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S2.3 Neurology > Physiology > Flashcards

Physiology Flashcards

1
Q

What are the different types of glia in the CNS and PNS?

A

CNS

  • Astrocytes
  • Oligodendrocytes
  • Microglia
  • Ependymal cells

PNS

  • Satellite cells
  • Schwann cells
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2
Q

What is CNI, what does it innervate, where does it pass through skull?

A

Olfactory nerve
Special sensory - smell
Passes through cribriform plate of ethmoid bone

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3
Q

What is CNII, what does it innervate, where does it pass through skull?

A

Optic nerve

Special sensory - vision
Passes through optic canal

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4
Q

What is CNIII, where does it emerge, where does it pass through skull, what does it innervate?

A

Oculomotor nerve
Emerges from midbrain
Somatic motor (extraocular muscles and eyelid muscles)
Visceral motor - parasympathetic for pupil constriction and to ciliary muscle causing lens accommodation
Passes through superior orbital fissure

Muscles

  • recti (superior, medial, inferior)
  • inferior oblique
  • levator lapebrae superioris (eyelid)
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5
Q

What is CNIV, where does it emerge, where does it pass through skull, what does it innervate?

A

Trochlear nerve
Emerges from dorsal surface of midbrain
Somatic motor of superior oblique
Passes through superior orbital fissure

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6
Q

What is CNV, where does it emerge, where does it pass through skull, what does it innervate?

A 
Trigeminal
Emerges from pons, travels through trigeminal ganglion
- V1 exits via superior orbital fissure
- V2 exits via foramen rotundum
- V3 exits via foramen ovale

V1 - general sensory - forehead, scalp, eyelids, nose
V2 - general sensory - face over maxilla, maxillary teeth, TMJ, palate
V3 - general sensory - face over mandible, mandibular teeth, TMJ, mouth mucosa, anterior 2/3rds of tongue
- somatic motor - muscles of mastication, part of digastric

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7
Q

What is CNVI, where does it emerge, where does it pass through skull, what does it innervate?

A

Abducens nerve
Emerges between pons/medulla
Exits via superior orbital fissure

Somatic motor - extraocular muscle (lateral rectus)

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8
Q

What is CNVII, where does it emerge, where does it pass through skull, what does it innervate?

A

Facial nerve
Emerges from pons and medulla
Exits via internal acoustic meatus/stylomastoid foramen

Various components

  • somatic motor - facial expression, stapedius, part of digastric
  • visceral motor - parasympathetic innervation of submandibular/sublingual salivary glands, lacrimal glands, nose/palate glands
  • general sensory - external acoustic meatus
  • special sense - taste from anterior 2/3rds of tongue/palate
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9
Q

What is CNVIII, where does it emerge, where does it pass through skull, what does it innervate?

A

Vestibulocochlear nerve
Emerges between pons and medulla and exits via internal acoustic meatus, divides into vestibular and cochlear nerves

Special sensory - vestibular sensation and hearing

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10
Q

What is CNIX, where does it emerge, where does it pass through skull, what does it innervate?

A

Glossopharyngeal nerve
Emerges from medulla
Exits via jugular foramen

Various components

  • special sensory - taste from posterior 1/3rd of tongue
  • general sensory - cutaneous sensation from middle ear, posterior oral cavity
  • visceral sensory - sensation from carotid body and sinus
  • somatic motor - to stylopharyngeus
  • visceral motor - parasympathetic to parotid gland
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11
Q

What is CNX, where does it emerge, where does it pass through skull, what does it innervate?

A

Vagus
Emerges from medulla
Exits via jugular foramen

Various components

  • special sensory - taste from epiglottis and palate
  • general sensory - sensation from auricle, external acoustic meatus
  • visceral sensory - pharynx, larynx, trachea, bronchi, heart, oesophagus, stomach, intestine
  • somatic motor - pharynx, larynx, palate, oesophagus
  • visceral motor - parasympathetic innervation in bronchi, gut, heart
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12
Q

What is CNXI, where does it emerge, where does it pass through skull, what does it innervate?

A

Accessory nerve
Small cranial (medulla) and large spinal roots
Exit via jugular foramen

Somatic motor - striated muscle of soft palate, pharynx, larynx, and to SCM and trapezius

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13
Q

What is CNXII, where does it emerge, where does it pass through skull, what does it innervate?

A

Hypoglossal nerve
Emerges from medulla
Exits through hypoglossal canal

Somatic - to muscles of tongue

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14
Q

What are the pyramidal tracts made up of? Where do they cross?

A

Corticospinal and corticobulbar tracts
- motor fibres

Lateral Corticospinal fibres (90% of all CST fibres) decussate in pyramids
Anterior decussate (10% of CST fibres) at spinal level

Corticobulbar tract supply contralateral cranial nerves

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15
Q

Where do motor neurons have their cell bodies?

A

Ventral horn

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16
Q

What information travels up the lateral spinothalamic tracts?

A

Pain and temperature from contralateral side

  • crosses at level of entry (or close to)
  • travels through VPL nucleus of thalamus, to post central gyrus in parietal lobe
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17
Q

What information travels up the dorsal column of the spinal cord?

