Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Building Brains > Structure and organisation > Flashcards

Structure and organisation Flashcards

1
Q

Outer meningeal layer

A

Dura mater (tough mother)
Tough, protects the brain
Reflections to support the brain: Falx cerebri (divides hemispheres) and tentorium cerebelli (divides occipital lobe from cerebellum

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

Middle meningeal layer

A

Arachnoid mater (Spider mother)
Blood vessels and CSF
Granulations drain fluid into venous system

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

Inner meningeal layer

A

Pia mater (tender mother)
follows contours of brain
delicate and difficult to see on images

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

Types of meningeal haematoma

A

Sub-arachnoid - blood pools in sub-arachnoid space causing lots of pressure on the brain

Subdural - blood pools just below dura mater, pressure on one spot on the brain

Epidural - above dura, less pressure on the brain, normally due to external trauma

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

What is CSF?

A

Cerebrospinal Fluid
Colourless liquid bathing the brain, produced in choroid plexus (cells lining ventricles)
Assists in circulating substances, provides cushioning and absorbs shock
approx 150ml exchanged 3 times a day

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

Circulation of CSF through ventricular system

A

Lateral Ventricle to 3rd Ventricle through the inter-ventricular foramen
3rd to 4th ventricle through cerebral aqueduct
Down to cisterns and sub-arachnoid space
circulated and reabsorbed by arachnoid granulations

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

Cerebral Blood Supply - Where does each artery supply blood to?

A

Inferior Posterior Cerebellar - posterior cerebellum
Inferior anterior cerebellar - anterior cerebellum
Basilar Artery - brain stem, merged from vertebral arteries, sits on top of pons
Superior cerebellar - majority of cerebellum
Posterior cerebral - medial occipital, inferior temporal lobe, hippocampus
Anterior cerebral - medial frontal lobe, corpus callosum
Middle cerebral - lateral/temporal/parietal, posterior frontal lobe

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

Blood Brain Barrier

A

Oxygen, CO, glucose, some amino acids can pass into brain; pathogens/antibodies can’t
Layer of endothelial cells with tight junctions
Pericytes assist with maintenance
Astrocyte end feet projections wrap around and provide extra layer of barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Cortical Neurones - Pyramidal

A

body is 10-50micrometers (big)
1 axon from base of pyramid
Many denrites (sometimes called spiny)
Excitatory - glutamatergic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Cortical neurones - Granule cells

A

Soma is <10micrometres
GABAergic inhibitory interneurones
Don’t project anywhere

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

Glial cells - astrocytes

A

Star shape
End feet can wrap around blood vessels
Maintain homeostasis
Form barrier around brain wound - repair, scarring

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

Glial cells - Microglia

A

Immune, fine processes during rest
Mobile when activated - change structure
Produce enzymes and cytokines
Capable of phagocytosis
Modulate inflammation of brain

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

Glial cells - Oligodendrocytes

A

Small cells
Processes myelinate different axons
Make up white matter

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

Golgi vs Nissl

A

Golgi doesn’t stain all cells but stains whole cell
Nissl stains RNA, stains all cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cortical Layers

A
  1. Molecular - some neurones, glial cells, apical dendrites
  2. External granular - small pyramidal, granular neurones
  3. External pyramidal - small/medium pyramidal and granular
  4. Internal granular - dense, mostly stellate neurones, some pyramidal
  5. Internal pyramidal - dense, large pyramidal, apical and basilar dendrites
  6. Multiform - small spindle-like pyramidal
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Brodmann’s areas

A

1-3 Primary somatosensory area (postcentral gyrus)
4 Primary motor area (precentral gyrus)
5,7 Somatosensory association areas (Superior parietal lobule, supramarginal gyrus)
5 Premotor area (middle frontal gyrus)
22 Wernicke’s area and 41 Primary auditory area (superior temporal gyrus)
44,45 Broca’s area (Inferior frontal gyrus)

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

Aphasia: Definition and types

A

Disruption of language and/or speech
Broca’s - Expressive, failure to formulate
Wernicke’s - Receptive, failure to comprehend, inappropriate context but some connection being made

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

Difference between association and commissural fibres

A

Association fibres exchange information within one hemisphere (ipsilateral)
Commissural fibres exchange information between hemispheres (contralateral)

