temporal lobe?

A
    1. superior temporal gyrus
  1. middle temporal gyrus
  2. inferior temporal gyrus
  3. fusiform gyrus (underneath)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the sulci of the temporal lobe?

A
  1. superior temporal sulcus

2. inferior temporal sulcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the tentorium cerebelli?

A

it’s the dural reflection that the occipital lobe sits on

it covers the cerebellum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the insula?

A

aka the insular cortex

you can find it deep to the frontal and temporal lobes and it’s like a second mini brain = “hidden lobe”

people think that pain and auditory elements are processed here as well

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what structure separates the left and right hemisphere?

A

longitudinal cerebral fissure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

which structure separates the temporal lobe from the frontal and parietal lobes?

A

lateral sulcus aka fissure of sylvius

if you dissected through the lateral sulcus you’d find the insural cortex

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

what is the function of Broca’s area?

A

execution and fluency of speech

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

what is the function of Wernicke’s area?

A

comprehension of speech

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is conductive aphasia?

A

Broca’s area and Wernicke’s area have to be in constant communication in order for you to understand what is being said to you and respond back

so if there’s a disruption between them then you get conductive aphasia

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

which sulcus splits the occipital lobe into superior and inferior portions?

A

calcarine sulcus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

which sulcus separates the occipital and parietal lobes?

A

parieto-occipital sulcus

you can only see on a sagittal cut of the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are commissures? what are the two commissures of the brain?

A
  1. corpus callosum
  2. anterior commissure

commissures are points of connection between the right and left hemispheres so that they can communicate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what is the corpus callosum?

A

a commissure of the brain that’s a large bundle of axons connecting left and right cerebral hemispheres

when tumors metastasize from one side of the brain to the other it’s because they use the corpus callosum to get there

a thin corpus callosum indicates white matter atrophy or degeneration of myelin

side note: on a coronal section you will only see the corpus callosum once but in the sagittal section you’ll see the whole curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what is the anterior commissure?

A

a small bundle of axons that passes between the two cerebral hemispheres joining the grey matter of the anterior poles of the temporal lobes

28
Q

what is the internal capsule? what is it bordered by?

A

a collection of myelinated fibers

it has 3 subdivisions and unique fibers travel through each division each with their own function

it is bordered by the caudate nucleus, globus pallidus, thalamus, and putamen

go look at the picture

29
Q

what is the basal ganglia?

A

caudate nucleus + putamen + globus pallidus

it helps you execute smooth rhythmic movement

ex. Huntington’s is a disease of the basal ganglia and so they have lots of movement problems

30
Q

what are the subdivisions of the internal capsule?

A
  1. anterior limb
  2. genu
  3. posterior limb

only in an axial image would you be able to see all 3 of these

31
Q

which fibers are located in the genu of the internal capsule?

A

corticobulbar fibers

these are involved in motor function

32
Q

which fibers are located in the posterior limb of the internal capsule?

A

corticospinal fibers

involved in motor supply

33
Q

what is the diencephalon?

A

fancy word for the thalamus + hypothalamus

34
Q

what dura covers the hypophyseal fossa?

A

diaphragma sellae

35
Q

what controls the pituitary gland?

A

the hypothalamus

so the hypothalamus is super close to the pituitary gland, it’s only seperated by the pituitary streak

this means the hypothalamus is in close proximity to the sellea turcica

36
Q

what part of the brain must all afferent sensory information pass through?

A

the thalamus

ALL information that comes from the outside world has to stop at the thalamus and then the thalamus sends it out to the right area of the brain to be processed

so basically the thalamus is a relay station and it has specific nuclei that will route information to specific areas of the brain

37
Q

what structure separates the thalamus from the hypothalamus?

A

hypothalamic sulcus

38
Q

what are the 3 subdivisions of the brainstem?

A
  1. midbrain
  2. pons
  3. medula
39
Q

what are the 4 ventricles in the brain?

A

2 lateral ventricles

3rd ventricle

4th ventricle

note: the lateral ventricle is found in every aspect of the brain; the frontal, temporal and occipital horn!

40
Q

what is the function of the ventricles of the brain?

A

CSF flows through the ventricles!

it flows from the ventricles of the brain to the subarachnoid space in the spinal cord

lateral ventricle –> 3rd ventricle –> 4th ventricle –> subarachnoid space

CSF leaves 4th ventricle via foramen of magendie (caudal end) & foramina of Luschka (lateral angles of ventricle) to enter subarachnoid space

41
Q

what structure connects the lateral ventricle with the 3rd ventricle?

A

interventricular formamen

42
Q

what structure connects the 3rd ventricle to the 4th ventricle?

A

cerebral aqueduct

43
Q

what structure resides inside the lateral ventricle?

A

the choroid plexus

this produces CSF

44
Q

what separates the anterior horn of the lateral ventricle into left and right?

A

septum pellucidum

45
Q

how could a brain tumor beneath the tentorium cerebelli effect the brain?

A

the tentorium cerebelli is the dura matter that separates the cerebellum from the occipital lobe

if there’s an infratutorial tumor below the tentorium cerebelli it’s putting pressure on the ventricles; specifically the cerebral aqueduct –> most pediatric brain tumors are infratutorial while most adult ones are supratutorial

the problem is that just because there’s a tumor doesn’t mean that the brain will stop making CSF so the 3rd ventricle will probably get huge since the tumor is compressing on the cerebral aqueduct and not allowing it to drain

so what happens is the brain tissue starts to compressed against the skull and get damaged…

the take-home message is that if you have a block at either connection between the ventricles you will end up with serious problems

46
Q

how is the cerebral cortex organized?