A

Fine touch
Tactile localisation
Vibration sense
Proprioception

Of ipsilateral side

  • crosses at medulla (gracile and cuneate nuclei)
  • travels up through medial lemniscus in pons, VPL nucleus in thalamus, to post central gyrus in parietal lobe
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18
Q

What is Brow-Sequard syndrome?

A

Hemisectional damage to spinal cord

  • ipsilateral loss of touch, vibration, proprioception
  • contralateral loss of pain, temperature
  • contralateral (spastic) paralysis
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19
Q

How many neurons are in a single ascending pathway, and a single descending pathway?

A

3 neurons in ascending pathways

  • neuron to DRG
  • DRG to synapse in dorsal horn of SC
  • dorsal horn to thalamus (after crossing over)

2 neurons in descending pathway

  • UMN (cortex to ventral horn)
  • LMN (ventral horn to motor unit)
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20
Q

What is the frontal lobe of the brain responsible for?

A

Primary Motor cortex - precentral gyrus
Inferior frontal gyrus - Broca’s area
Prefrontal cortex - cognitive functions of higher-order, judgement, prediction, planning

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21
Q

What is the parietal lobe responsible for?

A

Primary sensory cortex - postcentral gyrus
Superior parietal lobule - interpretation of general sensory information
Inferior parietal lobule - interface between PSC and visual/auditory areas (in dominant hemisphere)

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22
Q

What is the temporal lobe responsible for?

A

Superior temporal gyrus - primary auditory cortex
Auditory association areas - Wernicke’s in dominant hemisphere - auditory understanding
Inferior surface - receives fibres from olfactory tract

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23
Q

What is the occipital lobe responsible for?

A

Medial surface of lobe - primary visual cortex

Rest of lobe is visual association cortex - image interpretation

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24
Q

What areas make up the limbic system?

A 
Cingulate gyrus
Hippocampus
Parahippocampal gyrus
Amygdala
Others
25
Q

What are the different types of white matter fibres?

A

Commissural fibres - connect corresponding areas of each hemisphere
Association fibres - connect cortex areas to cortex areas
Projection fibres - run between cortex and various subcortical centres - pass through coronal radiata and internal capsule

26
Q

What make up the functional basal ganglia?

A 
Caudate nucleus
Putamen (half of lentiform nucleus)
Globus pallidus (other half)
Substantia nigra
Nucleus accumbens + olfactory tubercle
Subthalamic nucleus
27
Q

What are the input and output areas of the basal ganglia?

A

Caudate and putamen are input regions (from motor/premotor areas, thalamus)
They connect to globus pallidus and substantia nigra
Globus pallidus projects to thalamus which then sends fibres to motor cortex

‘Extrapyramidal system’

28
Q

What four systems control movement?

A

Descending control pathways
Basal ganglia
Cerebellum
Local spinal cord/brain stem circuits

29
Q

What kind of paralysis will occur in LMN lesions vs UMN lesions?

A

LMN - flaccid paralysis
UMN - spastic paralysis (posture regulating pathways)

Weakness rather than paralysis in corticospinal lesions

30
Q

What happens in excessive load of muscles?

A

GTO reflex activated - muscle relaxes to prevent damage

- can be overridden

31
Q

What are the otolith organs?

A

Utricle and saccule

  • detect linear acceleration
  • back/front tilt detected by utricle
  • vertical tilt detected by saccule

(Rotational acceleration by semicircular canals)

32
Q

What are the sensory receptors in the semicircular canals, where are they located?

A

In the swellings at the base of the canals (ampullae), sensory receptors called cristae contain flexible gelatinous structure called cupula, responds to movements of endolymph

Embedded within gelatinous cupula are cilia of hair cells which synapse with CNVIII directly

33
Q

What are the sensory receptors of the otolith organs?

A

Collectively known as the maculae
Utricle’s are orientated on horizontal plane
Saccule on vertical

34
Q

What are the different vestibular reflexes?

A

Tonic labyrinthine reflex - keep axis of head in constant relationship with rest of body (maculae and neck receptors)

Dynamic righting reflex - rapid postural adjustments to prevent falling when you trip - involves extension of all limbs

Vestibulo-ocular reflex - eyes helping with proprioception/balance

  • static reflex - eyes intort/extort/move to maintain image when head is being tilted
  • nystagmus when fails
35
Q

How can nystagmus be used to test vestibular function?

A

Post-rotatory nystagmus
- subjects rotated in chair, get left nystagmus when accelerating to left, then right nystagmus on deceleration

Caloric stimulation

  • water which creates convection currents within endolymph, stimulating receptors
  • warm fluid causes nystagmus towards affected side, cold causes nystagmus away
36
Q

What (broad) groups of spinal cord tracts do what in terms of motor function?

A

Lateral pathways control voluntary movements of distal muscles (cortical control)
Ventromedial pathways control posture and locomotion (brain stem control)

37
Q

What two ventromedial pathways control posture/locomotion?

A

Vestibulospinal and tectospinal tract

38
Q

What spinal tracts control trunk/antigravity muscles?