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

4 commissural fibres

A

Corpus callosum - connects all cortices, runs anterior to posterior, facilitates the majority of communication between hemispheres
Fornix - connects the hippocampus to the hypothalamus and mammillary bodies
Anterior commissure - connects temporal lobes specifically amygdala
Posterior commissure - connects bilateral midbrain nuclei

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

Internal capsule

A

Point where white matter starts to converge before continuing to the spinal cord
Kind of sits in middle of basal ganglia
Common location for stroke - very bad

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

Projection fibres

A

Connect cortices to other brain structures, SC

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

Pyramidal tracts

A

Corticobulbar - terminates in brain stem, moves head/neck/face
Corticospinal - terminates in spinal cord, (80% crosses at Lower medulla, 20% on same side)

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

Motor neuron syndromes

A

UMN -hypertonia due LMN going crazy without information so go spontaneously and build tone
LMN - hypotonia, inhibited stretch reflexes and spontaneous firing cause individual muscle fibre contractions, potentially twitching

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

What makes up the basal ganglia

A

Caudate nucleus
Putamen
Globus pallidus (internal and external)
Subthalamic nucleus
Substantia nigra (pars reticulata and pars compacta)

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

What are the 4 lobes and their functions?

A

Frontal (personality, attention, motivation, movement)
Parietal (integrating sensory information, language)
Temporal (memory, sensory processing, language)
Occipital (vision)

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

What are the sulci from the sagittal view?

A

Lateral (separates temporal from frontal and parietal lobes) - prominent horizontal
Precentral (Anterior to central sulcus) - deepest one towards the front
Central (Separates frontal from parietal) - behind precentral, not as deep
Parieto-occipital (Separates parietal from occipital) - back of brain

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

What are the 4 bumps on the posterior side of the midbrain?

A

Inferior and Superior Colliculi
Superior = part of unconscious visual system that allows us to respond quickly to stimuli
Inferior = part of auditory system; play role in localising sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the striatum (neostriatum)?

A

Caudate and Putamen
Striated appearance because of some white matter fibres
Receives all main input to basal ganglia (glutamatergic from thalamus/cortex and dopaminergic from SNc)
90% are GABAergic medium spiny neurones - inhibitory - one very long axon to innervate other structures
Striatal afferents: Corticostriatal (Glut), Thalamostriatal (Glut) and Nigrostriatal (D)
Striatal efferents: Stratopallidal (GABA - direct and indirect to different part of GP) and Striatonigral (GABA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the Globus Pallidus

A

Input to both GABAergic projection neurones and output from both GABAergic
GPi is major output structure of BG
Striatum to GPi: post-synaptic D1 receptors in striatum; Substance P and Dynorphin cotransmitters released with GABA; direct pathway
Striatum to GPe: post-synaptic D2 receptors in striatum; Enkephalin released with GABA; indirect pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is the substantia nigra?

A

Made up of pars compacta (SNc) and pars reticulata (SNr)
Some don’t consider part of BG
SNc: pigmented melanin containing cells; output to striatum (D) - 70% die before showing symptoms of PD
SNr: Input from SNc (D), input from STN (glut) and output to thalamus (GABA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Describe the direct pathway.

A

SNc released dopamine onto striatum at D1 receptors with an excitatory effect. Some glutamate also comes from cortex (excit).
GABAergic neurones in striatum with D1 receptors become more active and release GABA (inhibitory) and substance P onto GPi.
GPi inhibited more, activity decreases.
Less GABA released onto thalamus (less inhibition, thalamus more active).
Thalamus releases more Glutamate onto cortex and striatum.
More Glut released onto motor areas of cortex roughly translating to more movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe the indirect pathway.

A

SNc releases Dopamine onto striatum at D2 receptors and has inhibitory effect.
Less GABA released onto GPe.
GPe inhibited less, activity increases.
More GABA released onto STN, inhibited more.
Less Glutamate released onto GPi and decreases activity.
Less GABA released onto thalamus, increasing activity.
More glutamate is released onto cerebral cortex and striatum.

Normally indirect pathway prevents movement but addition of dopamine inhibits indirect pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Describe the combination of both pathways.

