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Medicine > Neuro summary > Flashcards

Neuro summary Flashcards

1
Q

What are the cellular components of the nervous system

A

Neurones and glial cells

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2
Q

What are glial cells

A

Neurone supporting cell, maintains environment. Both CNS and PNS

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3
Q

What is the soma

A

Cell body

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4
Q

What is the Nissl substance

A

Granules containing rough ER and free ribsomes. Site of protein synthesis in neurones

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5
Q

Where are nissl granules found

A

Cell body/soma and dendrites

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6
Q

Where is the axon potential initiated from

A

Axon hillock. The axon hillock has fast voltage gated sodium channels, the dendrites don’t

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7
Q

What is the myelinating cell of CNS vs PNS

A

CNS = Oligodendrocytes
PNS = Schwann cells

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8
Q

What is a key difference between oligodendrocytes and schwann cells

A

Oligodendrocytes can myelinate many axonal segments, schwann cells only 1

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9
Q

What is the most numerous glial cell

A

Oligodendrocytes

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10
Q

What are the functions of astrocytes

A

1) Storage of glycogen/lactate for neurones. Neurones do not store
2) Uptake of excess ions + neurotransmitters
3) Modulation of transmission. Release ATP which is converted to adenosine
4) Astrocyte end feet modulate blood flow

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11
Q

What is adenosines function in the brain

A

Inhibitory neurotransmitter. Promotes sleep + supresses arousal

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12
Q

What are gliotransmitters

A

Substances released from glial cells eg ATP from astrocytes which regulate neuronal synaptic transmission

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13
Q

What is the origin of most glial cells

A

All are ectodermal in origin apart from microglia which are mesodermal

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14
Q

What is the function of the microglia

A

Immune cells of the brain. Initiate phagocytosis + act as antigen presenting cells

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15
Q

What is the function of ependymal cells

A

Produce CSF in choroid plexus. Have cilia to facilitate movement of CSF

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16
Q

What are the 4 anatomically defined neurones

A

Multipolar, Bipolar, pseudounipolar, unipolar

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17
Q

Where are multipolar neurones found

A

Brain and spinal cord (most common)

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18
Q

Where are bipolar neurones found

A

Ganglia of CNVIII
Retina
Olfactory epithelium

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19
Q

Where are pseudounipolar neurones found

A

Dorsal root ganglia
All CN ganglia apart from VIII

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20
Q

Where are unipolar neurones found

A

Not in vertebrates

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21
Q

Are cranial nerves peripheral or central?

A

Peripheral. Apart from the CN II Optic which is CNS. The optic nerve is ensheathed in all 3 meningeal layers

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22
Q

What connective tissue surrounds peripheral nerves

A

Epineurium, perineurium, edoneurium

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23
Q

What is ganglions

A

Collection of cell bodies

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24
Q

What does white matter contain

A

Myelinated axons

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25
Q

What does gray matter contain

A

Cell bodies, dendrites, neuroglia

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26
Q

What are the components of the blood brain barrier

A

1) Tight junctions between endothelial cells + basement membrane
2) Pericytes
3) Astrocyte end feet
4) Microglia

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27
Q

Where is CSF produced

A

Choroid plexus. Covers the 2 lateral ventricles, and the roof of the 3rd + 4th ventricles

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28
Q

How much CSF is produced/day

A

500ml

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29
Q

How much CSF is present in the body at any given time

A

150ml

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30
Q

How is CSF produced

A

Ependymal cells form the blood-cerebral spinal fluid barrier. They secrete CSF

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31
Q

What is the osmolarity between CSF and blood

A

Have the same osmolarity

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32
Q

Where is CSF found

A

The ventricles, the subarachnoid space (between arachnoid mater and pia mater) and spinal canal

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33
Q

What do arachnoid granulations/villi do

A

Protrusions of arachnoid mater into the dura mater. Allow CSF to drain into the dural venous sinuses