A

the cerebral cortex is the grey matter of the brain and it’s organized into 6 layers

all the layers communicate with each other

layer 3 and 5 are the important ones

47
Q

what is the function of layer 3 of the cerebral cortex?

A

cortical-cortical connections

aka commissural and association fibers

so layer 3 is important for developing connections so that different parts of the brain can communicate with each other

48
Q

what is the function of layer 5 of the cerebral cortex?

A

it sends output to subcortical structures like the pons, brainstem, basal ganglia, and spinal cord

so it’s what helps form pathway like the corticospinal pathway and corticobulbar pathway

it’s composed of long projection fibers out of the cerebral cortex

the neurons in the cortex of the brain are considered UPPER motor neurons

49
Q

what are the two upper motor neuron pathways?

A
  1. motor cortex (M1)

2. premotor cortex (M2)

50
Q

what is the function of the motor cortex?

A

part of the frontal lobe that evokes movement of individual muscles, and is arranged in a somatotopic fashion (homunculus)

most axons of the Pyramidal tract originate here.

51
Q

what is the function of the premotor cortex?

A

part of the frontal lobe that evokes mass movements involving postural adjustments both ipsilaterally and
contralaterally

most extrapyramidal pathways originate in the premotor cortex

lesions in this area result in spasticity of contralateral antigravity muscles due to the loss of inhibition provided by upper motor neurons in this area

52
Q

describe the pathway of the motor homunculus

A

M1 in the frontal lobe –> posterior limb of the internal capsule –> midbrain –> pons –> mid medulla –> caudal medulla

once the signal reaches the caudal medulla, the fibers cross over before ending the spinal cord

so if you had an upper motor neuron lesion in the cortex of the brain, your symptoms and muscle weakness would be on the contralateral side of the body!!

if in turn, you had a lower motor neuron lesion in the ventral horn of the spinal cord, your deficits would be ipsilateral

53
Q

what are the 3 types of pyramidal cells?

A
  1. projection
  2. association
  3. commissural

the white matter in the brain consists of large numbers of myelinated axons (fibers) carrying electrical signals between areas of within the brain and between the brain and the rest of the body –> functionally, there are three major types of white matter fibers in the CNS: Projection Fibers, Association Fibers, and Commissural Fibers

54
Q

what is a projection fiber?

A

project OUTSIDE of cortex – to the thalamus or basal ganglia or brainstem or spinal cord

55
Q

what is an association fiber?

A

send axons to another cortical region in the SAME hemisphere

56
Q

what is a commissural fiber?

A

send axons to cortical regions in the OPPOSITE hemisphere

57
Q

what is a very important example of association fibers?

A

association fibers connect different parts of the same cerebral hemisphere

for example, Broca’s area and Wernicke’s area connected by the arcuate fasciculus which is a type of association fiber

because of this connection patients with lesions in either Broca’s or Wernicke’s area will have impaired repetition = conduction aphasia

damage to the arcuate fasciculus impairs the transmission of information between Wernicke’s area andBroca’sarea; this injuryleads to impaired repetition

thus, the patient can comprehend the speech but cannot transmit the information the speech production centers in Broca’s area to allow repetition to occur

58
Q

are neurons glial cells?

A

NO

glial cells are supporting cells

59
Q

what is an astrocyte?

A

part of the CNS

  1. structural support
  2. transport of substances from blood to neurons
  3. react to injury

most brain tumors are astrocytomas

60
Q

what is an oligodendrocyte?

A

part of the CNS

  1. they form the myelin sheaths around axons in the CNS – multiple axons per oligodendrocyte

this means that the loss of just one oligodendrocyte is a big deal because that means no myelin for 50-100 axons

  1. provide nutritive functions in gray matter
61
Q

what is a microglia?

A
  1. immune function; basically a macrophage – have lots of lysosomes, inclusions and vesicles that release damaging and neuroprotective chemicals
  2. react to injury

they’re small, elongated nuclei with twisted processes

62
Q

what is an ependymal cell?

A

part of the CNS

they line ventricles

they’re a single layer of cuboidal-to-short columnar epithelium that line the ventricles of the brain and the central canal of the spinal cord

they’re bound by junctional complexes on the apical side

they also have cilia and microvilli that facilitate the movement and absorption of the CSF

63
Q

what are satellite cells?

A

part of the PNS

they have support functions similar to astrocytes

64
Q

what are Schwann cells?

A

the cells in the PNS that form myelin around the axons on the pNS

65
Q

what happens when an astrocyte reacts to an injury?

A

you could end up with severe astrogliosis

normally the astrocyte cell body is flat which means there’s nothing going on but when they’re activated by injury they start to plump up

if there’s a ton of damage to axons like with a patient who has MS and there’s a lot of myelin degeneration around the axon, the astrocytes will occupy the empty space left behind by the myelin and this is how you end up with a glial scar in the brain tissue

66
Q

how can you histologically identify an oligodendroglioma?

A

the tissue will be composed of round cells with blue nuclei and a rim of clear cytoplasm

so the oligodendrocytes look like they’re surrounded by cytoplasm and they usually aren’t…