A

Without dopamine, GPi is normally inhibited by direct and excited by indirect.

Direct = GPi inhibited by GABA, releases less GABA onto thalamus so more movement.
Indirect = GPi excited by glutamate releases more GABA onto thalamus so less movement.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are bradykinesia, akinesia and dyskenesia?

A

Bradykinesia - slowness of voluntary movement /postural reflexes
Akinesia - lack of movement
Dyskinesia - abnormal involuntary movement
–> Hyperkinetic = chorea
–> Abnormal postures = dystonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Describe how death of SNC neurones cause motor symptoms of Parkinson’s Disease.

A

Death of SNc neurones which normally release D onto striatum.

Indirect pathway isn’t being inhibited as much so more GABA onto Gpe.
GPe inhibited more, can’t release as much GABA onto STN.
STN less inhibited so more glutamate released onto GPi, making it more active.
More GABA released onto Thalamus, inhibiting it even more so less Glutamate released onto cortex, less movement or inability to initiate the movement.

Direct Pathway - less D so neurones aren’t activated as much.
Less GABA released onto GPi so inhibited less.
GPi releases more GABA onto thalamus, inhibiting it more
Less Glutamate onto cortex from thalamus

Overall GPi is being excited more by IP and inhibites less by DP so has loads of activity

36
Q

Describe the BG circuitry in the early stages of Huntington’s Disease.

A

Still not fully understood fully why but medium spiny neurones with D2 receptors (which release GABA and Enkephalin) in striatum are more susceptible so lose IP at beginning.

Less inhibition of GPe so more GABA released onto STN, inhibited it more.
Less Glutamate released onto GPi, activating it less than normal.
GPi releases less GABA onto thalamus, inhibiting it less.
More glutamate released onto cortex, more movement (chorea)

DP isn’t effected in early stages

37
Q

Describe the BG circuitry in the late stages of Huntington’s Disease.

A

Entire caudate and putamen degenerates, really big ventricles, impossible to generate movement.

Loss of DP
Less GABA released onto GPi, inhibiting it less
GPi releases more GABA onto thalamus, inhibiting it a lot more.
Thalamus releases a lot less Glutamate onto cortex, no movement generated

38
Q

What is the limbic system?

A

Anatomically connected cortical and subcortical structures that collectively play role in the way we experience and respond to emotional, social and motivational stimuli as well as learning and memory.

Dysfunction plays role in many disorders including anxiety, depression, addiction, psychosis, dementia

39
Q

What are the 3 components of an emotional state?

A

Autonomic = increased HR or sweating (hypothalamus)
Subjective feelings = unconscious (amygdala, cingulate gyrus)
Cognition = conscious thoughts about experience (cortex)

40
Q

What are the Subcortical structures of the limbic system?

A

Amygala - most anterior, below thalamus, close contact with hippocampus below it, strong emotions
Stria terminalis - white matter structure, posterior motion before S/A, projects to hypothalamus and nucleus accumbens
Hypothalamus - collection of nuclei in area of 3rd ventricle; ANS regulation, aggression, endocrine functions
Septal nuclei - regulates hypothalamus in context of aggression
Olfactory bulbs - inferior to frontal lobe, giant in rodents
Hippocampus - frontal lobe, types of memory
Thalamus (anterior)

41
Q

What are the cortical structures of the limbic system?

A

Cingulate gyrus - cognitive, attentional and emotional processing; between cingulate sulcus and corpus callosum
Parahippocampal gyrus - cortex surrounding hippocampus, underneath/medial, memory, quite big
Orbitofrontal cortex - above eyes in skull
Insular cortices - folded inside and looks like cortex under cortex of brain
Sensory association cortices

42
Q

Describe the theories behind limbic system emergence.

A

James Lange theory (1884) - physiological status of body triggers conscious experience of emotion (has to have physical stimulus).

Cannon bard theory - physiological state and emotional experience occuring simultaneously; proposed fight or flight
Removed entire cortex of cats and were angered very easily (cortex may regulated emotions a little bit but mostly elsewhere)

43
Q

Describe experiments with the septal nuclei.

