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Phase 1 Med > Neuro > Flashcards

Neuro Flashcards

1
Q

What does white matter contain?

A

myelinated neurons

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2
Q

What does grey matter contain?

A

cell bodies no myelin sheath

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3
Q

What is the role of oligodendrocytes?

A

myelinate axons in the brain (CNS only)

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4
Q

What is the role of Schwann cells?

A

Myelinate axons in the rest of the body (PNS)

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5
Q

What are commissures?

A

tracts connecting one hemisphere to another = cross at the midline

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6
Q

what are fasciculi?

A

bundles of fibres

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7
Q

What is a capsule?

A

sheet of white matter fibre that borders a nucleus of grey matter

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8
Q

What are nuclei?

A

collection of nerve cell bodies within the CNS

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9
Q

What are ganglia?

A

collection of cell bodies outside the CNS

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10
Q

What is the role of the frontal lobe

A
  • voluntary contralateral motor movement
  • Frontal lobe of the dominant hemisphere contains Broca’s area: controls speech production and writing
  • intellectual functioning, thought processes, reasoning and memory
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11
Q

What is the role of the parietal lobe?

A
  • receives and interprets sensations, pain, touch, pressure and proprioception
  • contains primary somatosensory cortex
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12
Q

What is the role of the temporal lobe?

A
  • Contains primary auditory cortex
  • Wernicke’s area in superior temporal gyrus
  • Understanding of spoke word, emotion and memory
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13
Q

What is the role of the occipital lobe?

A
  • Understanding visual images and the meaning of words

- Contains the primary visual cortex in the calcarine sulcus - stria of Gennari

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14
Q

What is the role of the thalamus?

A

relay centre and directs inputs to higher cortical areas

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15
Q

What is the role of the hypothalamus?

A

Links the endocrine system to the brain

- involved in homeostasis

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16
Q

What structures make up the basal ganglia?

A

The striatum: putamen and caudate nucleus.

  • Globus pallidus: internal and external segments.
  • Subthalamic nucleus.
  • Substantia nigra.
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17
Q

What makes up the striatum?

A

Caudate+ Putamen

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18
Q

What makes up the lentiform nucleus?

A

Globus palladus+Putamen

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19
Q

Which artery supplies the basal ganglia nuclei?

A

Lenticulostriate artery

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20
Q

What is the role of the cerebellum?

A

Precise control, fine adjustment and coordination of motor activity based on continual sensory feedback. The cerebellum decides HOW you do something. It computes motor error and adjusts commands and projects it back to the motor cortex.

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21
Q

Name the connections of the cerebellum and name the parts of the midbrain they correspond to?

A

Superior cerebellar peduncle - midbrain

Middle cerebellar peduncle - pons

Inferior cerebellar peduncle - medulla

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22
Q

What structures lie anteriorly to the cerebellum?

A

The pons and medulla. The 4th ventricle lies in between these and the cerebellum.

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23
Q

What are some symptoms of the cerebellar injury?

A

DANISH

  • dysdiadokinesia- inability to perform rapid alternating movements
  • ataxia - no coordination of speech, balance and walking
  • Nystagmus - random eye movements
  • Intentional tremor
  • Slurred speech
  • hypotonia
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24
Q

Name the different parts of the midbrain

A

Tectum - contains superior and inferior colliculi
cerebral peduncle contains tegmentum and crus cerebri
tegmentum and crus cerebri separated by substantia nigra

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25
Q

What is the role of the pons?

A

acts as a bridge to the cerebellum

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26
Q

Name two cell types found in the CNS?

A
  • nerve cells/neurons

- neuroglia

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27
Q

Name three neuroglia cells

A
  • astrocytes
  • oligodendrocytes
  • microglia
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28
Q

What is the role of the hippocampus?

A
  • part of limbic system
  • episodic memory
  • short term memory
  • navigation
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29
Q

How do modern imaging techniques show neurally active brain regions?

A
  • neurally active regions require more O2
  • More blood flow to that area
  • imaging can detect haemodynamic changes
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30
Q

Name four basic components of a neuron?

A
  • Dendrites
  • Cell body
  • Axon
  • Presynaptic terminal
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31
Q

What is the difference between a nerve fibre and a nerve?

A

Nerve fibre is a single axon and a nerve is a bundle of axons bound together by connective tissue

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32
Q

Where are the afferent cell bodies and the long axons situated?

A
  • outside CNS
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33
Q

Where are the efferent cell bodies and the long axons situated?

A
  • within CNS
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34
Q

what is the role of interneurons?

A

Connect neurons within the CNS

Lie entirely within the CNS

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35
Q

What is the composition of myelin?

A

70% lipid/30% protein

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36
Q

How many axons can each oligodendrocyte myelinate?

and how is this different to Schwann cells

A

as many as 40 axons

Schwann cells are only able to myelinate short segments of one axon

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37
Q

Where are myelinated axons commonly found?

A

Somatic nerves, sensory-motor systems and muscle/spinal systems

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38
Q

Where are unmyelinated axons commonly found?

A

Postganglionic autonomic fibres, where speed is not required

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39
Q

Name two ways in which glial cells support neurons?

A
  • provide physical support

- provide metabolic support e.g pumping metabolic products into the neurons

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40
Q

Name two ways in which oligodendrocytes support the CNS

A

1) single oligodendrocyte can Myelinate up to 40 axons, rapid conduction
2) provide metabolic support by transporting metabolic products directly into axons

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41
Q

Name four ways in which astrocytes provide support to the neurons?

A

1) regulate the composition of extracellular fluid - remove Neurotransmitters and K+ ions around synapses
2) Stimulate the formation of tight junctions between the cells that make up the walls of capillaries found in the CNS - BBB
3) astrocytic end feet contribute to BBB
4) provide metabolic support - removes ammonia and provides glucose

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42
Q

Which is the most numerous glial cell in the CNS

A

Astrocytes

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43
Q

What is the role of radial glia?

A

Guiding developing neurons in the developing brain

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44
Q

What is the role of Muller glia?

A

Specialised radial glia of the retina

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45
Q

What is the role of Bergmann glia?

A

Found in the cerebellum - support Purkinje cells, dendrites and synapses

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46
Q

What is the role of microglia?

A

Specialised macrophage-like cells that perform immune functions in the CNS

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47
Q

Where are ependymal cells found?

A

in the ventricles and the spinal cord

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48
Q

What is the role of ependyma?

A

Provides a barrier between CSF and brain

- has cilia, microvilli and desmosomes

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49
Q

Name 4 things that contribute to the Blood-brain barrier?

A
  • endothelial tight junctions
  • pericytes
  • astrocyte end feet
  • continuous basement membrane (no fenestrations)
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50
Q

Where does CSF circulate?

A

through the subarachnoid space - offers protection for the brain

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51
Q

How many ventricles are there in the brain?

A

4 - lateral (paired) , 3rd and 4th

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52
Q

What connects the ventricles to the subarachnoid space?

A

Cisterns

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53
Q

Which cells produce CSF

A

ependymal cells - in the choroid plexus

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54
Q

What is the choroid plexus?

A
  • modified ependymal cells

- form around a network of capillaries, large surface area

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55
Q

Where is CSF absorbed and what absorbs the CSF?

A
  • in the Superior sagittal sinus
  • Absorbed by arachnoid villi
  • aggregation of arachnoid villi is called arachnoid granulations
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56
Q

How is the neuronal resting potential maintained?