A

Pontine and medullary reticulospinal tract

39
Q

What are some disorders affecting the basal ganglia?

A

Parkinsons - substantia nigra degeneration

Huntington’s - profound loss of caudate, putamen, globus pallidus

40
Q

What is the suprachiasmatic nuclei’s relevance to sleep?

A

The SCN (hypothalamus) demonstrates ~24hr circadian rhythm
Electrical stimulation of the SCN can promote sleep and damage can disrupt the sleep/wake cycle
Activity in SCN stimulates release of melatonin from pineal gland.

41
Q

How does EEG vary in wakefulness vs sleep?

A

Relaxed Awake - high frequency high amplitude (alpha waves)
Alert Awake - higher frequency, lower amplitude asynchronous waves (beta waves)

Children, stress/frustration - low frequency waves, high variety amplitude (theta waves)

Deep sleep - low frequency, high amplitude (delta waves)

42
Q

What are the stages of sleep?

A

Stage 1 - slow wave, non-REM, s-sleep
- light sleep, slow eye movements, theta waves

Stage 2 - slower frequency but bursts of rapid waves (sleep spindles), eye movements stop

Stage 3 - very low frequency, high amplitude (delta waves) interspersed with episodes of faster waves

Stage 4 - Exclusively delta waves
(stage 3 and 4 = deep sleep)

REM sleep - rapid eye movements

43
Q

What physiological processes does sleep support?

A 
Neuronal plasticity
Learning and memory
Cognition
Clearance of CNS waste
Conservation of energy
Immune function
44
Q

What are the various types of sleep disorder?

A

Insomnia

  • chronic/primary
  • temporary/secondary

Nightmares - REM sleep

Night terrors - delta sleep (common in 3-8yo)
- trash/scream, eyes may be open but fail to recognise parents, can’t remember when awake

Somnambulism - nonREM sleep (mainly stage 4)
- sleep walking

Narcolepsy - patients entire directly into REM sleep
- linked to dysfunctional orexin release from hypothalamus

45
Q

What are the 3 main components (and their anatomical areas) in memory?

A

Formation of memory - hippocampus
Storage of memory - cortex
Accessing of memory - thalamus

46
Q

Damage to the hippocampus will result in what?

A

Anterograde amnesia

  • sensory memory and previous LTMs intact
  • can’t form new LTMs
47
Q

Damage to the thalumus without damage to the hippocampus will result in what (with respect to memory)?

A

Retrograde amnesia

- suggests thalamus is required for searching existing memories

48
Q

What changes occur at a synaptic level for LTM?

A

Increase in neurotransmitter release sites on presynaptic membrane
Increase in number of neurotransmitter vesicles stored and released
Increase in number of presynaptic terminals

49
Q

What are the different types of LTM?

A

Declarative/explicit
- abstract memory for events (episodic memory) and for words/rules/language (semantic memory) - relies heavily on hippocampus

Procedural/Reflexive/Implicit
- acquired through repetition. Includes motor memory. Based mainly in in the cerebellum and independent of hippocampus.

50
Q

What is the Papez circuit?

A

Hippocampus > Mamillary bodies > anterior thalamus > cingulate gyrus > hippocampus (repeat)

Reverberation through here and frontal cortex/sensory and association areas for consolidation

51
Q

What vitamin is deficient in Korsakoff’s?

A

Vitamin B1 - leading to limbic system damage

52
Q

What are the different types of primary afferent fibres?

A

Aalpha - proprioception - large myelinated
Abeta - proprioception, cutaneous sensation (touch, pressure, vibration) - large myelinated
Adelta - cutaneous sensation (cold, ‘fast’ pain, pressure) - small myelinated
C - cutaneous sensation (warmth, ‘slow’ pain) - unmyelinated

Aalpha/beta travel up dorsal column (ipsilateral), decussate in brainstem
Adelta/C (nociceptors) travel anterolateral tracts (contralateral spinothalamic), decussating in spinal cord

53
Q

What are the areas involved in pain pathways?

A

Afferents travel up spinal cord to thalamus, which projects to cingulate cortex, somatosensory cortex, limbic system

Limbic system projects to PAG, RVM and down.

54
Q

What is the difference between allodynia and hyperalgaesia?

A

Allodynia - decreased threshold for response

Hyperalgaesia - exaggerated response to normal and supranormal stimuli

55
Q

What is the difference between nociceptive pain and neuropathic pain?

A

Nociceptive pain - sensory experience that occurs when sensory neurons respond to noxious stimuli
Neuropathic pain - pain initiated or caused by a primary lesion or dysfunction in the somatosensory nervous system

56
Q

What analgaesics affect transduction?

A

NSAIDs
Ice
Rest
Local Anaesthetics

57
Q

What analgaesics affect transmission?

A

Nerve blocks
Opioids
Anticonvulsants
Surgery (DREZ, cordotomy)

58
Q

What analgaesics affect perception?

A 
Education
CBT
Distraction
Relaxation
Graded motor imagery
Mirror box therapy
59
Q

What analgaesics affect descending modulation?

A

Placebos
Opioids
Antidepressants
Spinal cord stimulation

S2.3 Neurology (18 decks)

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