A

Removed anything in virus that would cause infection and filled with channel rhodopsin-2 receptor fused to enhanced yellow fluorescent protein (CHR2-EYFP)
Injected into septal nuclei of rodents with a source of light.
CHR2 receptor will depolarise cells when activated.
Light stimulation stopped attacks by inhibiting hypothalamus that causes aggression

Under normal conditions, septal nuclei excite hypothalamus

44
Q

Describe the Papez circuit.

A

Proposed mechanism of emotion (1937)
Injected rabies virus into rabbits’ brain (acts as a tracer)
Cingulate gyrus receives stimuli from sensory association cortex
Projects to parahippocampal gyrus and hippocampus processes information
Information fed back to cingulate via mammillary bodies and anterior nucleus of thalamus

45
Q

What is Kluver-Bucy syndrome?

A

Discovered by removing temporal lobe of monkeys which survived and seemed to have normal behaviour except for lack of fear and being hypersexual.
Primary cause is herpes viral encephalitis.
Caused by removal of temporal lobes

46
Q

How did Paul Mclean (1950s) alter the Papez circuit?

A

Recognised importance of orbitofrontal cortex (info from hypothalamus), amygdala (info from parahippocampal gyrus and to hypothalamus) and nucleus accumbens

47
Q

Describe experiments involving the Amygdala

A

Urbach-Wiethe disease - calcification of amygdala, unable to recognise fearful faces

Fear conditioning (e.g. little albert) highlighted importance of amygdala with respect to learning to fear stimuli.

Joseph LeDoux (1994):
Played sound in loud chamber (BP goes up and rodent freezes)
Loud sound and foot shock (BP and freezing goes up a lot)
Eventually just sound causes responses like one with the shock

48
Q

What is the mesolimbic reward system?

A

Dopaminergic neurones in midbrain project to amygdala, orbitofrontal cortex and nucleus accumbens
Dopamine mediates pleasurable aspects of reward
System plays a role in addiction

49
Q

What are the types of memory associated with the hippocampus?

A

Declarative/explicit: Semantic (facts) and Episodic (personal experience)
Nondeclarative/implicit: Conditioning, Procedural, skills, habits

50
Q

What is the structure of the hippocampus?

A

Composed of dentate gyrus (smaller than CA), subiculum and Cornu Ammonis (CA)
CA and DG look like interconnected hooks
CA has three layers: (outside) Polymorphic, pyramidal, molecular (in)
DG has three layers: (outside) Polymorphic, Granular, Molecular (in)
Subiculum = transition to standard 6 layered entorhinal cortex

51
Q

Describe what is meant by long term potentiation in the hippocampus.

A

Cellular basis by which memories are stored (Bliss and Lomo, 1973).
Electrodes into entorhinal cortex and recorded postsynaptic responses in CA1
Stimulation of perforant pathway (close to DG) resulting in strengthening of synaptic connections in distant CA1 region.

DG to CA3 through mossy fibres.
CA3 to CA1 by Schaffer collaterals

Demonstrated brain’s ability to undergo lasting change in response to stimulation.
Suggested to be a cellular model by which memories are formed.

52
Q

What are place cells and what is their role in spatial memory?

A

Cells that fire depending on the location of the organism in the environment.
Use cues in room to navigate around the room and find the food.
Different cells in hippocampus seemed to fire when the rats were in different locations in the maze.
Additional evidence that hippocampus plays a role in cognitive maps came from lesion studies - rats could find platform quickly in water bath in control condition and with cortical removal but struggled with a hippocampal lesion.

53
Q

Describe hippocampal neurogenesis.

A

Occurs in sub-granular zone of the DG.
Quiescent undifferentiated stem cells (nestin, Sox-2, GFAP) activate and give rise to fast proliferating cells (nestin, sox-2).
Neuroblasts (doublecortin) reflect the commitment towards neuronal lineage.
Immature neurons begin to mature and extend dendrites into the molecular layer, and the axons project to the CA3 region

1980’s:
Discovery of Bromodeoxyuridine (BRDU) - thymidine analogue can be injected into rats and incorporated into DNA of newly forming cells

54
Q

What is the function of the hypothalamus?