A

3Na+ are pumped out of the cell for every 2K+ pumped in. This process requires ATP. There are many Na+/K+ transport pumps.

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57
Q

what is the range of membrane potentials in an action potential

A

-70mv to +30mv

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58
Q

What is the relative refractory period?

A

It follows the absolute refractory period and is a time during which a 2nd stimulus that is stronger than the first is needed to produce another AP.

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59
Q

What are the 2 components of a refractory period?

A

The absolute refractory period is followed by the relative refractory period.

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60
Q

What is the absolute refractory potential?

A

when the sodium channels are completely inactivated

no matter how strong the second stimuli there will not be a second action potential

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61
Q

what is the reason why we have refractory periods?

A

so individual electrical signals can be passed along the axon

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62
Q

Name two factors that determine the propagation speed

A

fibre diameter

myelination

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63
Q

Neurones communicate via 2 types of synapses. What are they?

A
  1. Chemical - majority.

2. Electrical.- rapid

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64
Q

Describe neurotransmitter release

A

Voltage-gated Calcium channels open when an action potential reaches the pre-synaptic membrane

  • Ca2+ causes vesicles to move and fuse with the presynaptic membrane
  • neurotransmitter released and diffuses to receptors
  • attaches to receptors
  • enzyme breaks down neurotransmitter - e.g acetylcholine esterase
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65
Q

Describe two effects of a neurotransmitter on the postsynaptic membrane

A

Excitatory channels cause depolarisation - much Na+ leaves and few K+ enter
Inhibitory channels lead to hyperpolarisation - much K+ leaves and many Cl- enters

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66
Q

Describe temporal summation

A

inputs from same presynaptic cell at different times - greater number of ion channels open

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67
Q

Describe spatial summation

A

Two inputs occur at different locations in the postsynaptic neurone

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68
Q

How do local anaesthetics work?

A
  • Interupt axonal neurotransmission
  • blocking sodium channels
  • no action potentials
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69
Q

What are neurons that release Ach called?

A

cholinergic neurons

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70
Q

What is the major neurotransmitter at neuromuscular junctions?

A

Ach

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71
Q

Name two receptors that Ach bonds to

A

nicotinic

muscarinic

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72
Q

Where is dopamine commonly used?

A

Basal ganglia

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73
Q

What do antiparkinson drug contain?

A

L-DOPA which is the precursor for dopamine

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74
Q

What is the main excitatory and main inhibitory neurotransmitter?

A

excitatory - Glutamate

inhibitory - GABA

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75
Q

In which skull bone is the middle located?

A

temporal bone

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76
Q

which nerve provides sensation to the middle ear?

A

Glossopharyngeal

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77
Q

which tube equalises pressure between the inside and outside of the ear?

A

eustachian tube

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78
Q

Name the three bones in the inner ear which oscillate

A

Malleus, incus and stapes

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79
Q

what type of joints do the Malleus, stapes and incus have between them?

A

Synovial joints

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80
Q

Where does the stapes carry the vibrations too?

A

oval window

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81
Q

why is the force per area increased from the tympanic membrane

A

Oval window is much smaller then the tympanic membrane

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82
Q

Name two muscles in the ear along with attachment and innervation

A

Tensor tympani - attaches to malleus and innervated by mandibular branch of trigeminal
Stapedius - attachment to stapes and innervated by the facial nerve

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83
Q

can tensor tympani and stapedius protect the ear from sudden loud sounds?

A

No - only from continuous loud sounds

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84
Q

What is the cochlea?

A

it is a spiral shape

  • coiled 2.5 times
  • fluid-filled space
  • in the temporal bone
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85
Q

what divides the cochlea lengthwise?

A

cochlear duct

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86
Q

What is the cochlear duct filled with?

A

endolymph - high concentration of K+ and low concentration of Na+

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87
Q

What is the scala vestibuli and scala tympani filled with

A
  • Perilymph - high concentration of Na+ and low concentration of K+
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88
Q

What makes the scala vestibuli and scala tympani continous?

A

helicotrema - small deformity at end of the cochlea which allows pressure waves to move from SV to ST

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89
Q

What relieves the pressure in the cochlea?

A

Round window

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90
Q

Describe the base of the basilar membrane?

A

Narrow and stiff - sensitive to high frequencies of sound

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91
Q

Describe the apex of the basilar membrane

A

Wider and less stiff - sensitive to lower frequencies of sound

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92
Q

How do stapedius and tensor tympani change the stiffness of the ossicular chain?

A

They control the mobility of malleus and stapes and so protect the inner ear from loud noises.

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93
Q

What nerve provides general sensation to the outer ear?

A

vagus - CN10

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94
Q

How many rows are there of:

a) Inner hair cells?
b) Outer hair cells?

A

a) 1 row of IHC’s.

b) 3 rows of OHC’s.

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95
Q

What structures are present on the IHC’s and OHC’s?

A

Stereocilia

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96
Q

What structures connect adjacent stereocilia?

A

Tip links.

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97
Q

What happens to the stereocilia when the basilar membrane vibrates?

A
  • stereocilia bend towards the tallest member of bundle TIP links open K+ channels
  • influx of K+ from potassium-rich endolymph therefore depolarising
  • opens voltage-gated calcium channels
  • triggers neurotransmitter release
  • glutamate released and action potential in the cochlear branch of 8th CN
  • bending in opposite direction slackens tip links allowing repolarisation
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98
Q

True or False; antibiotics can damage stereocilia.

A

True!

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99
Q

Describe the auditory pathway

A

ECOLIMA

  • eighth cranial nerve
  • Cochlear nuclei
  • superior olivary nucleus
  • Lateral lemniscus
  • inferior colliculi
  • medial geniculate body
  • primary auditory cortex in temporal lobe
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100
Q

What is the Chorda tympani responsible for?

A

Branch of the facial nerve

- conveys tase from the anterior 2/3 of tongue and runs through middle ear

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101
Q

What fills the vestibular apparatus?

A

endolymph

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102
Q

What is the function of the vestibular system?

A

Balance, spatial orientation, proprioception

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103
Q

What does the vestibular apparatus consist of?

A

Three semicircular canals
Utricle and Saccule
lie in the temporal bone

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104
Q

What do the semi-circular canals detect?

A

Angular acceleration/rotation

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105
Q

Describe the arrangement of receptor cells in the semicircular canals?

A

Stereocilia encapsulated in a gelatinous mass called the cupula at the Ampulla of each canal. When the head moves the fluid doesn’t move, the Cupula is pushed against the fluid

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106
Q

Describe what happens when the stereocilia are bent in the semicircular canals?

A

Ampulla pushed against stationary fluid
- bending of stereocilia
- alteration in the rate of release of glutamate
- Glutamate synapses with neurons
- Glutamate released at rest
- Direction of bending relates to increase/decrease the release
- Towards largest member of hair cells - depolarisation
- Away from largest member leads to hyperpolarisation
-

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107
Q

What do the Utricle and Saccule detect?

A

Linear acceleration
utricle - vertical
- saccule horizontal

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108
Q

How does the body use vestibular information?

A

Controls eye movements
reflex mechanisms
proprioception

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109
Q

Name the two components of the outer eye

A

Cornea and Sclera

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110
Q

What is the role of the cornea?

A

transmission of light and refraction

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111
Q

Name the three layers of the cornea

A

epithelium, stroma and endothelium

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112
Q

What is the role of the endothelium layer in the cornea?

A

To pump water out of stroma as water makes the space between collagen fibres opaque

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113
Q

Which layer of the cornea is not capable of repair?