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34
Q

What are the functions of CSF

A

1) Buoyancy
2) Protection
3) Homeostasis
4) Clearing waste

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35
Q

What is hydrocephalus

A

Abnormal increase of the volume of CSF within the ventricular system. Causes increased pressure

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36
Q

What are the 3 types of neurotransmitters based on function

A

Excitatory, inhibatory, neuromodulators

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37
Q

What do neuromodulators do

A

They alter the strength of the transmission between neurones by affecting the amount of neurotransmitter released

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38
Q

What is the most abundant neurotransmitter in the brain

A

Glutamate, excitatory

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39
Q

What is the main importance of glutamate

A

involved in learning and memory

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40
Q

Is acetylcholine excitatory or inhibatory

A

Excitatory

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41
Q

Is GABA excitatory or inhibitory

A

Inhibatory

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42
Q

Is glycine excitatory or inhibitory

A

Inhibitory

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43
Q

What are the divisions of the autonomic nervous system

A

Sympathetic, parasympathetic, enteric

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44
Q

How many neurones make up the efferent (motor) limb of the autonomic nervous system

A

Generally 2. Preganglionic with a cell body in the CNS and post ganglionic with a cell body in the periphery

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45
Q

What neurotransmitters do the sympathetic vs parasympathetic nervous systems use

A

Sympathetic = acetylcholine, norepinepherine
Parasympathetic = acetylcholine, acetylcholine

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46
Q

What vertebrae do sympathetic neurones arise from

A

T1 - L2/3

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47
Q

What are the exceptions to the 2 neurone rule of the ANS

A

For sympathetic innervation of the chromaffin cells of the adrenal medulla, the preganglionic neurone synapses directly - 1 neurone. Acetylcholine is the neurotransmitter

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48
Q

What are the length differences of the 2 ANS neurones

A

Sympathetic = short, long
Parasympathetic = long, short

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49
Q

Do efferent fibres exit the spinal cord anteriorly or posteriorly

A

Anteriorly

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50
Q

Where are the cell bodies of sympathetic preganglionic neurones located

A

In the grey matter on the spinal cord

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51
Q

What does the white rami communicans do?

A

Carries preganglionic nerve fibres from the spinal cord to the sympathetic trunk

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52
Q

Are the sympathetic neurones ipsilateral or contralateral?

A

Ipsilateral, the fibres do not decussate

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53
Q

After the sympathetic preganglionic neurones emerge from T1-L2/3, they enter the sympathetic chain. What can happen then?

A

1) Ascend/descend the symp trunk then synapse with a symp postganglionic neurone
2) Synapse on that level with a symp post ganglionic neurone. Join the grey rami communicans, then a spinal nerve
3) Travel through the sympathetic chain without synapsing –> becomes a splanchnic nerve
4) Single preganglionic neurone to adrenal medulla

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54
Q

D) Paravertebral ganglia

A

Sympathetic chain. String of synapses adjacent to the spinal cord

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55
Q

What are the two main divisions of splanchnic nerves

A

1) Cardiopulmonary
2) Abdominopelvic

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56
Q

What receptor type does acetylcholine bind to

A

Cholingernic receptors –> usually muscarinic

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57
Q

What receptor type does norepinephrine bind to

A

Adrenergic receptors –> alpha 1,2 and beta 1,2,3

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58
Q

What is the sympathetic innervation of the head + neck

A

Cervical ganglia -
1) superior = head, arterial smooth m
2) middle = neck, arterial smooth m
3) inferior = heart, arterial smooth m

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59
Q

What is the enteric nervous system

A

(Arguably) division of the ANS which controls digestion

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60
Q

What are the two plexuses of the enteric nervous system

A
  • Myenteric (Auerbach’s)
  • Submucosal (Meissner’s)
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61
Q