A

Maintains homeostasis of several physiological processes.
Monitors physiological set points throughout the body and integrates autonomic responses with endocrine functions

55
Q

What are the hypothalamic zones?

A

Three zones with 11 nuclei
Periventricular (vertical surrounding third ventricle)
Medial close to 3rd ventricle
Lateral on outsides

56
Q

Which nuclei control which processes?

A

Paraventricular and Supraoptic - BP, water balance and electrolyte composition
Preoptic - Temperature/thermoregulation
Supra-chiasmatic - Circadian
Arcuate, Ventromedial, Lateral and Dorsomedial - Energy and Metabolism

57
Q

How is temperature controlled?

A

Preoptic nucleus regulates temperature via ANS

Release heat (parasympathetic) by cutaneous vasodilation and sweating.
Generate heat (sympathetic) by cutaneous vasoconstriction, brown fat thermogenesis and shivering.

58
Q

Describe how energy and metabolism is controlled.

A

Arcuate nucleus integrates gastro-intestinal, circulatory and autonomic signals from the bloodstream because it is in an area of the brain with a very thin BBB.

Hunger - Low blood glucose and insulin, hormone ghrelin and 1st order neuropeptide Y and agouti-related peptide expressing neurones
Ghrelin released from GI tract into blood, cycles and makes us hungry around mealtimes

Satiety - High blood glucose and insulin, hormone leptin and 1st order pro-opiomelanocortin and cocaine and amphetamine transcript expressing neurones.
Leptin released from adipose tissue and should make us feel less hungry

Mechanoreceptors in GI tract project to brain stem and tell Vagus nerve that stomach is stretching, getting too full and need to stop eating - Vagus nerve synapses in brain stem and other nerves go to arcuate nucleus

59
Q

How is blood pressure regulated?

A

Paraventricular and supraoptic nuclei regulated BP, water balance and electrolyte composition.
Stimulate pituitary gland to release Vasopressin which causes vasoconstriction and promotes water-reabsorption in kidneys.
Vagus nerve and brain stem signal hypotension to the paraventricular and supraoptic nuclei

Osmolarity of blood is detected by organum of vasculosum laminae terminalise and subfornical organs in hypothalamus

60
Q

Describe the ancestral visual system.

A

Regulates unconscious visual responses
Photoreceptors in retinal ganglion cells capable of light detection
Projections to superior colliculus assist head movement (tectospinal tract).
Projections to pretectal nuclei regulate parasympathetic component of oculomotor nerve (pupil constriction - cranial nerve 3)

Suprachiasmatic nucleus contains biological clock - lesioning halts cyclic rhythmicity
- Inject horseradish peroxidase into mice retina (acts as a tracer)
- Nucleus lights up on scan showing retina is connected
- HR and temp normally go up and down rhythmically during the day
- Rod less and coneless transgenic mice can still phase shift circadian rhythms to light so doesn’t need those

61
Q

Describe the primary visual system.

A

Rods and Cones > Optic Nerve (CN2) > Lateral Geniculate Nucleus > Primary visual cortex (Brodmann’s area 17)
Optic nerves cross over at optic chiasm to rearrange visual information then becomes optic tract once fully inside the brain.
Information first stops at lateral geniculate nucleus
Axons spread out (optic radiation) and go to PVC
Conscious visual perception
Colour produced through activation of rhodopsin pigments in cones

Two processing streams:
- Ventral (what) - inferior temporal lobe, object recognition, memory
- Dorsal (where or how) - posterior parietal lobe, object location, object positioning

62
Q

What is the input, output and function of the mammillary bodies?

A

Input from hippocampus via fornix
Output to anterior nucleus of thalamus, cingulate.
Function: episodic, implicit and spatial memory

63
Q

What does the brain stem consist of?

A

Midbrain, pons and medulla oblongata

64
Q

What is the tectospinal tract?

A

Originated in superior colliculus of midbrain.
Receives input from visual cortex and retina.
Decussates quickly and descends medially, synapsing in upper cervical levels of the SC.
Assists in head and neck orientation to visual stimuli.

65
Q

What is the location and function of Cranial Nerve I (Olfactory)?

A

Bottom of frontal lobe (easily visible)
Large nerves embedded in little channels
Sensory nerve
Associated with sense of smell

66
Q

What is the location and function of Cranial Nerve II (Optic)?