A

endothelium

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114
Q

What is the Sclera and what is its role?

A

The white capsule around the eye
protection as made from the tough outer layer of collagen
the insertion point of extraocular muscles
continuation of dura and cornea

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115
Q

Name three layers in the middle (uvea) layer of the eye?

A

Iris
ciliary body
choroid

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116
Q

What is the role of the iris?

A

controls the size of the pupil and gives eye colour

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117
Q

Which muscles are present in the iris which constrict/dilate the pupil?

A

Sphincter pupillae - parasympathetic

dilator muscles - make the pupil larger - sympathetic

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118
Q

What is the role of the ciliary body?`

A
  • glandular epithelium
  • accommodation
  • production of aqueous humour to maintain intraocular pressure
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119
Q

Where does the ciliary body receive its innervation?

A

Parasympathetic system

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120
Q

Describe what occurs in accommodation?

A
  • The optic nerve takes sensory information for pupillary light reflex and vision
  • oculomotor nerve carries motor function for accommodation
  • ciliary body contracts
  • suspensory ligaments slacken
  • lens becomes more rounded for close vision
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121
Q

describe the role of Choroid

A
  • Connective tissue with blood vessels
  • provides nutrition to the outer retina
  • acts as a heat sink
  • darkly pigmented to absorb stray photons
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122
Q

Why is the choroid darkly pigmented?

A

darkly pigmented to absorb stray photons

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123
Q

What does the retina produce?

A
  • Vitreous humour maintains intraocular pressure and collagen structure, important in the transmission of light
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124
Q

Which photoreceptors are the most numerous in the Fovea Centralis?

A

Cone cells

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125
Q

Which photoreceptors are the most numerous in the Macula Lutea?

A

Rod cells

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126
Q

What are the functions of cones in the eye?

A

Cones are important for visual acuity and colour vision.

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127
Q

What are the functions of rods in the eye?

A

Rods are important for peripheral vision.

  • sensitive to light
  • vision in low light
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128
Q

Describe the three layers of the tear film

A
  • anterior lipid layer - provides a hydrophobic layer to prevent the aqueous layer evaporating
  • Middle aqueous layer - secreted by lacrimal glands, regulates transport through the cornea, prevents infections
  • posterior mucus - provides a hydrophilic layer, secreted by goblet cells, even distribution of tear film
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129
Q

Describe the visual pathway

A

1) visual field
2) retina
3) photoreceptors
4) bipolar cells
5) ganglion cells
6) optic nerve
7) optic chiasm
8) optic tract
10) lateral geniculate body
11) Meyer’s/Baum’s loop
12) primary visual cortex

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130
Q

Describe the ocular arteries that comes from the internal carotid artery

A
  • Ophthalmic artery
  • Central retinal artery into the optic nerve
  • ciliary arteries
  • lacrimal artery
  • ethmoid and eyelid artery
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131
Q

Name the artery that comes of the external carotid artery and what does it supply?

A

Facial artery - supplies medial lid and orbit

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132
Q

Which fibres cross at the optic chiasm and which stay ipsilateral?

A

Nasal portion - carrying temporal visual fields cross at the optic chiasm and nasal visual fields stay on same side

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133
Q

What is the loop of optic radiation responsible for the upper visual field called?

A

Meyer’s loop. It travels through the temporal lobes.

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134
Q

Which lobes of the brain does the loop of optic radiation responsible for the lower visual field travel through?

A

Travels through the parietal lobes. - Baums loop

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135
Q

What would be the affect on the visual field if there was a complete lesion of the left optic nerve?

A

Total left eye blindness.

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136
Q

What would be the effect on the visual field if there was a complete lesion of the optic chiasm?

A

Bipolar hemianopia. (Left eye - left-sided blindness, right eye - right-sided blindness).

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137
Q

What would be the effect on the visual field if there was a complete lesion of the right optic tract?

A

Left homonymous hemianopia. (Left side blindness of both eyes).

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138
Q

What would be the affect on the visual field if there was a lesion of the meyer’s (temporal) loop of the left optic radiation?

A

Right homonymous superior quadrantanopia. (Right upper quadrant of both eyes affected).

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139
Q

What would be the affect on the visual field if there was a lesion of the parietal loop of the left optic radiation?

A

Right homonymous inferior quadrantanopia. (Right lower quadrant of both eyes affected).

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140
Q

Name six extraocular muscles

A
  • medial rectus
  • lateral rectus
  • superior rectus
  • inferior rectus
  • superior oblique
  • inferior oblique
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141
Q

What are intortion and extortion?

A

Intortion is rotation towards the midline

Extortion is rotation away from midline

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142
Q

which extraocular muscles does the oculomotor nerve innervate?

A
  • Medial rectus
  • superior rectus
  • inferior rectus
  • inferior oblique
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143
Q

Where is the nucleus for cranial nerve 3?

A

In periaqueductal grey near the cerebral aqueduct

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144
Q

What is the innervation of the lateral rectus?

A
  • CN6 Abducens
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145
Q

What is the innervation of the Superior oblique?

A
  • CN4 trochlear
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146
Q

Where is the nucleus for the trochlear nerve located

A

In periaqueductal grey near the cerebral aqueduct

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147
Q

Describe the action of the superior rectus on the eye

A
  • Elevates
  • Medial rotation
  • adduction
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148
Q

Describe the action of superior oblique on the eye

A
  • Depresses
  • medial rotation
  • abduction
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149
Q

Describe the action of the inferior rectus on the eye

A
  • depresses
  • lateral rotation
  • adduction
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150
Q

Describe the action of the inferior oblique

A

Elevation, abduction, lateral rotation of the eyeball

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151
Q

Describe the action of levator palpebrae superioris

A

Elevation of the upper lid

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152
Q

Which muscle elevates the upper eyelid?

A

levator palpebrae superioris

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153
Q

Describe the action of the medial rectus?

A

Adduction of the eyeball

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154
Q

Describe the action of the lateral rectus?

A

Abduction of the eyeball

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155
Q

Which nerve innervates the superior oblique?

A

Cranial nerve 4 - trochlear

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156
Q

What does the somatic nervous system innervate?

A

Skeletal muscle - only excitation

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157
Q

Where are the cell bodies of somatic neurons found?

A

Ventral horn of spinal cord

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158
Q

Which nervous system travels from the CNS to the effector without any synapses

A

Somatic nervous system - to skeletal muscles

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159
Q

Which neurotransmitter is involved in the somatic nervous system

A

Ach

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160
Q

What does the autonomic nervous system innervate?

A

Smooth muscle
glands
cardiac muscle
neurons in the enteric system

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161
Q

How do somatic motor neurones differ from autonomic motor neurones?

A

The somatic motor neurone leaves the spinal cord and synapses straight onto the effector, only excitatory. Autonomic motor neurones have a pre-ganglionic and post-ganglionic component and so synapse at the ganglia and then at the effector. can be excitatory or inhibitory

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162
Q

Which neurotransmitters are used in the autonomic nervous system neuron chain?

A

Ach used before ganglion

Ach (excitatory) or noradrenaline used after the ganglion ( inhibitory)

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163
Q

Where do sympathetic nerves come from?

A

T1 -> L2 spinal nerves.

164
Q

What neurotransmitter do sympathetic and parasympathetic nerves both use at ganglia?

A

Ach.

165
Q

What neurotransmitter do parasympathetic nerves use at organs?

A

Ach.

166
Q

What neurotransmitter do sympathetic nerves use at organs and what receptor is involved?

A

Noradrenaline. adrenergic receptors

167
Q

What receptors are present in the preganglionic synapse?

A

nicotinic receptors

168
Q

Does the parasympathetic or sympathetic system have more ganglia?

A

sympathetic

169
Q

What neurotransmitters and receptors are used at pre and postganglionic synapses in the parasympathetic nervous system?

A

Ach/nicotinic - preganglionic

Ach/mucuranic - postganglionic

170
Q

What is the enteric nervous system?

A
  • autonomic nervous system of GI tract

- independent of the autonomic nervous system

171
Q

What is a motor unit?

A

An alpha motor neurone, type of lower motor neurone and all extrafusal skeletal fibres it innervates

172
Q

how do motor units relate to greater variations of movement?

A

Fewer fibres innervated by an alpha motor neuron the greater the variation of movement

173
Q

Where are alpha motor neurons that control distal muscles located?

A

laterally in the spinal cord

174
Q

Where are alpha motor neurons that control proximal muscles located?

A

medially in the spinal cord

175
Q

What is a neuromuscular junction?

A

A chemical synapse formed by the contact between a motor neurone and a muscle fibre.

176
Q

Which neurotransmitter is used at neuromuscular junctions?

A

Ach - bind to cholinergic nicotinic receptors

177
Q

What is the region of muscle fibre plasma membrane that lies under the terminal portion of the axon?

A

Motor end plate

178
Q

Why are most neuromuscular junctions located in the middle of muscle fibres?

A

So action potentials can be propagated in both directions

179
Q

What information do muscle spindles provide?

A
  • muscle length

- rate of change of muscle length

180
Q

what are the receptors wrapped around muscle fibres in the muscle spindle?

A

Peripheral endings of afferent nerve fibres wrapped around intrafusal muscle fibres

181
Q

What neurones innervate muscle spindles and why?

A

Gamma motor neurones. - to prevent slack and optimise stretch detection

182
Q

Which area of the muscle spindle is non-contractile?

A

the central portion

183
Q

What are muscles spindles composed of?

A

Intrafusal fibres. (They are embedded in muscle - extrafusal fibres).

184
Q

Which type of sensory nerve is the middle third of the muscle spindle associated with?

A

Fast type 1a afferent sensory nerves

185
Q

Which type of sensory nerve is the superior and inferior thirds of the muscle spindle associated with?

A

slower type 2 afferent sensory nerves

186
Q

why is alpha-gamma coactivation used?

A

prevent loss of information, prevent slack when muscle contracts, increases the sensitivity of detection

187
Q

What do Golgi tendon organs measure?

A

Measure tension which depends on muscle length, load and muscle fatigue

188
Q

What are Golgi tendon organs?

A

the ending of afferent fibres that wrap around collagen bundles in the tendons, collagen bundles are slightly bowed when resting

189
Q

What nerve fibres innervate golgi tendon organs?

A

Afferent type 1b sensory nerve fibres (inhibitory).

190
Q

How do Golgi tendon organs detect stretch?

A

tension straightens the collagen bundles in tendons - distorts Golgi tendon receptor endings, activates them

191
Q

What is the response of Golgi tendon organs if they detect a change in tension?

A

The afferent 1b fibres inhibit alpha motor neurones to prevent muscle contraction if the force gets too great.

  • stimulate motor neurons of antagonist’s muscles
  • inverse stretch reflex
192
Q

Which one has faster detection? Golgi tendon organs or muscle spindles

A

Muscle spindles

type 1a afferent are much faster than type 1b afferent

193
Q

What are spinal reflexes?

A
  • Involuntary, physiological responses to stimuli e.g. withdrawing your hand when you touch something hot.
  • Unlearned and instinctive: unconditioned responses.
194
Q

Withdrawal reflex: what does reciprocal innervation of antagonistic muscles explain?

A

It explains why the contraction of one muscle induces the relaxation of the other; this permits the execution of smooth movements.

195
Q

What is the stretch reflex?

A

A very simple, monosynaptic reflex. If a muscle is stretched it responds by contracting.

196
Q

Briefly describe the stretch reflex.

A

The muscle is stretched and intrafusal muscle fibres are stimulated -> sends afferent impulses along 1a neurones -> alpha motor neurone -> efferent impulses to extrafusal muscle fibres -> contraction.

197
Q

Briefly describe the withdrawal reflex.

A

The limb is withdrawn from noxious stimuli. Afferent fibres synapse on motor neurones in spinal cord. The response is ipsilateral flexion (same side as noxious stimuli) and contralateral extension.

198
Q

What is muscle tone?

A

Degree of contraction of a muscle or proportion of motor units that are active at any one time

199
Q

What would be the presentation of muscles in hypertonia

A

firm
rigid
resists passive stretch

200
Q

What would be the presentation of muscles in hypotonia

A

Soft
Flaccid
little resistance to stretch

201
Q

An elderly patient presents with a stiff flexed arm, and a stiff extended leg (both on the left) which the patient finds difficult to bend. What is affected?

A

Upper motor neurone – this patient has had a stroke and so the UMN’s are affected.

202
Q

What is a UMN?

A

A neurone that is located entirely in the CNS. Its cell body is located in the primary motor cortex.

203
Q

What are the signs of UMN weakness?

A
  • hypertonia
  • Hyperreflexia.
  • Spasticity.
  • Minimal muscle atrophy.
  • clasp knife reflex - give after a time of resistance
204
Q

What can cause UMN weakness?

A

MS, brain tumour, stroke.

205
Q

What can cause LMN weakness?

A

Slipped disc, neuropathies.

206
Q

What are some signs of LMN weakness?

A
  • Hypotonia
  • weakness
  • muscle atrophy
  • absent reflex response
207
Q

Define nociceptive pain.

A

Pain derived from actual damage to non-neural tissue, it is due to the activation of nociceptors.

208
Q

Define neuropathic pain.

A

Pain caused by a primary lesion or dysfunction of the nervous system.

209
Q

Name two afferent fibres that come from nociceptors?

A

Alpha delta fibre

C fibre

210
Q

Are C fibres myelinated or unmyelinated?

A

Unmyelinated.

211
Q

Describe C fibres.

A
  • They are the smallest nerve fibres.
  • Unmyelinated and so have slow conduction speeds.
  • They have a high activation threshold meaning they detect selectively nociceptive stimuli.
212
Q

Describe A-delta fibres.

A
  • Small nerve fibres but larger than C fibres.
  • Thinly myelinated.
  • They have a high activation threshold.
213
Q

Which neurotransmitter do Alpha delta fibres release?

A

glutamate

214
Q

Which neurotransmitters do C fibres release?

A

Glutamate and Substance P

215
Q

What type of pain are A-delta fibres responsible for?

A

The sensation of a quick, sharp, localised pain; ‘first pain’.

216
Q

What type of pain are C fibres responsible for?

A

C fibres respond to high intensity stimuli. They are responsible for a slow, deep, spread-out pain; ‘second pain’.

217
Q

Briefly describe the pathway of afferent pain transmission.

A

Nociceptors, A delta and C fibres, synapse with secondary afferent neurones in the dorsal horn of the grey matter. Substance P is released. Interaction amongst afferent neurones and interneurons determines the activity of secondary neurones. The signal is carried via the spinothalamic tract to the thalamus. Third-order neurones then ascend to the somatosensory cortex.

218
Q

What is the role of substance P?

A

Slow acting, stay bound to receptors for longer

also a vaso-dilator

219
Q

Where do the optic tracts terminate?

A

Lateral geniculate body in the thalamus.

220
Q

Where is the insula located?

A

Deep in the lateral sulcus.

221
Q

What is the role of the insula in pain recognition?

A

The insula contributes to the subjective perception of pain. It is where the degree of pain is judged.

222
Q

what is the role of the cingulate gyrus?

A
  • linked in the limbic system
  • emotion, learning and memory
  • emotional response to pain
223
Q

What is the role of the cingulate gyrus in pain recognition?

A

It provides an emotional response to pain

224
Q

Where is the periaqueductal grey located?

A

In the midbrain - grey matter surrounding the cerebral aqueduct

225
Q

What is the periaqueductal grey part of and where does it receive inputs from?

A
  • Part of descending pain pathway

- receives input from the somatosensory cortex

226
Q

What does the periaqueductal grey contain?

A
  • high concentration of opioid receptors
227
Q

How can opioids be used as analgesia?

A
  • bind to opioid receptors
  • opioid receptors activated
  • reduction in pre-synaptic neuronal sensitivity
  • reduced substance p release
  • reduced pain sensation
228
Q

What is the Melzack Wall pain gate?

A

The idea that non-painful input can close the ‘gate’ to painful input and so prevent it from reaching the CNS. Non-noxious stimuli can prevent pain as the large fibres can override the small pain fibres. It is a physiological explanation for why ‘rubbing it better can help.

229
Q

What is the function of the basal ganglia?

A
  • inhibits unwanted movement
  • controls posture and movement
  • facilitates voluntary movement and behaviour
  • It determines WHAT you do via a system of inhibition and disinhibition.
230
Q

Where is the primary motor cortex located?

A

Pre-central gyrus of the frontal lobe

231
Q

Describe the direct pathway

A
  • Motor cortex excites the striatum
  • Substantia nigra initiates the direct pathway
  • The excited striatum sends inhibitory signal to the internal globus pallidus (GPi)
  • Inhibited globus pallidus can’t send an inhibitory signal to the thalamus
  • Not inhibited, the thalamus stays active and constantly sends signals to the motor cortex to initiate the movement
232
Q

Describe the indirect pathway

A
  • Motor cortex excites the striatum
  • Substantia nigra initiates the indirect pathway
  • The excited striatum sends an inhibitory signal to the external globus pallidus (GPe)
  • External globus pallidus cannot send an inhibitory signal to the subthalamic nucleus (STN)
  • Not inhibited, the subthalamic nucleus constantly sends signals to - internal globus pallidus (GPi)
  • Excited internal globus pallidus sends an inhibitory signal to the motor cortex
233
Q

Where does the substantial nigra project to?

A

The striatum.

234
Q

Name 4 disorders associated with basal ganglia dysfunction

A
  1. Huntington’s disease.
  2. Parkinson’s disease.
  3. ADHD.
  4. OCD.
235
Q

What is the reason behind the signs of Parkinson’s Disease?

A

Not enough dopamine.

236
Q

What are the signs of Parkinson’s disease?

A
  1. Tremor.
  2. Bradykinesia - slow movements
  3. Rigidity.
237
Q

What is the reason behind the signs of Huntington’s Disease?

A

Too little GABA resulting in Too much dopamine.

238
Q

What are the signs of Huntington’s disease?

A
  1. Chorea (jerky, involuntary movements).
  2. Dementia.
  3. Personality change
  4. overshooting movements
239
Q

Briefly describe how dopamine is produced.

A

Tyrosine -> L-dopa -> dopamine.

240
Q

What is the role of the limbic system?

A

Acts as an interface between the internal environment and the external environment
- emotion, behaviour, long-term memory, olfaction and motivation. It is also thought to have a role in learning.

241
Q

Name the two main functions of the limbic system?

A
  • Learning

- translation of emotional state into appropriate behaviour

242
Q

which structures make up the limbic system?

A
  • Cingulate gyrus
  • hippocampus
  • parahippocampal gyrus
  • fornix
  • corpus callosum
  • mamillary body
  • amygdala
243
Q

What is the papez circuit?

A

A circuit that connects the main structures of the limbic system. It is involved in memory and emotions.

244
Q

describe the pathway of the Papez circuit

A

1)Hippocampus
2)Fimbria
3)Fornix
4)Mamillary body
Mammilothalamic tract
6)Thalamus
7)Cingular gyrus
8)Parahippocampal gyrus
9)Entorhinal cortex

245
Q

What is the role of the amygdala?

A
  • emotional memory

- responsible for fear

246
Q

What is the function of the cerebellum?

A
  • maintenance of posture and balance
  • maintenance of muscle tone
  • coordination of voluntary movement
  • Precise control, fine-tuning and coordination
  • makes modifications to voluntary movement
247
Q

What structures lie anteriorly to the cerebellum?

A

The pons and medulla. The 4th ventricle lies in between these and the cerebellum.

248
Q

What structure connects the two cerebellar hemispheres?

A

The vermis.

249
Q

What are the two fissures of the cerebellum called?

A
  • The primary fissure.

- The horizontal fissure.

250
Q

What are the lobes of the cerebellum hemispheres called?

A

The anterior and posterior lobes.

251
Q

How does the cerebellum control coordination, precision and timing of movements?

A

It compares the brain’s intentions with actual actions and makes any necessary modifications.

252
Q

What do the middle cerebellar peduncles convey?

A

They send information from the primary motor cortex about the motor plan to the cerebellum - corticopontocerebellar tract.

253
Q

What do the inferior cerebellar peduncles convey?

A

Ipsilateral muscle proprioception, balance and vestibular inputs - vestibulocerebellar tract and dorsal spinocerebellar tract. Also fibres from the inferior olivocerebellar tract.

254
Q

What efferent signals do the superior cerebellar peduncles convey?

A

Efferent signals from the dentate nucleus that go to the red nucleus and thalamus.

255
Q

What are the 3 layers of the cerebellar cortex?

A
  • Molecular (outermost).
  • Purkinje - monolayer, synapse with parallel fibres in the molecular layer, receives inputs from climbing fibres
  • Granular - small cells with extensive dendrites, receives inputs from mossy fibres, largest layer, bifurcates in molecular layer to form parallel fibres
256
Q

What are the 2 inputs into the cerebellum?

A
  • Climbing fibres, inferior peduncle, carry information from proprioception and vestibular system
  • Mossy fibres - middle peduncle, comes from pons and cerebral cortex, carriers info from the pontocerebellar pathway
257
Q

What is the output of the cerebellum?

A

Purkinje cell axons - the majority of these axons go to the dentate nucleus - then pass into the superior cerebellar peduncle to decussate and pass into the thalamus and red nucleus

258
Q

Where do the mossy fibres come from?

A

They come from the pons via the middle cerebellar peduncle.

259
Q

Where do the climbing fibres come from?

A

The come from the olivocerebellar nuclei via the inferior cerebellar peduncle.

260
Q

Where do the purkinje cell axons go to?

A

Most go to the dentate nucleus. They then pass into the superior cerebellar peduncle to decussate, and then travel to the thalamus and the red nucleus.

261
Q

Name 4 cerebellar nuclei.

A
  1. Dentate.
  2. Emboliform.
  3. Globose.
  4. Fastigial.
262
Q

What is the affect on movement in cerebellar injury?

A

Movements are slow and uncoordinated.

263
Q

What are the sulci and gyri referred to in the cerebellum?

A

folia and fissures

264
Q

Which neurotransmitter do the Purkinje cells use and what does this mean?

A

Uses GABA - means the output is mediated through inhibition of cerebellar nuclei.

265
Q

To which cerebellar peduncle does the corticopontocerebellar travel through and what does it carry?

A

Middle cerebellar peduncle

Information from the primary motor cortex

266
Q

To which cerebellar peduncle does the Vestibulocerebellar tract travel through and what does it carry?

A

Inferior cerebellar peduncle

Vestibular impulses from labyrinths, via the vestibule nucleus

267
Q

What is the function of the spinocerebellar tracts?

A

They carry unconscious proprioceptive information to the ipsilateral cerebellum.

268
Q

Do the fibres decussate in the spinocerebellar tracts?

A

No! They go to the ipsilateral cerebellum.

269
Q

Name the four spinocerebellar tracts

A
  • Dorsal spinocerebellar tracts
  • anterior spinocerebellar tracts
  • Cuneocerebellar tracts
  • Rostral spinocerebellar tracts
270
Q

Describe the dorsal spinocerebellar tract

A
  • via inferior cerebellar peduncle
  • ipsilateral
  • from both Golgi tendon and muscle spindle
  • upper limbs ascending
271
Q

Describe the anterior spinocerebellar tract

A

Via superior cerebellar peduncle

  • ipsilateral - decussates twice
  • only from Golgi tendon organ
  • upper limbs ascending
272
Q

Describe the cuneocerebellar tracts

A

via inferior cerebellar peduncles

  • ipsilateral
  • both Golgi tendon and muscle spindle
  • upper limbs ascending
273
Q

Describe the rostral spinocerebellar tract?

A

via inferior cerebellar peduncle

  • ipsilateral
  • only Golgi tendon organ
  • upper ascending
274
Q

Name the inputs to the cerebellum and state if they are ipsilateral or contralateral

A

Spinal cord - ipsilateral, proprioceptive information about limb position and movement
Vestibular system - ipsilateral, information about head movement from labyrinth
Motor cortex - contralateral - copies of motor commands

275
Q

Name the outputs of the cerebellum and state whether it is contralateral or ipsilateral

A

Motor cortex - via thalamus - contralateral, Adjustment of cortical motor commands

276
Q

Name 4 ascending spinal pathways.

A
  1. DCML.
  2. Spinothalamic.
  3. Spinocerebellar.
  4. Spinoreticular.
277
Q

What sensations does the DCML pathway convey?

A

Fine touch, 2-point discrimination and proprioception.

278
Q

Describe the DCML pathway

A
  • first-order neurons carry info from peripheral nerves to the medulla
  • Signals from upper limbs (T6 and above) travel in fasciculus cuneatus synapse in nucleus cuneatus
  • Signals from lower limbs travel in fasciculus gracilis synapse in nucleus gracilis
  • second-order neurons
  • From cuneate or gracilis nuclei fibres carry info to 3rd order neurons
  • Decussate in medulla travel to the contralateral thalamus
  • Third-order neurons
  • Transmit sensory info to the thalamus and ipsilateral primary sensory cortex`
279
Q

What sensations does the spinothalamic pathway convey?

A
  • Lateral spinothalamic - pain and temperature.

- Anterior spinothalamic - crude touch and pressure

280
Q

What sensations is the lateral spinothalamic tract responsible for?

A

Pain and temperature.

281
Q

What sensation is the anterior spinothalamic tract responsible for?

A

Crude touch and pressure

282
Q

Describe the spinothalamic tract

A
  • consists of two tracts
  • anterior spinothalamic tract carries crude touch and pressure
  • lateral spinothalamic tract carries pain and temperature
  • First-order neurons arise from sensory receptors in the periphery
  • enter spinal cord and synapse at the tip of the dorsal horn
  • Second-order neurons
  • Carry info from the dorsal horn to the thalamus
  • fibres decussate in the spinal cord
  • Third-order neurons
  • From thalamus to ipsilateral primary sensory cortex
  • Pathways are the same for both tracts
  • Tracts run alongside each other
283
Q

What is the role of spinocerebellar tracts?

A
  • Groups of tracts carrying unconscious proprioceptive information
  • Information carried from muscles to cerebellum
284
Q

What descending pathways are described as pyramidal?

A

Corticospinal and corticobulbar tracts - responsible for voluntary control.

285
Q

Are there any synapses within the descending pathways?

A

No. At the termination of the descending tracts, the neurones synapse with a lower motor neurone. (All the neurones within the descending motor system are UMNs).

286
Q

What are the corticospinal tracts responsible for?

A

The control of voluntary muscles. Anterior - axial muscles. Lateral - limb muscles.

287
Q

Describe the corticospinal tracts.

A

Originate in the primary motor cortex, descends through corona radiata and internal capsule to the medullary pyramids. 90% decussates here and becomes the lateral corticospinal tract; the remaining 10% forms the anterior corticospinal tract. The anterior tract then remains ipsilateral then decussates and terminates in the ventral horn Both tracts terminate in the ventral horn.

288
Q

Describe the corticobulbar tracts.

A

Originate in the primary motor cortex, descends through corona radiata and internal capsule to the brainstem. The fibres terminate on motor nuclei of cranial nerves. They synapse with LMN’s which carry motor signals to the face and neck.
most fibres innervate the nuclei bilaterally, but the Facial nerve and hypoglossal nerve only have contralateral innervation

289
Q

Where do the extrapyramidal tracts originate?

A

The brainstem.

290
Q

Describe the vestibulospinal tract (extrapyramidal)

A

Arise from vestibular nuclei
Medial and lateral tracts
Supply ipsilateral information
Controls balance and posture

291
Q

Describe the reticulospinal tract (extrapyramidal)

A 
Medial tract arises from the pons
Facilitates voluntary movements
Increases muscle tone
Lateral tract arises from medulla
Inhibits voluntary movement
Reduces muscle tone
292
Q

Describe the rubrospinal tract ( extrapyramidal)

A

Rubrospinal tract:
Arises from red nucleus
Fibres decussate and then descend
Plays a role in fine control of hand movement

293
Q

Describe the tectospinal tract (extrapyramidal)

A

Arises from the superior colliculus
Decussate and then enter the spinal cord
Coordinates movements of the head in relation to vision stimuli

294
Q

What descending pathways are described as extrapyramidal?

A

Vestibulospinal, rubrospinal, tectospinal, reticulospinal - responsible for involuntary and automatic control of all musculature, such as muscle tone, balance, posture and locomotion.

295
Q

Name the two extrapyramidal tracts which decussate

A

Rubrospinal and tectospinal

296
Q

What is Brown-Sequard syndrome?

A

Hemi-section of the spinal cord.

297
Q

What would be the signs of Brown-Sequard syndrome?

A
  • ipsilateral loss of proprioception, motor and fine touch

- contralateral loss of pain, temperature and crude touch

298
Q
  • What is the name of CN1
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Olfactory nerve
  • Sensory
  • Olfactory epithelium
  • Olfaction
  • cribriform plate of ethmoid bone
299
Q
  • What is the name of CN2
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • optic nerve
  • sensory
  • Retina
  • Vision, sensory input for pupillary light reflex
  • exits skull via optic canal
300
Q
  • What is the name of CN3
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Oculomotor
  • Motor and parasympathetic
  • all extraocular muscles except superior oblique and lateral rectus/ sphincter pupillae and ciliary muscle of eyeball ( parasympathetic)
  • function movement of eyeball and eyelid/ pupillary constriction and accommodation (parasympathetic)
  • Exists the skull via superior orbital fissure
301
Q
  • What is the name of CN4
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Trochlear
  • Motor
  • Superior oblique muscle
  • Depression, medial rotation and abduction of the eyeball
  • exists skull via the superior orbital fissure
302
Q
  • What is the name of CN5
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A

Trigeminal

  • sensory and motor
  • ophthalmic and maxillary division sensory, mandibular division both
  • Ophthalmic, maxillary and mandibular divisions sensory innervation of face, scalp, cornea, nasal and oral cavities
  • mandibular branch motor innovation of the muscles of mastication and salivary glands and tensor tympani muscle in the ear
  • V1 exists skull through the superior orbital fissure
  • V2 exits the skull via foramen rotundum
  • V3 exits the skull via the foramen ovale
303
Q
  • What is the name of CN6
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Abducens
  • motor
  • lateral rectus muscle
  • abduction of the eyeball
  • exits the skull through the superior orbital fissure
304
Q
  • What is the name of CN7
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • facial nerve
  • both and parasympathetic
  • sensory, anterior 2/3 tongue for taste
  • Motor, Muscles of facial expressions
  • Parasympathetic - Salivary and lacrimal secretions
  • exits the skull via the internal acoustic meatus
305
Q
  • What is the name of CN8
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • vestibulocochlear
  • sensory
  • vestibular apparatus
  • position and movement of head
  • exits the skull through the internal acoustic meatus
306
Q
  • What is the name of CN9
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • glossopharyngeal
  • both and parasympathetic
  • sensory - pharynx, posterior 1/3 of tongue taste and sensation, eustachian tube, middle ear, carotid body/sinus
  • motor, stylopharyngeus muscle for swallowing
  • parasympathetic - parotid gland for salivation
  • exits the skull via the jugular foramen
307
Q
  • What is the name of CN10
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Vagus
  • both and parasympathetic
  • sensory, pharynx, larynx, trachea and oesophagus, abdominal and thoracic viscera, aortic bodies and aortic arch
  • motor, soft palate, pharynx, larynx and oesophagus for speech and swallowing
  • parasympathetic - abdominal and thoracic viscera
  • exits the skull via the jugular foramen
308
Q
  • What is the name of CN11
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • spinal accessory
  • motor
  • sternocleidomastoid and trapezius muscles
  • movement of head and shoulders
  • exits the skull via the jugular foramen
309
Q
  • What is the name of CN12
  • Sensory, motor or both
  • structures innovated
  • function
  • where does it exit the skull?
A
  • Hypoglossal
  • motor
  • intrinsic and extrinsic muscles of the tongue
  • movement of the tongue
  • exits the skull via the hypoglossal canal
310
Q

What are the pluripotent stem cells that lie within the neural folds?

A

Neural crest cells.

311
Q

How is the neural tube formed?

A

Notochord in mesoderm signals the ectoderm to form a thickened neural plate. Mitosis forms a neural groove. There are neural folds either side of the groove. These fuse at the midline forming the neural tube.

312
Q

When should the neural tube fuse?

A

By the end of the 4th week.

313
Q

What vitamins are needed to ensure the neural tube fuses.

A

B9 (folic acid) and B12.

314
Q

What are the 3 primary vesicles?

A
  • Prosencephalon (forebrain).
  • Mesencephalon (midbrain).
  • Rhombencephalon (hindbrain).
315
Q

What are the sub-divisions of the prosencephalon?

A
  • Telencephalon.

- Diencephalon.

316
Q

What does the telencephalon form?

A
  • The cerebral hemispheres.
317
Q

What does the diencephalon form?

A
  • Thalamus.

- Hypothalamus.

318
Q

What does the mesencephalon form?

A
  • Midbrain.

- Colliculi.

319
Q

What are the sub-divisions of the rhombencephalon?

A
  • Metencephalon.

- Myelencephalon.

320
Q

What does the metencephalon form?

A
  • Cerebellum.

- Pons.

321
Q

What does the myelencephalon form?

A
  • Medulla oblongata.
322
Q

Where are the lateral ventricles formed in the embryo?

A

Telencephalon.

323
Q

Where is the 3rd ventricle formed in the embryo?

A

Diencephalon.

324
Q

Where is the 4th ventricle formed in the embryo?

A

Rhombencephalon.

325
Q

Give 3 functions of the cranial meninges.

A
  1. Protects the brain and spinal cord form injury.
  2. Provides a framework for cerebral and cranial vasculature.
  3. Provides a space for the flow of CSF.
326
Q

What are the 3 meningeal layers?

A
  1. Dura mater (outermost).
  2. Arachnoid mater.
  3. Pia mater (inner most).
327
Q

What are the 2 connective tissue sheets of dura mater?

A
  1. Endosteal layer - lines the cranium.

2. Meningeal layer.

328
Q

Where are the dural venous sinuses located?

A

Between the endosteal layer of dura and the meningeal layer.

329
Q

What vein do the dural venous sinuses drain into?

A

The internal jugular veins.

330
Q

Name 3 locations where the dura mater folds inwards as dural reflections?

A
  1. Falx cerebri.
  2. Tentorium cerebelli.
  3. Falx cerebelli.
331
Q

Where is the falx cerebri located?

A

It lies in the longitudinal fissure between the cerebral hemispheres.

332
Q

Where is the tentorium cerebelli located?

A

The tentorium cerebelli is a thick fibrous roof lying over the posterior cranial fossa and the cerebellum

333
Q

Where is the falx cerebelli located?

A

Between the 2 lobes of the cerebellum.

334
Q

What lies beneath the arachnoid mater?

A

The subarachnoid space containing CSF and arteries.

335
Q

What is the function of the blood-brain barrier?

A

It protects the brain by preventing the passage of some substances from the circulation into the nervous tissue.

336
Q

Which meningeal layers are highly vascularised?

A

The dura and pia mater. The arachnoid mater is avascular.

337
Q

What are the 2 main arteries that supply blood to the brain?

A
  1. Vertebral arteries.

2. Internal carotid arteries.

338
Q

Which arteries supply about 80% of blood to the brain?

A

The internal carotid arteries.

339
Q

What are the vertebral arteries a branch of?

A

The subclavian arteries.

340
Q

Where do the vertebral arteries enter the skull?

A

Through the foramen magnum.

341
Q

What are the internal carotid arteries branches of?

A

The common carotids. Arise from bifurcation at the same level as the upper border of the thyroid cartilage.

342
Q

What do the vertebral arteries supply?

A

The posterior cerebrum and the

contents of the posterior cranial fossa.

343
Q

What do the internal carotid arteries supply?

A

The anterior and middle parts of the cerebrum and the diencephalon.

344
Q

Where do the internal carotid arteries enter the skull?

A

Through the carotid foramina.

345
Q

What are the terminal branches of the internal carotid arteries?

A

The middle and anterior cerebral arteries.

346
Q

What does the middle cerebral artery supply?

A

The lateral surface of the hemispheres.

347
Q

What does the anterior cerebral artery supply?

A

The medial aspect of the hemispheres and the corpus callosum.

348
Q

What does the posterior cerebral artery supply?

A

The occipital lobe.

349
Q

What artery passes through foramen spinosum?

A

The middle meningeal artery.

350
Q

What do the two vertebral arteries form?

A

The basilar artery.

351
Q

Where is a berry aneurysm likely to occur?

A

At branching points in the circle of willis, especially at the anterior communicating artery.

352
Q

What is a berry aneurysm?

A

A sac-like out pouching that will progressively enlarge until it ruptures resulting in haemorrhage.

353
Q

What are the two types of stroke?

A
  1. Ischaemic.

2. Haemorrhagic (intracerebral or subarachnoid).

354
Q

Where do cerebral veins drain into?

A

Into dural venous sinuses.

355
Q

What does the great cerebral vein drain?

A

Deep brain structures.

356
Q

What sinus does the great cerebral vein drain into?

A

The straight sinus.

357
Q

Where is the straight sinus located?

A

In the midline of the tentorium cerebelli.

358
Q

What vessels lie in the cavernous sinus?

A
  • Cn 3, 4, 5(1), 5(2) and 6.

- Internal carotid artery.

359
Q

Why is the cavernous sinus of clinical importance?

A

If this sinus is infected Cn 3, 4, 5(1), 5(2) and 6 and the internal carotid artery could be affected.

360
Q

How do dural venous sinuses and veins outside the skull communicate?

A

Via emissary veins.

361
Q

Briefly describe the pathway of venous drainage starting at the great cerebral vein.

A

Great cerebral vein -> straight sinus -> transverse sinus -> sigmoid sinus -> internal jugular vein -> jugular vein -> brachiocephalic vein -> SVC.

362
Q

What sinuses form the confluence of sinuses?

A

The straight sinus and the superior sagittal sinus.

363
Q

Where is the largest aggregation of choroid plexus?

A

In the lateral ventricles.

364
Q

Where is the majority of CSF produced?

A

In the lateral ventricles (greatest amount of choroid plexus here`).

365
Q

What embryonic part of the brain is the midbrain formed from?

A

Mesencephalon.

366
Q

What embryonic part of the brain is the pons formed from?

A

Metencephalon of Rhombencephalon.

367
Q

What embryonic part of the brain is the medulla oblangata formed from?

A

Myelencephalon of Rhombencephalon.

368
Q

Where would you insert a lumbar puncture needle?

A

At the L3/L4 level in the sub-arachnoid space in order to take CSF.

369
Q

Where would you insert an epidural needle?

A

Between the dura mater and vertebrae in order to inject anaesthesia.

370
Q

Define dermatome.

A

An area of skin with a sensory nerve supply from a single root of the spinal cord.

371
Q

What is the dermatome for the thumb?

A

C6.

372
Q

What is the dermatome for the knee?

A

L3.

373
Q

What is the dermatome for the big toe?

A

L5.

374
Q

Where do the optic tracts terminate?

A

Lateral geniculate body in the thalamus.

375
Q

What is the function of the outer ear?

A

It gathers sound energy and focuses it on the tympanic membrane; this vibrates the tympanic membrane. The outer ear also amplifies sound.

376
Q

What are the 3 cavities of the cochlea?

A
  1. Scala vestibuli.
  2. Scala media.
  3. Scala tympani.
377
Q

Which of the cavities of the cochlea are filled with perilymph?

A

Scala vestibuli and scala tympani.

378
Q

What is the scala media filled with?

A

endolymph

379
Q

What does the organ of corti sit on?

A

The basilar membrane.

380
Q

Where are Cn 1 nuclei located?

A

Olfactory bulb.

381
Q

Where are Cn 2 nuclei located?

A

Lateral geniculate body.

382
Q

A man is feeling very distressed as he woke up being unable to feel the right side of his face and his right arm and leg. What lobe is affected?

A

The parietal lobe (somatosensory cortex). Feel is the key word here.

383
Q

A patient can understand what you’re saying but is unable to construct sentences in response. What part of the brain is affected?

A

Broca’s area in the dominant frontal lobe.

384
Q

A man presents to the stroke unit being unable to move/feel his right arm, right sided facial drooping and slurred speech. Which artery has been affected?

A

Left middle cerebral artery.

385
Q

A woman presents to the stroke unit with complete right sided visual field loss. Which artery has been affected?

A

Left posterior cerebral artery.

386
Q

A 40-year-old removal man felt immediate back pain and a popping sensation after lifting a heavy box. The next day he noticed he was tripping over his right foot as it was dragging along the floor. What is affected?

A

Lower motor neurones (he has a slipped disc. The LMN nerve roots coming out of the spinal cord have been damaged).

387
Q

An elderly patient presents with a stiff flexed arm, and a stiff extended leg (both on the left) which the patient finds difficult to bend. What is affected?

A

Upper motor neurone – this patient has had a stroke and so the UMN’s are affected.

388
Q

A 42-year-old female has presented with weakness in her left leg. She has been seen previously in your clinic two years ago for visual disturbance and sensory loss over the left forearm. These symptoms persisted for several weeks but then gradually resolved. Her symptoms are exacerbated following a shower. What is the problem?

A

Multiple Sclerosis (characterised by the fact it comes and goes. Exacerbated after a shower is also a key feature of this disease).

389
Q

A 30-year-old woman noticed that her face had become progressively droopier whilst putting her make-up on in the mornings. Weeks later she began to experience double vision, and found it progressively more tiring and difficult to chew all the food in her mouth when eating. What is the problem?

A

Myasthenia Gravis (characterised by progressive weakness and tiredness. Actions like chewing become much harder. It is a neuromuscular junction disease where the Ach receptors are blocked).

390
Q

A man has presented with a history of weakness in both of his hands, he is now unable to open jars. Both of his hands show wasting in the Thenar eminence. He has developed slurred speech and difficultly swallowing over the past 3 weeks. His tongue appears spastic and he is unable to protrude it. What is the disease?

A

Motor neurone disease - both UMN and LMN are affected.

391
Q

What is the only cranial nerve to emerge from the dorsal aspect of the brainstem?

A

Trochlear Cn 4.

392
Q

You are carrying out an eye examination on a patient who is looking at the tip of your nose. Behind you, on your left hand side, is a tall medical student. What would be the patients’ retinal representation of the image of this students’ face?

A

The retinal image is converted from right to left and reversed. The students face is now in left lower corner.

(Medical student is stood on your left but that is the patients right).

393
Q

In huntington’s disease what area of the basal ganglia and what neurotransmitter are affected?

A
  • Striatum (caudate nucleus).

- GABA.

394
Q

What site does brain stimulation affect?

A

Sub-thalamic nucleus.

395
Q

What neurotransmitter is in deficit in huntington’s disease?

A

GABA

396
Q

What is the visual pigment in the eye?

A

Rhodopsin.

397
Q

What nerve provides sensory innervation to the oropharynx?

A

Glossopharyngeal - Cn 9.

398
Q

What nerve provides sensory innervation to the laryngopharynx?

A

Vagus - Cn 10.

399
Q

What nerve provides sensory innervation to the nasopharynx?

A

Maxillary branch of the trigeminal - Cn 5(b).

400
Q

Which part of the brain has a role in addiction?

A

The insular cortex.

401
Q

Mutation of what protein can result in duchenne?

A

Dystrophin.

402
Q

What is the function of dystrophin?

A

It provides structural stability to muscle cell membranes.

403
Q

Which cranial nerve can be tested in the unconscious patient by observing pupillary constriction in response to light?

A

Optic - CN2.

404
Q

What is the entry/exit foramina for the ophthalmic artery?

A

Optic canal.

405
Q

What is the entry/exit foramina for the superior ophthalmic vein?

A

Superior orbital fissure.

406
Q

What is the entry/exit foramina for the labyrinthine artery?

A

Internal acoustic meatus.

Phase 1 Med (7 decks)

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