What sets up the resting membrane potential

A

Na+/K+ ATPase pump

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62
Q

What is the resting membrane potential of neurones

A

-70 mV

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63
Q

What are the ion concentrations inside vs outside the neurone

A

Inside = K+ and organic ions
Outside = Na+ and Cl-

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64
Q

What ion has the greatest influence on resting membrane potential

A

K+

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65
Q

What is the Na+/K+ ATPase pump

A

Actively transports 3 sodium ions out and 2 potassium ions in against a concentration gradient

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66
Q

D) Equilibrium potential

A

The point at which the rate of ions leaving a cell down a concentration gradient is equal to the rate at which ions enter via an electrochemical gradient

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67
Q

What is the Nernst equation

A

The Nernst equation is used to calculate the value of the equilibrium potential for a particular cell for a particular ion

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68
Q

What is hyperkalaemia and what does this cause

A

High blood K+ level. Means that the diffusion of K + out of cells is reduced (less conc gradient). So the RMP is closer to the threshold for an action potential
–> neurones are more easily excitable

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69
Q

What is the refractory period

A

The period of time after an action potential when sodium channels close

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70
Q

What are the divisions of the refractory period

A
  • Absolute refractory period
  • Relative refractory period
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71
Q

D) Absolute refractory period

A

When the sodium channel are closed after an action potential and cannot be reopened, regardless of the strength of the stimulus

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72
Q

D) Relative refractory period

A

When the sodium channels begin to come out of inactivation. Another action potential can be generated, if the stimulus is strong enough

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73
Q

D) Local current

A

The diffusion of sodium ions in an axon down a concentration gradient. This diffusion depolarises the membrane at the next node so the threshold potential is reached and another action potential is generated

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74
Q

What factors dictate the distance of a local current at which the threshold is no longer reached

A

1) Membrane capacitance (ability to store charge - low is better)
2) Membrane resistance (number of open ion channels - low number so high resistance is better)
–> low cap, high mem

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75
Q

How does the myelin sheath increase the speed of conduction

A
  • Increases membrane resistance and decreases membrane capacitance
    –> saltatory conduction
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76
Q

What are the two main classes of receptors found on neurones

A

Metabotropic and inotropic

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77
Q

What is a metabotropic receptor

A

A membrane receptor which when activated uses secondary messengers to change the cells activity

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78
Q

What is an inotropic receptor

A

A ligand-gated ion channel

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79
Q

What is the Post synaptic potential

A

Change in the membrane potential of a post synaptic neurone as a result of excitatory/inhibitory neurotransmitters. If the post synaptic potential is great enough, the threshold will be reached and an action potential generated

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80
Q

Is the neurotransmitter dopamine excitatory or inhibitory

A

Both, it depends on which receptor it binds to

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81
Q

How do excitatory neurotransmitters eg glutamate work

A
  • Glutamate binds to an a receptor resulting in the opening on non-selective cation channels
  • Na+ enters, K+ leaves slowly. Na + will be more significant
  • The membrane potential increases
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82
Q

How do inhibitory neurotransmitters eg GABA work

A
  • GABA binds to receptors resulting in the opening chloride ion channels
  • Chloride ions enter the post synaptic neurone causing hyperpolarisation
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83
Q

What is spatial summation

A

Neurotransmitters are released from several presynaptic neurones at once

84
Q

What is temporal summation

A

A presynaptic neurone releases neurotransmitters within short time intervals

85
Q

What happens in an epileptic seizure

A

A sudden excess increase in electrical activity. Can be as a result of increased excitatory neurotransmitters or reduced inhibitory

86
Q

What is Guillain-Barre syndrome

A

Autoimmune damage to the myelin sheaths of the peripheral nerves resulting in rapid muscle weakness

87
Q

What is synaptic plasticity

A

The ability of synapses to change over time (become stronger/weaker or form/eliminate) in response to an increase or decrease in their activity
‘fire together wire together’

88
Q

D) Neuropeptides

A

Large neurotransmitters that are produced in the cell body and are then packaged into secretory granules and sent to the axon terminal

89
Q

What is the speed of response for inotropic vs metabotropic receptors

A

Fast for inotropic, slow for metabotropic

90
Q

How are neurotransmitters removed

A

1) Re uptake by presynaptic neurone
2) Breakdown by enzyme
3) Diffusion into surrounding area –> astrocytes

91
Q

D) Ascending pathways

A

the sensory pathways - both CNS and PNS

92
Q

D) Sensory transduction

A

The process of converting a sensory signal into an electrical signal

93
Q

What are the two main types of sensory receptors

A

Tonic and phasic receptors

94
Q

What do tonic receptors do

A

Slow adapting. They fire as long as the stimulus is present = info about the length of the stimulus

95
Q

What do phasic receptors do

A

Fast adapting. They stop firing upon continuous stimulation = quick info about changes to the stimulus

96
Q

D) Nociceptors

A

Receptors which respond to noxious stimuli, resulting in the sensation of pain

97
Q

What are examples of mechanoreceptors

A

Pacinian corpuscles (phasic), muscle spindles, golgi tendon organs

98
Q

Are cold or hot thermoreceptors more common

A

Cold

99
Q

Are thermoreceptors phasic or tonic

A

Initially phasic but then switch to tonic - adapting to environment

100
Q

What are the conscious ascending tracts

A

1) Dorsal column-medial lemniscal (DCML)
2) Anterior and lateral spinothalamic tracts

101
Q

What information does the DCML relay

A

Fine touch, vibration, proprioception, 2 point discrimination

102
Q

DCML: Where do signals from the upper limb (T6 and above) travel

A

Travel in the fasciculus cuneatus (lateral dorsal column), then synapse onto the nucleus cuneatus of the medulla

103
Q

DCML: Where do signals from the lower limbs (lower than T6) travel

A

Travel in the fasciculus gracilis (medial dorsal column), then synapse onto the nucleus gracilis of the medulla

104
Q

DCML: Where do second order neurones originate and end

A

In the cuneatus/gracilis nuclei of medulla, decussate go to the thalamus

105
Q

DCML: When do the DCML fibres decussate

A

The 2nd order neurones decussate in the medulla

106
Q

DCML: Where do the 3rd order neurones originate + end

A

They originate in the thalamus, travel through the internal capsule and terminate in the primary sensory cortex

107
Q

What information does the anterior spinothalamic tract relay

A

Crude touch and pressure

108
Q

What information does the lateral spinothalamic tract relay

A

Pain and temperature

109
Q

Spinothalamic tract: Where do 1st order neurones originate + end

A

They enter the spinal cord and synapse at the tip of the dorsal horn in the substantia gelatinosa

110
Q

Spinothalamic tract: Where do the fibres decussate

A

The 2nd order neurones decussate in the spinal cord a couple of vertebral levels above entry, to form the anterior and lateral spinothalamic tracts

111
Q

Spinothalamic tract: Where do the 2nd order neurones originate + end

A

Start in the substantia gelatinosa, decussate then go up to the thalamus

112
Q

What information do the spinocerebellar tracts relay

A

Unconscious proprioception, they help the brain to coordinate and refine movements

113
Q

What is the input to the spinocerebellar tracts

A

Muscle spindle, golgi tendon organ, joint capsule

114
Q

Where does the spinocerebellar tract end

A

Ipsilateral cerebellum

115
Q

Where do the conscious sensory tracts end

A

Contralateral primary sensory cortex

116
Q

Will damage to the DCML in the spinal cord cause an ipsilateral or contralateral loss of fine touch, proprioception etc

A

Ipsilateral as fibres decussate in the medulla

117
Q

Will damage to the Spinothalamic tract in the spinal cord cause an ipsilateral or contralateral loss of crude touch, pain etc

A

Contralateral as fibres decussate in the spinal cord

118
Q

What is Brown-Sequard syndrome

A

The hemi section of the spinal cord
= Ipsilateral DCML
= Contralateral spinothalamic
= Ipsilateral hemiparesis (descending)

119
Q

Will damage to the spinocerebellar tract cause ipsilateral or contralateral loss of muscle coordination

A

Ipsilateral. Usually there is also descending motor tract damage which will be more ‘relevant’

120
Q

D) Descending tract

A

Neural pathways by which motor signals are transmitted to the lower motor neurones

121
Q

D) Upper motor neurones

A

Neurones which synapse onto interneurones (relay) or lower motor neurones

122
Q

D) Lower motor neurones

A

Neurones which directly innervate muscles/glands

123
Q

What are the main 2 descending tract groups

A

Pyramidal and extrapyramidal

124
Q

D) Pyramidal tracts

A

Tracts which cause voluntary control of muscles. Originates in the cerebral cortex

125
Q

D) Extrapyramidal tracts

A

Tracts which cause the involuntary/autonomic control of muscles. Originates in the brainstem

126
Q

What is the clinical significance of the internal capsule

A

Conscious ascending and descending tracts pass through it. It is susceptible to compression from haemorrhagic strokes = lacunar

127
Q

What are the 2 types of pyramidal tracts + their function

A

Corticobulbar = head and neck
Corticospinal = body

128
Q

D) Pain (important def)

A

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage

129
Q

D) Nociception

A

The neural processes involved in producing a sensation of pain

130
Q

D) Nociceptor

A

First order afferent sensory neurones that are activated by noxious stimuli + have free nerve endings

131
Q

D) Acute pain

A

Less than 12 weeks

132
Q

D) Chronic pain

A

More than 12 weeks or greater than the tissue healing time

133
Q

D) Nociceptive pain + feeling

A

Pain as a result of damage to non-neural tissue, activation of nociceptors
- Aching, localised

134
Q

D) Neuropathic pain + feeling

A

Pain causes by damage to the somatosensory nervous system
- Shooting, burning

135
Q

D) Nociplastic pain

A

Pain that is neither nociceptive or neuropathic in nature

136
Q

Allodynia vs hyperalgesia

A

Pain from a stim that normally does not cause pain vs increased pain from a painful stim

137
Q

What sensory tract transmits pain

A

Lateral spinothalamic

138
Q
A
139
Q

Pain: What are the features of the first order neurones

A
  • Pseudounipolar
  • Un encapsulated
  • Cell body in the dorsal root ganglion
140
Q

Pain: What are the features of the 2nd order neurones

A
  • Cell body in the rexed laminae of the spinal cord
  • Decussate in anterior white commisure of spinal tract to form a + lateral spinothalamic –> Lateral is for pain
141
Q

Pain: What are the features of the 3rd order neurones

A
  • Cell body located in the ventral posterolateral nucleus of thalamus
  • Terminate in primary sensory cortex
142
Q

Where do pain fibres decussate

A

In the anterior white commissure a few levels above point of entry to form anterior + lateral spinothalamic

143
Q

D) Free nerve endings

A

Unencapsulated cutaneous receptors

144
Q

How does the size of the receptive field of a nociceptor relate to the pain felt

A

The smaller the size of the receptive field, the greater the sensory acuity so the more sensitive the area will be

145
Q

Do receptive fields overlap

A

Yes, overlapping receptive fields reduce the precision of perception

146
Q

How does the size of the receptive field relate to the representation in the somatosensory cortex

A

The smaller the receptive field, the greater the cortical representation

147
Q

Where are nociceptors not found

A

In the brain

148
Q

Are nociceptors specific or generalised

A
  • There are different nociceptors for different stimuli but also polymodal nociceptors which respond to multiple types
149
Q

Pain: How are signals transmitted from the nociceptors to the dorsal horn of the spinal cord

A

Specific nociceptors = type A delta fibres
Polymodal nociceptors = type C fibres

150
Q

Pain: What are features of type Alpha delta fibres

A
  • Myelinated, fast conduction
  • Responsible for initial localised pain
  • Small receptive field
151
Q

Pain: What are features of type C fibres

A
  • Unmyelinated, slow conduction
  • Responsible for dull, throbbing secondary pain
  • Large receptive field
152
Q

Pain: What is the difference in firing threshold for A delta vs C type fibres

A
  • A delta fibres have a lower threshold but C fibres can be sensitised eg hyperalgesia
153
Q

Pain: Where do 1st order neurones terminate + what neurotransmitter is released

A

A delta type = Rexed laminae I, glutamate
C type = Rexed laminae II, substance P+ glutamate

154
Q

Why does substance P cause long lasting pain

A

Remains bound to the receptor for a longer period of time

155
Q

How can sensitisation (hyperalgesia) occur

A

1) Peripheral sensitisation
2) Central sensitisation –> increase in the number of NMDA receptors which respond to glutamate
= hyperexcitatability

156
Q

D) Descending modulation of pain

A
  • The hypothalamus and cortical regions process painful stimuli and cause the release of endogenous opioids
157
Q

D) What are the endogenous opioids

A

B endorphins
Dynorphins
Enkephalins

158
Q

How do opioid receptors work

A

Presynaptic membrane of 1st order = reduce neurotransmitter release
Postsynaptic membrane of 2nd order = cause hyperpolarisation
–> reduces pain signal transmission

159
Q

What is the Gate control theory of pain

A

A non-painful input can close the ‘gate’ to painful inputs, so prevents pain sensations from being perceived and felt

160
Q

What factors affect 2 point discrimination

A

The density of sensory receptors + the size of neuronal receptive fields

161
Q

D) Sensory acuity

A

How accurately a stimulus can be located

162
Q

What does UMN refer to in clinical practice

A

The descending pyramidal tracts

163
Q

What neurotransmitter is used by upper motor neurones

A

Glutamate

164
Q

What does the motor homunculus show

A

That areas of the body that have greater precision of motor control have greater cortical representation

165
Q

Symptoms of UMN damage

A
  • Muscle weakness/paralysis
  • Hypertonia due to reduced descending inhibition
  • Hyperreflexia as UMN limits reflexes
  • Spasticity = increased muscle tone on passive movement in a velocity dependent manner
  • Positive babinski sign = splayed toes
  • Clonus = involuntary muscle contraction
166
Q

Is a lower motor neurones’ cell body in the PNS or CNS

A

CNS - in the ventral horn or brainstem for motor cranial nerves

167
Q

What are the 2 types of lower motor neurones

A
  • Alpha motor neurones
  • Gamma motor neurones
168
Q

What do alpha motor neurones do

A

Cause the contraction of muscle fibres that they innervate (extrafusal)

169
Q

How are lower motor neurones (both alpha and gamma) organised in the ventral horn

A

Somatotopically - medial innervates more proximal

170
Q

What does LMN refer to in clinical practice

A

Alpha motor neurones

171
Q

What do gamma motor neurones do

A

The regulation of muscle tone and allow non-conscious proprioception to be maintained - goes from extrapyramidal tract

172
Q

What do gamma motor neurones innervate

A

The intrafusal muscle spindle

173
Q

What are the two components of the muscle that allow for unconscious proprioception

A

Golgi tendon organs
Muscle spindle

174
Q

What is the sensory innervation of the muscle spindle and golgi tendon organs

A

Group A alpha)

175
Q

What do golgi tendon organs do

A

Sensory receptor that senses muscle tension. Transmits info to the spinocerebellar tracts

176
Q

What do muscle spindle do

A

Allows muscle to remain sensitive to stretch and involved in muscle stretch reflexes. Sensory via la sensory afferents, motor innervation by gamma motor neurones

177
Q

What can the GTO do under extreme tension

A

Under extreme tension, the GTO can inhibit the muscle from contracting via temporarily inhibiting muscle spindle activity

178
Q

What are signs of LMN damage

A
  • Hyporeflexia
  • Hypotonia/atonia
  • Muscle weakness/paralysis
  • Fasciculations = when alpha motor neurones are damaged, they can cause random contractions of motor units resulting in twitching
  • Muscle atrophy from loss of neurotrophic factors from alpha motor neurones
179
Q

Disuse atrophy

A

Caused by UMN damage

180
Q

D) Motor unit

A

A single alpha motor neurone and all the muscle fibres it innervates

181
Q

D) Motor pool

A

All the lower motor neurones (both alpha and gamma) that innervate a single muscle

182
Q

What is spinal muscular atrophy

A

Autosomal recessive resulting in the loss of lower motor neurones. There are 4 types

183
Q

What cartilage is the pinna

A

elastic

184
Q

What makes up the external acoustic meatus

A

1/3 elastic cartilage, 2/3 temporal bone

185
Q

What are the auditory ossicles

A

Maleus, incus and stapes

186
Q

What does the stapes attach to

A

The oval window

187
Q

What is the structure of the cochlear

A

2.5 turns of bony tube filled with fluid. Has 2 openings - oval window and round window

188
Q

What are the three compartments of the cochlear

A

scala vestibuli, scala media, scala tympani

189
Q

What fluid is found in the scala vestibuli and tympani vs media

A

Scala vestibuli + tympani = perilymph (basically ECF, lots of Na+)
Scala media = endolymph (lots of K+)

190
Q

What structure connects the scala vestibuli and tympani

A

the helicotrema

191
Q

What is the hearing process up until the oval window

A

1) Outer ear directs sound to tympanic membrane
2) Ossicles conduct and amplify sound due to smaller SA
3) Stapes vibrates the membrane of the oval window

192
Q

What is the hearing process from the oval window onwards

A

1) Vibrations are passed to the perilymph of the scala vestibuli
2) Vibrations pass round to the scala tympani via the helicotrema
3) The vibrations cause the elastic basillar membrane to move up and down
4) Inner hair cells (sterocilia) push against the stiff tectoral membrane
5) Shearing forces cause mechanically gated K+ channels to open –> depolarisation of auditory fibres

193
Q

Inner vs outer hair cells

A

Inner hair cells = do mechanical transduction, afferent fibres
Outer hair cells = do fine tuning, efferent fibres

194
Q

What is the ratio of inner: outer hair cells

A

1:3

195
Q

How does the structure of the basilar membrane relate to hearing

A

Base (start of cochlea) = stiffer, thinner, higher frequency
Apex (final turn) = wider, floppier, lower frequency

196
Q

What are the two possible auditory pathways

A

1) Primary (lemniscal) pathway = main pathway, conscious. Auditory information goes to primary auditory cortex
2) Non-lemniscal pathway = involved in unconscious perception. Attention, emotional response, reflexes

197
Q

After the organ of corti, what is the auditory pathway

A
  • Inferior colliculus (midbrain)
  • Medial geniculate body (thalamus)
    –> primary auditory cortex only for main pathway
198
Q

Nicotinic vs Muscarinic receptors

A
  • Nicotinic receptors are found at neuromuscular junctions (inotropic)
  • Muscarinic receptors are found at smooth muscle + glands (metabotropic)
199
Q

D) Association fibres

A

Fibres that link cortical regions in one hemisphere

200
Q

D) Commissural fibres

A

Fibres that link similar functional areas in the two cortical hemispheres

201
Q

D) Projection fibres

A

Fibres that link the cortex with subcortical structures

202
Q

Example of commissural fibre

A

Corpus callosum

203
Q

Example of projection fibres

A

Internal capsule, corona radiata

204
Q

Do the peripheral limbs have commissural fibres

A

no

205
Q

What artery supplies brocas area

A

the middle cerebral

206
Q

What artery supplies wernickes area

A

the middle cerebral

207
Q

What are the key points of the sensory/motor homunculus

A

Lateral = tongue/lips
Medial = foot

Medicine (15 decks)

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