A

Merge into Optic Chiasm which has obvious X shape
Good landmark for mammillary bodies
Sensory nerves
Bringing information about vision to brain via primary visual system

67
Q

What is the location and function of Cranial Nerve III (Oculomotor)?

A

Emerges from junction between pons and midbrain
Associated with Oculomotor nuclei

Motor - regulates 4/6 muscles that move the eye (superior/inferior/medial/inferior oblique rectus muscle - up/down/to midline/away from midline)
Parasympathetic - Constricting pupils in response to light (might have persistent dilation of pupil if damaged)

68
Q

What is the location and function of Cranial Nerve IV (Trochlear)?

A

Only nerve that comes off dorsal side of brainstem
Smallest of all cranial nerves (spaghetti)
Associated with Trochlear Nuclei

Motor nerve
Innervates superior oblique rectus muscle in eye (depresses and rotates inwards)

69
Q

What is the location and function of Cranial Nerve V (Trigeminal)?

A

Arises from side of pons
Easy to identify - stump/thick

Sensory - Brings information from face
Nuclei are Mesencephalic Trigemeninal and Spinal Trigeminal

Motor - Controls muscles of mastication (anything requiring movement of the jaw)
Associated with Trigeminal nuclei

70
Q

What is the location and function of Cranial Nerve VI (Abducens)?

A

Arises from junction between pons and medulla
Motor nerve
Regulates lateral rectus muscle in eye (active when moving eye away from midline)
Associated with Abducens nuclei

71
Q

What is the location and function of Cranial Nerve VII (Facial)?

A

Arises from junction between pons and medulla
Part of pair 1 - more anterior

Motor - Controls all muscles of face
Associated with facial motor nuclei
Sensory - Brings sense of taste from anterior 2/3 of tongue
Associated with solitary and spinal trigeminal nuclei
Parasympathetic - Involved in salivation
Associated with salivatory nuclei

72
Q

What is the location and function of Cranial Nerve VIII (Vestibulocochlear)?

A

Arise from junction between pons and medulla
Pair 1 - More posterior

Sensory nerve
Auditory and balance information to inner ear then brain
Associated with Vestibular and cochlear nuclei

73
Q

What is the location and function of Cranial Nerve IX (Glosso-pharyngeal)?

A

Pair 2 - More Superior
Originates from side of medulla

Sensory - Information about taste from posterior 1/3 of tongue
Associated with solitary and spinal trigeminal nuclei
Motor - Regulates muscles controlling pharynx (probably get exaggerated gag reflex if damaged)
Associated with nucleus ambiguus
Parasympathetic - Involved in salivation
Associated with salivatory nuclei

74
Q

What is the location and function of Cranial Nerve X (Vagus)?

A

Originates from side of medulla
Pair 2 - More inferior

Sensory - Brings information from some of the muscles in neck (pharynx and larynx)
Associated with Solitary and spinal trigeminal nuclei
Motor - Innervates soft palette, pharynx and other muscles in the neck
Associated with nucleus ambiguus
Parasympathetic - Rest and digest (e.g. HR)
Associated with dorsal motor nuclei

75
Q

What is the location and function of Cranial Nerve XI (Spinal Accessory)?

A

Located most inferiorly
Difficult to see

Motor nerve
Innervates trapezius and sternocleidomastoid muscles which control head rotation from side to side
Associated with accessory nuclei

76
Q

What is the location and function of Cranial Nerve XII (Hypoglossal)?

A

Emerges between junction between medulla and olive (lateral side of medulla)

Motor nerve
Innervates muscles of the tongue
Associated with Hypoglossal nuclei

77
Q

What is the function of the cerebellum?

A

Assists with equilibrium, posture and dynamic coordination and synchronisation of muscles
Communicates accuracy of movement back to the cortex

Injury can result in ataxia
May include postural and gait disturbance or decomposition of movements due less precise, uncontrolled and incorrectly timed movements

78
Q

What is the structure of the cerebellum?

A

10% of total brain volume but has half of the neurons in the entire brain
Tightly folded thin layer of cortex with white matter below
4th ventricle is space between cerebellum and brain stem

Anterior Lobe (smallish)
Primary Fissure
Posterior Lobe (Largest)
Posterolateral fissure
Flocculonodular Lobe (Composed of nodule and flocculi, not visible until you cut it up, tucked right against brainstem)

Vermis = depression directly down midline

Cerebellar peduncles attach the cerebellum to the brain stem:
Superior to midbrain
Middle to pons
Inferior to medulla oblongata

79
Q

What is the structure of the cerebellar cortex?

A

3 Layers:
Granular (inner) - numerous granular cells that receive input
Purkinje (middle) - single layer of cells, output to cerebellar nuclei
Molecular (outer) - few interneurons, Purkinhje dendrites, granular axons

Mossy Fibres:
- Originate in spinal cord and brain stem nuclei
- Each one innervates hundreds of granular cells
- Granular axons ascend, send out parallel fibres (molecular) and synapse with Purkinje cells

Climbing Fibres:
- Originate in the olives
- Axons climb and wrap around Purkinje cell bodies and dendrites
- Each Purkinje cell receives input from one climbing fibre

80
Q

What are the 3 functional pathways in the cerebellum?

A

Spinocerebellum (vermis and intermediate zones)
Cerebrocerebellum (Lateral hemispheres)
Vestibulocerebellum (Flocculonodular lobe)

81
Q

Describe the vestibulocerebellum pathway.

A

Mediates posture, balance, some reflexes

Vestibulocochlear nerve brings sound and balance information into the pons where it synapses with the Vestibulocochlear nucleus. Series of Vestibulocerebellar fibres go through the inferior cerebellar peduncle into cerebellum and synapse at granular cells of Flocculonodular lobe. Synapse with Purkinje cells. Output to Fastigial Nucleus. Fastigial fibres go out through inferior cerebellar peduncle where they make connections with the vestibulocochlear nuclei and reticular formation

82
Q

What is the Vestibulospinal tract?

A

Originates in vestibulocochlear nuclei
Medial: Synapses in cervical SC with muscles that maintain head and neck position; bilateral
Lateral: Synapses in many levels of SC (Cervical, thoracic, sacral) with muscles that help maintain balance and posture via extensor and anti-gravity muscles

83
Q

What is the reticular formation and reticulospinal tract?

A

Ill-defined group of inter-mingled neurons that spain the brain stem and involve a variety of neurotransmitters
Medial (Raphe - Serotonin), Medial (Magnocellular) and Lateral (Parvocellular)

Tract:
- Originates in pontine and medullary reticular formation
- Medial/Lateral: between pyramids of medulla; synapses throughout spinal cord with muscles
- Assists vestibulospinal tract with controlling extensor muscles

84
Q

Describe the cerebrocerebellum pathway.

A

Helps with planning and timing of movements.

Corticopontine fibres initiate in the cortex and make their way through the internal capsule and midbrain before reaching the pons where they synapse in the pontine nucleus. Decussates to the other side of the body. Pontocerebellar fibres make their way through the middle cerebellar peduncle to granular cells in the lateral hemispheres of the cerebellum. Purkinje fibres to dentate nucleus. Dentatorubrothalamic fibres synapse in thalamus which continues to cortex and other fibres synapse in red nucleus (initiation point for rubrospinal tract).

85
Q

What is the rubrospinal tract?

A

Originates in red nucleus of midbrain
Decussates quickly and descends laterally with corticospinal tract.
Receives collaterals from corticospinal tract and provides it with assistance
Flexor adjustments primarily of the upper limbs
Some communication with corticospinal tract and able to compensate if there is damage

86
Q

Describe the spinocerebellum pathway.

A

Sensory neurones synapse in SC; spinocerebellar tracts (mossy fibres)
The Dorsal spinocerebellar tract goes through the inferior cerebellar peduncles (sensory).
The Ventral spinocerebellar tract goes through the superior cerebellar peduncles (motor).
Both arrive in granulae cells of vermis and intermediate zones in the cerebellum. Purkinje cells project to interposed nuclei. Interposition-rubrothalamic fibres (some make connection with red nucleus and rubrospinal tract; others go to thalamus where final thalamocortical fibres take information to the cortex)

Building Brains (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions