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Phase 1 > Neuroscience > Flashcards

Neuroscience Flashcards

1
Q

What are the developmental milestones in development?

A
  • By 3 weeks there is eye formation
  • 10 weeks = cerebral expansion + commissures
  • 3 months = basic structures established
  • 5 months = myelination has begun
  • 7 months = lobes cerebrum has formed
  • 9 months = gyri + sulci formed
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2
Q

What are some critical periods in development?

A
  • Abnormalities to CNS are dependent on time of infection
  • 6th week = eye malformations occur, e.g. cataracts
  • 9th week = deafness can occur, e.g. malformation of the organ of Corti
  • 5th to 10th week = cardiac malformation occurs
  • In general, CNS disorders occur in the 2nd trimester
  • Risk of disorders falls after 16 weeks due to the fact that most of the structures of the CNS have developed by this time
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3
Q

How can increases in neural activity be detected by a lumbar puncture?

A
  • Increases in neural activity results in the increase in the release of neurotransmitters + their associated breakdown products, this can be detected in the CSF by lumbar puncture
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4
Q

What do more neurally active regions require?

A
  • More neurally active regions require more O2 + thus more blood, this is the basis of modern imaging techniques as they detect haemodynamic changes
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5
Q

What does an EEG give an indication of?

A
  • EEG gives an indication of regional brain activity underlying electrodes
  • Sensitive to activity in the temporal regions but less sensitive to those in the spatial regions
  • EEG is good at detecting signs of epilepsy
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6
Q

What are the two types of muscle fibres?

A
  • Slow twitch
  • Fast twitch, 2a = glycolytic and oxidative (intermediate), 2b = glycolytic (white)
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7
Q

What is a motor unit?

A
  • A motor unit is made up of a motor neuron + skeletal muscle fibres innervated by that motor neuron’s axonal terminals
  • Groups of motor units often work together to coordinate the contractions of a single muscle
  • Loss of innervation causes fibre atrophy
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8
Q

What are mitochondrial cytopathies?

A
  • Mitochondrial cytopathies = heterogenous group of multisystem disorders which preferentially affect the muscle + nervous systems
  • They are either caused by mutations in the maternally inherited mitochondrial genome, or by nuclear DNA mutations
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9
Q

What are dystrophies?

A
  • Dystrophies are genetically determined, destructive + mainly progressive disorders of muscle
  • Many types, defects of proteins that confer stability to the sarcolemma are one group of causes
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10
Q

Membrane stain of dystrophin.

A
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11
Q

What are the 3 layers of the eye? What do they contain?

A
  • Fibrous (outer) layer = cornea + sclera
  • Vascular (middle) layer = iris, ciliary body and choroid
  • Inner layer (retina)
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12
Q

What is the humour called in the anterior and posterior chamber? How about the rest of the eye?

A
  • Anterior and posterior chamber = aqueous humour (thin, transparent fluid, 99.9% water)
  • Rest of the eye = vitreous humour (clear gel)
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13
Q

What is the fibrous layer comprised of? What do these do?

A
  • Made up of cornea + sclera
  • Sclera = tough fibrous outer coat, made of collagen, 85% of layer
  • Cornea = made of collagen, part of fibrous layer over pupil + iris so transparent
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14
Q

What is the vascular layer comprised of? What do these do?

A
  • Vascular layer comprised of choroid, ciliary body (ciliary muscle + ciliary processes) and iris
  • Iris = coloured part of the eye. Controls the size of the pupil through dilator and sphincter papillae muscles
  • Ciliary body (ciliary muscle + ciliary processes) = controls size of lens and forms aqueous humour
  • Choroid = connective tissue + blood vessels, blood supply to outer third of retina
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15
Q

When the ciliary muscles contract, what happens?

A

Ciliary muscle contracts, suspensory ligaments relax, this relaxes tension on lens + lens becomes more rounded

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16
Q

What do the sphincter papillae and dilator papillae do? What are these innervated by?

A
  • Sphincter papillae = constricts the pupil = PARASYMPATHETIC (oculomotor CN)
  • Dilator papillae = dilates the pupil = SYMPATHETIC
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17
Q

What is in the inner layer?

A
  • Retina
  • Two parts: optic part (light sensitive) + nonvisual part (covers internal surface of ciliary body and iris)
  • There are many layers to the retina
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18
Q

What are the layers of the retina? What is found within them?

A
  • Pigmented layer
  • Neural layer:
  • Photoreceptors. RODS = function in dim light + are insensitive to colour. CONES = respond to bright light and sensitive to colour
  • Bipolar cells
  • Ganglion cells = synapse in the lateral geniculate body
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19
Q

What are the layers through which a photon must travel through the eye?

A
  • Tear film (3 layers: anterior lipid, middle aqueous and posterior mucous)
  • Cornea (transmission + refraction)
  • Aqueous humour
  • Lens
  • Vitreous humour
  • Ganglion cell
  • Amacrine cell
  • Bipolar cell
  • Horizontal cell
  • Cone
  • Rod
  • Pigmented epithelium (absorption of excess photons)
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20
Q

What are the two main different cell types in the CNS?

A
  • Neurons
  • Glial cells (provide support + protection for neurons = glue)
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21
Q

What are some different types of glial cells?

A
  • Oligodendrocytes
  • Microglia
  • Astrocytes
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22
Q

Picture of a neuron.

A
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23
Q

What are neurons used for? Where do they mainly develop?

A
  • Specialised for intercellular electrical signalling via synapses
  • Dendrites receives inputs (dendritic spines), transmit to cell body (soma)
  • Action potentials propagate along axon
  • Mainly develop during brain development
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24
Q

Neurons communicate via synapses. What are the two types?

A
  • Chemical (majority)
  • Electrical (less abundant, enable synchronised electrical activity)
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25
Q

What are oligodendrocytes?

A
  • Myelinating cells of the CNS
  • Myelin insulates axon segments, allows rapid conduction
  • Myelin sheath interrupted by nodes of Ranvier = saltatory conduction
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26
Q

How are oligodendrocytes different from Schwann cells?

A
  • Schwann cells = PNS, oligodendrocytes = CNS
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27
Q

What are microglia?

A
  • Resident immune cells of CNS
  • Upon activation, become amoeboid + mobile
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28
Q

What are astrocytes? What are the 3 types?

A
  • Most numerous cells in the CNS
  • 3 types = radial glia, Bergmann glia + Müller cells
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29
Q

What are the two forms of astrocytes?

A
  • Fibrous = white matter, contact blood vessels, pia + nodes of Ranvier
  • Protoplasmic = grey matter, contact blood vessels + pia
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30
Q

What are the functions of astrocytes?

A
  • Contribute to blood-brain barrier
  • Structural - define brain micro-architecture
  • Envelop synapses
  • Homeostatic
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31
Q

In the CNS, what do these terms mean:

  • tracts
  • commissures
  • grey matter
  • white matter
A
  • tracts = what axons gather into
  • commissures = tracts that cross midline
  • grey matter = abundant into neurone cell bodies + processes
  • white matter = contains abundance of myelinated tracts + commissures
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32
Q

In the PNS, where are cell bodies located? What are axons bundled into?

A
  • Cell bodies and supporting cells located in ganglia, e.g. dorsal root ganglia
  • Axons bundled into nerves
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33
Q

What are the features of the blood-brain barrier?

A
  • Endothelial tight junctions
  • Astrocytes end feet
  • Pericytes
  • Continuous basement membrane, lacks fenestrations
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34
Q

What are ependymal cells?

A
  • Epithelial-like, line ventricles + central canal of spinal cord
  • CSF production, flow + absorption
  • Ciliated - facilitates flow
  • Allow solute exchange between nervous tissue + CSF
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35
Q

What is the choroid plexus?

A
  • Frond-like projections in ventricles
  • Formed from modified ependymal cells, villi form around large network of capillaries - highly vascularised + large surface area
  • Main site CSF production by plasma filtration
  • Gap junctions between cells form blood-CSF barrier
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36
Q

What is the structure of a neuron?

A
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37
Q

What are the two connections between neurons?

A
  • Transmission of information from location A to location B = axonal transmission
  • Integration/processing of information and transmission between neurons = synaptic transmission
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38
Q

What are the 3 types of synapses? What are the two types of synaptic transmission?

A
  • Excitatory, e.g. acetylcholine
  • Inhibitory, e.g. GABA
  • Modulatory
  • 2 types of synaptic transmission = chemical (majority) + electrical
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39
Q

What determines the resting potential in a neuron (-70mV)?

A
  • Na+/K+ pump, 3Na+ out for 2K+ in, active process
  • K+/Cl- can move backward + forward across membrane so reach a steady state by opposing forces of diffusion and electrostatic attraction
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40
Q

What causes the action potential?

A
  • Neurotransmitters activate receptors on dendrites/soma, receptors open ion channels + ions cross plasma membrane, changing membrane potential
  • If the membrane potential reaches threshold, voltage-gates Na+ channels open + Na+ ions flow in
  • Membrane potential reaches +30mV, at which point the voltage-gated Na+ channels close + the voltage-gated K+ channels open. More potassium outside cell, so more K+ exits than enters. This restores the membrane potential
  • Hyperpolarisation: K+ channels stay open a little bit longer, so the cell temporarily hyperpolarises. K+ channels then close, Na+/K+ pump restores resting membrane potential
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41
Q

What is propagation?

A

The generation of an action potential at a segment causes depolarisation of adjacent membrane leading to a current of flow

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42
Q

What speeds up the action potential?

A
  • Greater diameter axon = faster action potential (less resistance)
  • Myelination = faster action potential (less leakage) = saltatory conduction
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43
Q

What happens when the action potential reaches the pre-synaptic axon terminal?

A
  • Action potential reaches pre-synaptic axon terminal
  • Voltage-gates Ca2+ channels open
  • Ca2+ enters axon terminal
  • Neurotransmitter is released + diffuses into the cleft
  • Neurotransmitter binds to postsynaptic receptors. These may be excitatory or inhibitory
  • Neurotransmitter removed from synaptic cleft
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44
Q

What is temporal and spatial summation?

A
  • One synaptic neurone may not be enough to reach threshold in the postsynaptic neurone
  • Temporal - input signal arrives from the same presynaptic at DIFFERENT TIMES
  • Spatial = two inputs from two different locations
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45
Q

What are the pros and cons of CT scanning?

A
  • Pros: better than MRI for demonstrating bone + calcification, quicker scan times than mRI
  • Cons: Dose of radiation high (1 CT = 100 chest x-rays), limited anatomical detail, requires iodinated contrast media (potential for allergic reaction)
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46
Q

What are the pros and cons of mRI scanning?

A
  • Pros: no ionising radiation, multiple planes possible, excellent anatomical detail
  • Cons: contrast injection may be required, strong magnetic field, noisy + claustrophobic, longer scan times than CT
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47
Q

When does gastrulation occur? What do the 3 layers go on to become?

A
  • Gastrulation = 3rd week of development
  • Ectoderm = skin, nervous system
  • Mesoderm = Notochord, muscular system
  • Endoderm = epithelial lining of gut + respiratory system, liver, pancreas
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48
Q

The ectoderm thickens in the midline to form what?

A

Neural plate

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49
Q

What lies lateral to the neural groove? What do these form?

A

The presumptive neural crest cells. They form:

  • melanocytes, Schwann cells, neurons
  • osteoblasts, osteocytes, adipocytes, chondrocytes
  • sensory dorsal root ganglia of spinal cord + CN V/VII/IX/X, adrenal medulla, bony skull, meninges
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50
Q

What are some abnormailities of the spinal cord?

A
  • The neural tube usually closes at the end of the 4th embryonic week
  • Anencephaly = failure to close cephalic region
  • Failure to close spinal region = spina bifida
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51
Q

What are the three primary brain vesicles at 3-4 weeks?

A
  • Prosencephalon (forebrain)
  • Mesencephalon (midbrain)
  • Rhombencephalon (hindbrain)
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52
Q

By 5 weeks, the three primary brain vesicles have developed into 5 secondary brain vesicles. What are these?

A
  • Prosencephalon —> telencephalon + diencephalon
  • Mesencephalon —> mesencephalon
  • Rhombencephalon —> metencephalon + myelencephalon
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53
Q

What do the five secondary brain vesicles develop into?

A
  • Telencephalon —> cerebrum
  • Diencephalon —> thalamus, hypothalamus, epithalamus
  • Mesencephalon —> midbrain
  • Metencephalon —> pons, cerebellum
  • Myelencephalon —> medulla oblangata
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54
Q

What are the 3 parts of the ear?

A
  • External ear
  • Middle ear
  • Internal ear
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55
Q

What is the function of the pinna? What is it made out of?

A
  • Pinna directs sound waves towards ear canal
  • Pinna is a cartilagenous structure formed from pharyngeal arches 1 + 2 (6x hillocks of His)
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56
Q

What are the bones, muscles, tubes and windows of the middle ear?

A
  • Bones: malleus, incus + stapes
  • Muscles: tensor tympani + stapedius
  • Tube: Eustachian tube
  • Windows: oval window + round window
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57
Q

What is the role of the middle ear?

A

Amplification, it transmits vibrations from the tympanic membrane to the inner ear via auditory ossicles (MIS)

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58
Q

What are the roles of the middle ear muscles?

A
  • Protection from trauma
  • Stiffens the ossicular chain during the acoustic reflex of the stapedius muscle. This happens with high-intensity sounds
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59
Q

What is the role of the ear bones?

A
  • Carry vibration from the tympanic membrane
  • Malleus gathers sound from the tympanic membrane
  • Stapes directs it into the inner ear via the oval window
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60
Q

What is the role of the Eustachian tube?

A
  • Equalises air pressure by opening
  • Removes secretion
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61
Q

What is the vestibulocochlear apparatus? What does it contain? What is it innervated by?

A
  • A set of fluid filled sacs, encased in bone
  • Cochlear = responsible for hearing
  • Labyrinth = responsible for balance
  • Innervation = vestibulocochlear nerve
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62
Q

What are the two cochlear fluids?

A
  • Perilymph = Na+ rich, like CSF
  • Endolymph = high K+
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63
Q

What is the bony labyrinth?

A
  • Contains perilymph
  • Consists of:
  • cochlea
  • vestibule
  • semicircular canals (lateral, superior + posterior)

Image shows vestibular system

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64
Q

What is the membranaceus labyrinth? What does it contain? Where does it lie?

A
  • Contains endolymph
  • Lies within bony labyrinth
  • Consists of:
  • cochlear duct
  • utricle
  • saccule
  • semicircular ducts (lateral, superior + posterior)
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65
Q

What is the cochlea? What are its two openings? What are its three compartments?

A
  • Fluid filled bony tube
  • 2 openings = round window + oval window
  • 3 compartments = scala vestibuli, scala media + scala tympani
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66
Q

Picture of inner ear.

A
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67
Q

Picture of cochlea.

A
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68
Q

How is sound transmitted in the external ear?

A
  • Sound enters into the auricle
  • Transmits through the external acoustic meatus
  • Sound causes vibration of the tympanic membrane (eardrum) which transmits to middle ear
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69
Q

How is sound transmitted in the middle ear?

A
  • Pressure of middle ear is equal to the atmospheric pressure (Eustachian tube)
  • Vibrations of the tympanic membrane are transmitted to the middle ear through the ossicles (MIS)
  • This goes through the oval window to the fluid-filled cochlea
  • Muscles = tensor tympani + stapedius
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70
Q

How is sound transmitted in the inner ear (cochlea)?

A
  • Vibrations of the stapes at the oval window create pressure waves in the perilymph
  • Waves move through the helicotrema into scala tympani
  • Wave motion transmitted to endolymph
  • Basilar membrane vibrates
  • Hair cells on the organ of Corti act as mechanoreceptors, activates the organ of Corti
  • Bending of the stereocilia on organ of Corti causes an influx of K+, which results in Ca2+ influx (from depolarisation), this results in the release of neurotransmitter
  • This illustrates how a soundwave is turned into a neurological impulse
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71
Q

What is the organ of Corti? What do the hair cells do?

A
  • Organ of Corti = spiral organ
  • Hair cells translate endolymph movement into nerve impulse
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72
Q

How does the soundwave get to the brain?

A
  • Central auditory pathway (remember ECOLIMA):
  • Ear receptors + eight CN
  • Cochlear nucleus
  • Superior olivary nucleus
  • Lateral lemniscus
  • Inferior colliculus
  • Medial geniculate body
  • Auditory complex (temporal lobe)
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73
Q

In the vestibular system, what are the roles of the utricle, saccule and semi-circular ducts?

A
  • Utricle = horizontal movement
  • Saccule = vertical movement
  • Semi-circular ducts = head movements: nodding, shaking, tilting
  • All DETECT. Think of these as a spirit level, e.g. your head moves around, liquid inside semicircular canals sloshes around and moves hairs, they then send a signal
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74
Q

How do the semicircular canals detect rotation?

A
  • Hair cells detect endolymph movement
  • Signal sent via vestibular nerve
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75
Q

How do the otoliths organs detect movement?

A
  • Otolith organs = saccule and utricle
  • Crystals in the endolymph move on acceleration
  • Hair cells detect the crystals
  • Signal sent via vestibular nerve
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76
Q

What is a nerve conduction study (NCS) to test sensory function?

A
  • Electrical stimulation makes outside of nerve negative
  • Inside is positive, so action potential triggered
  • Electrodes record size + speed of action potential
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77
Q

What is a nerve conduction study (NCS) to study motor function?

A
  • Electrical stimulation induces an action potential
  • AP reaches neuromuscular junction causing ACh release
  • ACh activates AChRs on the muscle and causes muscle to contract (you see a visible twitch)
  • Measure size of response + speed
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78
Q

What is electromyography?

A
  • Uses a needle to pick up electrical activity from muscle
  • Records activity of individual muscle units
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79
Q

What is electroencephalograph (EEG)?

A
  • Primarily done for patients with seizures
  • Electrodes placed in specific locations on the scalp
  • Ask patient to do various things during the recording, e.g. close eyes, hyperventilate
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80
Q

What are the three types of evoked potentials? What do they measure?

A
  • Somatosensory evoked potentials (sensory pathways) = look at integrity of dorsal columns, stimulate peripheral nerve + response from somatosensory cortex using scalp electrodes
  • Visual evoked potentials (visual pathways) = flash checkboard patterns whilst recording over visual cortex with EEG electrodes
  • Transcranial magnetic stimulation (motor pathways) = place magnet over motor cortex and record from contralateral muscle, a brief magnetic pulse induces an electric current that excites cells in the motor cortex, these fire down the motor pathway, you can record a response from a limb muscle
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81
Q

In what format is the image on the retina? Why?

A
  • Image on retina is inverted and upside down
  • This is because the cornea refracts light
  • The brain eventually turns the image the right way up
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82
Q

How many neurons does the visual pathway consist of?

A

3 neurons - bipolar cells, ganglion cells + neurons from lateral geniculate nucleus

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83
Q

Where is the primary visual cortex found?

A

In the occipital lobe, around the calcarine sulcus

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84
Q

This gives the primary visual cortex its striped appearance. What is it called?

A

Stria of Gennari

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85
Q

Where does the light sensitive photopigment on rod and cone cells lie?

A

In discs on the outer segment

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86
Q

What happens when light reaches the retina?

A
  • Hits the photoreceptors (rod and cone cells)
  • Photopigment absorbs specific wavelength of light, e.g. rhodopsin
  • Photopigment transducer photons of energy from light into neurotransmitter release –> activates electrical activity in bipolar neurons –> ganglion cells
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87
Q

What is the pathway of light from the eye to the brain?

A
  • Visual field
  • Visual field representation on the retina
  • Photoreceptors
  • Bipolar cells
  • Ganglion cells
  • Optic nerve
  • Optic chiasma
  • Optic tract
  • Lateral geniculate body
  • Meyer’s loop/Baum’s loop
  • Primary visual cortex
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88
Q

Another diagram of the visual pathway.

A
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89
Q

What would these lesions cause?

A
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90
Q

What are the twelve cranial nerves?

A

(Remeber: On Occasion Our Trusty Truck Acts Funny Very Good Vehicle Any How)

  • 1: Olfactory
  • 2: Optic
  • 3: Oculomotor
  • 4: Trochlear
  • 5: Trigeminal
  • 6: Abducens
  • 7: Facial
  • 8: Vestibulocochlear
  • 9: Glossopharyngeal
  • 10: Vagus
  • 11: Accessory
  • 12: Hypoglossal
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91
Q

What are the sensory and motor functions of the cranial nerves?

A

(Remember: Some Say Money Matters But My Brother Says Big Brains Matter More)

  • 1: Olfactory = sensory
  • 2: Optic = sensory
  • 3: Occulomotor = motor
  • 4: Trochlear = motor
  • 5: Trigeminal = both
  • 6: Abducens = motor
  • 7: Facial = both
  • 8: Vestibulocochlear = sensory
  • 9: Glossopharyngeal = both
  • 10: Vagus = both
  • 11: Accessory = motor
  • 12: Hypoglossal = motor
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92
Q

Where do the twelve cranial nerves emerge from?

A
  • First two (olfactory + optic) emerge from cerebrum
  • Remaining ten emerge from the brainstem (CN IX, X, XI and XII emerge from the medulla oblangata)
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93
Q

What would happen if there was damage to:

a) left optic nerve
b) optic chiasma
c) left optic tract
d) left Meyer’s loop
e) left Baum’s loop

A

a) no vision through left eye
b) loos of vision of temporal visual fields
c) loss of vision in temporal field of left eye + loss to nasal field of right eye
d) loss of vision in superior nasal field of left eye + superior temporal field of right eye
e) loss of vision in inferior nasal field of left eye + superior temporal field of right eye

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94
Q

What are the four autonomic (parasympathetic) cranial nerves?

A
  • Remeber 1973 (10, 9, 7 and 3)
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95
Q

What are the two anatomical divisions of the nervous system? Which one are the cranial nerves part of?

A
  • CNS and PNS
  • Cranial nerves = PNS and arise from the brain, spinal nerves arise from the spinal cord
96
Q

What types of information do cranial nerves carry?

A
  • Motor (somatic, branchial + autonomic)
  • Sensory (somatic, special + autonomic)
97
Q

What is the function of each cranial nerve?

A
  • Olfactory (1) = smell (sensory)
  • Optic (2) = vision (sensory)
  • Occulomotor (3) = eye movements, sympathetic = pupil dilation, parasympathetic = pupil constriction, accommodation (motor)
  • Trochlear (4) = SO4 LR6, all other muscles are innervated by CN 3
  • Trigeminal (5) = sensory = anterior 2/3 tongue, face, motor = jaw movement, three branches (motor)
  • Abducens (6) = lateral rectus (motor)
  • Facial (7) = motor = facial expressions, lacrimal/salivary/sublingual, sensory = taste bud anterior 2/3 tongue (both)
  • Vestibulocochlear (8) = hearing and balance (sensory)
  • Glossopharyngeal and Vagus (9 and 10) = motor = swallowing and gag reflex, sensory = posterior 1/3 of tongue, secretion of parotid gland (both)
  • Accessory (11) = sternocleidomastoid and trapezius (motor)
  • Hypoglossal (12) = tongue movement (motor)
98
Q

What is the innervation of the tongue?

A
  • Motor = hypoglossal (XII) except palatoglossus, pharyngeal branch of vagus (X)
  • Posterior 1/3 = sensory and taste = glossopharyngeal (IX)
  • Anterior 2/3 = sensory = lingual branch of V3 from trigeminal (V), taste = chorda tympani branch of facial (VII), carried by lingual branch
99
Q

Which cranial nerves pass through the cavernous sinus?

A
  • Remember O TOM CAT (trochlear twice to make mnemonic work)
  • Oculomotor, Trochlear, Opthalmic trigeminal, Maxillary trigeminal, Carotid (internal), Abducens, Trochlear
100
Q

In the PNS, are afferent fibres motor or sensory?

A
  • Peripheral nerves can contain nerve fibres that are the axons of efferent neurones (motor), afferent neurones (sensory) or both
  • All spinal nerves contain efferent + afferent, cranial nerves are efferent, afferent or both
101
Q

What is pain? What is acute and chronic pain?

A
  • Pain = an unpleasant sensory + emotional experience associated with actual potential tissue damage, or described in terms of such damage
  • Acute pain = short term pain <12 weeks, chronic pain = pain >12 weeks
102
Q

What is nociceptive and neuropathic pain?

A
  • Nociceptive pain = pain arising from damage to non-neural tissue, due to activation of nociceptors
  • Neuropathic pain = pain from primary lesion/dysfunction of nervous system, e.g. spinal nerve root compression
103
Q

What are nociceptors?

A

Sensory neurons that can sense pain (found on end of some first-order neurons)

104
Q

What are the three receptors between the sensory receptor in the periphery and the perception of sensation at the level of the cerebral cortex?

A
  • First-order neurons (primary afferent neurons) = enters spinal cord through spinal nerve, transmit info to dorsal root ganglion to synapse with a second-order neuron
  • Second-order neurons = axons decussate to other side of CNS as either lateral spinothalmic tract (pain and temperature) or anterior spinothalmic tract (crude touch). Ascends to thalamus where it terminates
  • Third-order neurons = cell body located in thalamus + axon projects to somatosensory cortex in post central gyrus of parietal lobe —> perception of pain
105
Q

What is the difference between alpha-delta fibres and C fibres?

106
Q

Describe the pain pathway.

A
  • Nociceptors (on a-delta + C fibres) synapse with second order neurons in dorsal horn of spinal cord
  • A-delta (first order neuron) terminals release glutamate as their neurotransmitters, C fibres release glutamate + substance P (slow acting)
  • Second order neurons transmit pain impulse up either the spinothalmic tract (lateral + anterior) or the trigeminal-thalamic tract, both of these terminate at thalamus
  • Third order neurons ascend from thalamus to terminate in somatosensory cortex on post central gyrus of parietal lobe
107
Q

What are the roles of the insula and cingulate gyrus in response to pain?

A
  • Insula = where degree of pain is judged
  • Cingulate gyrus = involved in emotional response to pain
108
Q

What is the role of the periaqueductal grey in pain response?

A
  • Grey matter in cerebral aqueduct, receives info from spinothalmic tract
  • Once activated, opioid receptors are activated resulting in reduction of pre-synaptic neuronal activity, so reduces substance P release which reduces pain sensation
109
Q

What is analgesia? What is anaesthesia? What is the Melzack-Wall pain gate?

A
  • Analgesia = selective suppression of pain without affecting consciousness or sensation. Centrally acting = decreased perception, locally acting = decreased chemical production
  • Anaesthesia = uniform suppression of pain, sometime consciousness is lost, e.g. general anaesthesia
  • Melzack-Wall pain gate = non-painful input closes the gate to painful input, so prevents pain travelling to somatosensory cortex to be perceived + thus felt, e.g. rubbing a painful area reduces pain
110
Q

A 30 year old woman noticed both her eye lids becoming progressively more droopy with time (ptosis). Weeks later she began to experience double vision, and found it progressively more tiring and difficult to chew while eating. Which of these is the likely cause?

Motor neurone disease

Myasthenia gravis

Multiple sclerosis

Spinal cord compression

Stroke/TIA

A

Myasthenia Gravis
• Condition of the neuromuscular junction
• Acetylcholine receptors are blocked by an auto immune reaction between the receptor protein and anti-acetylcholine receptor antibody.
• Women more affected than men. Presents between 15 to 50 years.
• Main symptom is abnormal fatigable weakness of muscles.
• First symptoms are usually ptosis or diplopia.
• Weakness of chewing, swallowing, speaking or limb movement can occur.

111
Q

89-year-old right-handed man presents with acute onset of weakness and numbness of his left lower leg and foot is unusually agitated and in an aggressive mood. Which artery is likely to have been affected?

Anterior cerebral artery

Posterior cerebral artery

Basilar artery

Middle cerebral artery

External carotid artery

A

Anterior cerebral artery
• Supplies the anteromedial surface of the cerebral hemisphere.
• Paraplegia usually affects the lower limbs sparing the upper limbs and face.
• They may be incontinent.
• They may display frontal lobe symptoms e.g. personality changes

112
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. Where is the cause most likely to be located?

Upper motor neurone

Muscle

Nerve root

Neuromuscular junction

Peripheral nerve

A

Nerve root.

  • This is a case of foot drop
  • It is caused by paralysis of the muscles that lift the foot
  • Given the history the most likely cause of damage is compression of the nerve root by a prolapsed vertebral disc.
113
Q

Which of these supplies the circle of Willis?

Internal carotid artery

Middle cerebral artery

Labyrinthine artery

Anterior spinal artery

Pontine artery

A

Internal carotid artery

114
Q

You are clerking an elderly gentleman who has had a stroke; the patient keeps trying to take his gown off and some of his responses are inappropriate and occasionally rude. Where is the likely lesion?

Cerebellum

Brainstem

Frontal lobe

Occipital lobe

Parietal lobe

A

Frontal lobe lesions may have the following characteristics
• Decreased lack of spontaneous activity - no desire to do anything and is unable to plan activities.
• Loss of attention - lack of interest and is easily distracted.
• Memory is normal but the patient cannot be bothered to remember.
• Loss of abstract thought - eg, cannot understand proverbs.
• Perseveration - a tendency to continue with one form of behaviour when a situation requires it to change.
• Change of affect - the patient either becomes apathetic and ‘flat’ or becomes over-exuberant and childish or uninhibited with possibly inappropriate sexual behaviour.

115
Q

A 51 year old man has a 2 month history of weakness in both of his hands, he is now unable to open jars. His hands show wasting of the thenar eminence. He has recently developed slurred speech and difficulty swallowing. His tongue appears spastic and he is unable to protrude it. Which of these is the likely cause?

Motor neurone disease

Multiple sclerosis

Stroke/TIA

Myasthenia gravis

Spinal cord compression

A

Motor Neurone Disease
• Progressive disorder of unknown aetiology
• Onset usually after age 50. Males more likely to be affected.
• Present with combination of both UMN and LMN signs without sensory involvement.
• Symptoms include – limb weakness, cramps, disturbance of speech or swallowing.
• Signs – wasting and fasciculation of muscles, pyramidal tract involvement causing spasticity and exaggerated tendon reflexes
• Symptoms can start focally but become widespread with time

116
Q

53 year old hypertensive man with sudden collapse; unable to move any part of his body except for eye movements, he appears to understand your questions, but is unable to answer. Where is the likely lesion?

Parietal lobe

Frontal lobe

Occipital lobe

Cerebellum

Brainstem

A

Brainstem lesions
• This is locked-in syndrome.
• Patients cannot move or communicate verbally due to paralysis of nearly all voluntary muscles.
• Blinking and vertical gaze may be preserved depending on the extent and level of the lesion within the brainstem
• They are conscious and aware.
• Complete recovery is rare.

117
Q

Whilst examining an elderly lady who arrives on the stroke ward, it becomes apparent that she can only see one half of your face. Where is the likely lesion?

Frontal lobe

Brainstem

Parietal lobe

Occipital lobe

Cerebellum

A

Occipital lobe lesions
• Typically cause visual disturbances and depends on where the lesion is
• These can include visual illusions and hallucinations
• Trouble recognising objects or facial blindness
• Being able to write but not read
• When a lesion affects most of the occipital lobe on one side it can cause an homonymous hemianopia which means the patient is unable to see the visual field on the opposite side of the lesion

118
Q

A 30 year old pregnant lady complains to the GP of progressive hand weakness. She is unable to open jars and even grip her tea cup. The GP noticed that the muscles around her thumb were wasting. Where is the cause most likely to be located?

Nerve root

Peripheral nerve

Muscle

Upper motor neurone

Neuromuscular junction

A

Carpal tunnel syndrome
• This due to compression of the median nerve in the carpal tunnel.
• Wasting of the abductor pollicis brevis can develop with the following distribution of numbness and pain.

119
Q

An elderly patient with a stiff flexed arm, and a stiff extended leg (both on the left) which the patient finds difficult to bend. Where is the cause most likely to be located?

Muscle

Peripheral nerve

Nerve root

Upper motor neurone

Neuromuscular junction

A

Upper motor neuron

120
Q

The patient walks with a wide unsteady gait and appears uncoordinated. Their speech is slurred. Where is the likely lesion?

Brainstem

Occipital lobe

Cerebellum

Frontal lobe

Parietal lobe

A

Cerebellar lesions
• Patients have a wide unsteady gait
• Impaired coordination
• Uncontrolled repetitive eye movements
• Difficulty with fine motor tasks
• Intentional Tremor
• Slurred speech

121
Q

42 year old female suffers a violent headache followed by sudden collapse. You notice that her left pupil is fixed and dilated and her left eye is deviated laterally and downwards. Which artery is likely to have been affected?

Middle cerebral artery

Anterior communicating artery

Posterior communicating artery

Basilar artery

External carotid artery

A

Posterior communicating artery
• This is most likely due to rupture of a posterior communicating aneurysm leading to a sub arachnoid haemorrhage.
• This has caused an ipsilateral third nerve palsy causing her pupil to dilate and the eye to deviate laterally and downwards.
• Paralysis of the third cranial nerve affects the medial, superior, and inferior recti, and inferior oblique muscles.
• The eye is incapable of movement upwards, downwards or inwards, and at rest the eye looks laterally and downwards owing to the overriding influence of the lateral rectus and superior oblique muscles respectively.

122
Q

A 69 year old lady was slurring her words at a church coffee morning. At the same time her right arm began to feel heavy and weak. 24 hours later all her symptoms had resolved. Which of these is the likely cause?

Spinal cord compression

Stroke/TIA

Multiple sclerosis

Motor neurone disease

Myasthenia gravis

A

Stroke/TIA.

  • Acute stroke is characterised by sudden onset of focal neurological deficit e.g. hemiplegia
  • Can be ischaemic or haemorrhagic
  • If function recovers within 24 hours then it is termed a transient ischaemic attack (TIA)
123
Q

What are the two main functions of the limbic system?

A
  • Instinctive and emotional aspects of behaviour
  • Memory
  • Influences endocrine system + autonomic nervous system via hypothalamus
124
Q

What are the cortical structures of the limbic system?

A
  • Hippocampus = long-term memory
  • Cingulate gyrus = neuropathic pain, nociception
  • Parahippocampal gyrus
  • Fornix
125
Q

What are the subcortical structures of the limbic system?

A
  • Amygdala = emotional memory, fear responses
  • Nucleus accumbens = desires, cravings, addiction
  • Hypothalamus = output of limbic system through endocrine system + has extensive connections in the brain. Damage to hypothalamus disrupts homeostasis + drive-related behaviours
  • Olfactory bulb = smell, its relation to memory
126
Q

How are the various components of the limbic system connected?

A

Papez circuit = part of limbic system responsible for memory processing

127
Q

Label this diagram of the limbic system.

128
Q

What are the parts of the limbic system involved in memory? What are the different types of memory?

A
  • Hippocampus = removal results in inability to lay down new memories
  • Mamillary bodies involved in formation of new memories
  • Episodic = hippocampus + midbrain
  • Semantic = frontal temporal lobe
  • Implicit memory (driving a car):
  • Skills/habits = cerebellum + basal ganglia
  • Conditioned reflexes = cerebellum + others
  • Emotional = amygdala
129
Q

Venous drainage of the blood question.

130
Q

Arterial supply of the brain question.

131
Q

Circle of Willis question.

132
Q

Stroke syndromes and functional units of the brain question

133
Q

Primary motor cortex question.

134
Q

Primary motor cortex question.

135
Q

Descending pathways question.

136
Q

Corticospinal tract question.

137
Q

Descending tract question.

138
Q

Muscle spindle question.

139
Q

Muscle spindle question.

140
Q

Golgi tendon organ question.

141
Q

Golgi tendon organ question.

142
Q

Skin receptors question.

143
Q

Dorsal column-medial lemniscal system.

144
Q

Neuron question.

145
Q

Resting membrane potential question.

146
Q

Action potential question.

147
Q

Refractory period question.

148
Q

Synapses question.

149
Q

Chemical synapses question.

150
Q

What is a motor unit? Are all motor units the same?

A
  • Motor unit = alpha motor neurone (lower motor neurone) + the extrafusal muscle fibres it innervates
  • No, different motor units innervate different number of muscle fibres, e.g. small motor unit –> increased flexibility (fingers, eyes)
  • Activation of alpha motor neurone depolarises + causes contraction of all fibres in that unit
151
Q

What is a neuromuscular junction? Are they excitatory or inhibitory? What is the motor end plate?

A
  • Neuromuscular junction = space between neuron and muscle fibres (region of muscle fibre that lies directly under terminal portion of axon = MOTOR END PLATE)
  • All excitatory synapses - releases ACh
  • One end plate potential is sufficient to initiate an action potential
152
Q

What do the muscle spindle and Golgi tendon organs detect?

A
  • Muscle spindle detects STRETCH - monitors muscle length and rate of change (contain stretch receptors)
  • Golgi tendon organs are tension receptors that detect TENSION - send sensory information to the brain via spinal cord about amount of force on muscles
153
Q

What are the intrafusal and extrafusal muscle fibres of the muscle spindle innervated by? What types of nerves are the inferior, middle and superior thirds of the spindle associated with?

A
  • Intrafusal fibres innervated by gamma motor neurons (type of lower motor neuron). They set a length that optimises muscle stretch detection
  • Extrafusal fibres innervated by alpha motor neurons
  • Middle third = type 1a afferent sensory nerves (FAST)
  • Superior/inferior thirds = type 2 afferent sensory nerves (SLOW)
154
Q

Where are Golgi tendon organs found? How do they become activated? Which reflex are they involved in?

A
  • Found at ending of afferent fibres - type 1b afferent fibres
  • Muscle stretched - Golgi tendon organ receptor endings distorted –> ACTIVATED
  • Inverse stretch (myotatic) reflex = afferent neurons from Golgi tendon organ can inhibit alpha motor neurons from contracting to protect muscle from overload
155
Q

What are the three types of reflexes? Give examples.

A
  • Stretch, e.g. Knee jerk reflex
  • Withdrawal
  • Inverse stretch, e.g. Clasp knife reflex
156
Q

What happens in the knee jerk reflex?

A
  • Physician taps patellar tendon - stretch receptors activated
  • Burst of action potentials in afferent nerves –> activate excitatory synapse of motor neurons innervating these muscles
  • Stimulation of motor units of thigh muscle, causing them to contract –> knee jerk reflex
157
Q

What happens in a withdrawal reflex?

A
  • Painful stimulation –> ipsilateral activation of flexor + inhibits of extensor
  • Opposite reaction on contralateral –> activation of extensors + inhibits flexors
158
Q

What is the clasp knife reflex?

A
  • Bend patient limb - initial resistance, but resistance drastically drops at certain point
  • Characteristic of upper motor neuron lesion
159
Q

What happens in the descending projections from the cortical motor areas?

A
  • Motor command originates in motor cortex pyramidal cells
  • These are upper motor neurons
  • Pyramidal cell axons project directly or indirectly to spinal cord, where they synapse with lower motor neurons
  • The axons of the upper motor neurons form the pyramidal tract
160
Q

What are the differences between upper motor neurons and lower motor neurons?

A
  • UMN:
  • Descending pathways + neurons in motor cortex
  • UMN lesions causes movement problems
  • Muscle wasting over time due to inactivity
  • Hypertonic muscles - uncontrollable movement, muscle spasms –> decrease in fine motor skills
  • Babinski sign –> dorsiflexed toe
  • Clasp-knife reflex
  • LMN:
  • Motor neurons or cord + brainstem (alpha/gamma)
  • Muscle severely wasted = 7 days, muscle still responds to electrical stimulation, 10 days, reaction to direct current ceases, takes time to notice muscle damage
  • Hypotonic muscles
161
Q

What are the three ascending tracts?

A
  • DCML (dorsal column medial lemniscus)
  • Spinothalamic
  • Spinocerebellar

(Also spinoreticular but not that important)

162
Q

What sensations does the dorsal column medial lemniscus carry? Where are the synapses? Where are the decussations?

A
  • Carry proprioception, vibration + discriminative touch
  • Fasciculus cuneatus = LATERAL + carries info from UPPER BODY to cuneat tubercle in medulla
  • Fasciculus gracilis = MEDIAL + carries info from LOWER BODY to gracile tubercle in medulla
  • Ascends to medulla + then DECUSSATES and SYNAPSES to become medial lemniscus + then ascends to thalamus + SYNAPSES to primary somatosensory cortex
163
Q

What sensations does the spinothalamic tract carry? Where does it synapse?

A
  • LATERAL: pain + temperature
  • MEDIAL: crude touch
  • Ascend on same side for 2-3 vertebra. SYNAPSE and DECUSSATE
  • Up to medulla
  • SYNAPSE
  • Up to primary somatosensory cortex
164
Q

What sensations does the spinocerebellar tract carry? What are the two tracts?

A
  • Carries unconscious proprioception
  • Ventral (anterior) spinocerebellar
  • Dorsal (posterior) spinocerebellar
  • Enter dorsal grey horn, SYNAPSE at nucleus dorsal is (C8-L3)
  • Majority of fibres decussate to form ventral spinocerebellar tract (dorsal fibres remain ipsilateral)
  • Ascend through medulla to cerebellar cortex
165
Q

What are the three types of descending tracts?

A
  • Corticospinal
  • Corticobulbar
  • Vestibulospinal, Reticulospinal, Tectospinal, Rubrospinal
166
Q

Where do the descending tracts originate from?

A
  • Originate from cerebral cortex + brainstem (upper motor neuron)
  • Their role concerns control of movement, muscle tone, spinal reflexes, spinal autonomic functions + transmission of sensory information to higher centres
  • Divided into pyramidal (corticospinal + corticobulbar) and extrapyramidal (vestibulospinal, reticulospinal, tectospinal, rubrospinal)
167
Q

What does the corticospinal tract do? Where does it decussate?

A
  • Transmits control of voluntary muscles (motor)
  • Provides axial and limb motor function via upper motor neurons and lower motor neurons
  • Primary motor cortex –> internal capsule –> medullary pyramids
  • 90% decussate here (lateral)
  • 10% decussate at white commissures (anterior), i.e. stay ipsilateral
  • SYNAPSE with LMN, out of spinal cord via anterior horn
  • Terminate at neuromuscular junction within motor units
168
Q

What does the corticobulbar tract provide? What is its path?

A
  • Voluntary movement of face and neck
  • Motor and premotor cortex –> internal capsule –> brainstem
  • SYNAPSE with cranial nerve nuclei (lower motor neurone)
  • To face and neck muscles
169
Q

What does the extrapyramidal tract provide?

A
  • Vestibulospinal: muscle tone and posture
  • Reticulospinal: spinal reflexes
  • Tectospinal: head turning to view stimuli
  • Rubrospinal: assists motor functions
170
Q

Anatomically, how is the nervous system divided?

A
  • CNS = brain and spinal cord
  • PNS = 12 pairs of cranial nerves (from brain) and 31 pairs of spinal nerves (from spinal cord)
171
Q

Functionally, how is the peripheral nervous system divided?

A
  • Somatic = controls voluntary activity, consist of a single neurone between CNS + skeletal muscle cells with NO SYNAPSE
  • Autonomic = controls involuntary activities, innervate smooth + cardiac muscle, glands, neurones in the GI tract (enteric nervous system). Has two-neurone chain (connected by synapse) between CNS and effector organ - first neurone has its cell in CNS, synapse between neurones is outside CNS in a cell cluster called autonomic ganglion, neurones passing between CNS + ganglion = preganglionic neurone, neurones passing between ganglia + effector cells = postganglionic neurones
172
Q

What makes up the autonomic nervous system?

A
  • Sympathetic = prepares body for emergencies
  • Parasympathetic = creates state of rest

(Also enteric, can work independently for digestion)

  • The table is slightly wrong - parasympathetic causes vasodilation
173
Q

What is the difference between afferent and efferent neurons?

A
  • Afferent (‘arrive’) = convey information from sensory receptors to CNS. Long part of their axon lies OUTSIDE CNS and is part of PNS. Sometimes called first-order neurons
  • Efferent (‘exit’) = carry signals out from CNS to muscles, glands + other tissues
174
Q

Where do sympathetic fibres leave the CNS? What is the sympathetic trunk? Which neurotransmitters are used?

A
  • Sympathetic fibres leave CNS from T1-L2 of spinal cord
  • Most of ganglia lie close to spinal cord + form two chains of ganglia = sympathetic trunks (one each side of cord)
  • Uses ACh at preganglionic synapse where there are nictinic receptors
  • Uses noradrenaline at effector cell synapse where there are adrenergic receptors
175
Q

Where do parasympathetic fibres leave the CNS? Where do the preganglionic fibres run? What are the neurotransmitter used?

A
  • Parasympathetic fibres leave CNS from brainstem + sacral portion of spinal cord
  • Preganglionic fibres run via: CN3 (to pupil), CN7 (to salivary glands), CN9 (swallowing reflex) + CN10 (thorax + abdomen) - remember 1973
  • Uses ACh at preganglionic neurone where there are nicotine receptors
  • Uses ACh at effector cell synapse where there are muscarinic receptors
176
Q

What is the basal ganglia? Where does it lie?

A
  • Basal ganglia = group of nuclei lying deep within the cerebral hemisphere
  • Spead in the forebrain
177
Q

What are the functions of the basal ganglia?

A
  • Modulates signals in descending motor pathways, so:
  • refine movement
  • control posture + muscle tone
  • inhibit undesired movement
178
Q

What are the most prominent nuclei in the basal ganglia?

A
  • Striatum = putamen + caudate nucleus
  • Lentiform nucleus = putamen + globus pallidus
  • Globus pallidus (external + internal)
  • Substantia nigra
  • Subthalamic nucleus
179
Q

Label this diagram.

A
  • Straitum + globus pallidus = rostral (upper)
  • Substantia nigra + subthalamic nucleus = caudal (lower)
180
Q

Label this diagram.

181
Q

Label this diagram.

182
Q

In the internal capsule, where do somatosensory and motor (pyramidal) pathways pass through?

A
  • Somatosensory pathways pass through posterior 2/3 of posterior limb
  • Motor (pyramidal) pathways pass through genus and anterior 1/3 of posterior limb
183
Q

What are the direct and indirect pathways? Are they excitatory or inhibitory? What neurotransmitters are used?

A
  • Direct pathway (i.e. increasing/making movement). Excitatory. Glutamate is the neurotransmitter
  • Indirect pathway (i.e. decreasing/stopping movement). Inhibitory. GABA is the neurotransmitter
  • Balance between direct + indirect pathway provides smooth movement
184
Q

What happens in the direct pathway?

A
  1. Motor cortex excites straitum using glutamate
  2. Substantia nigra initiates direct pathway
  3. Excited striatum sends inhibitory signals to INTERNAL globus pallidus
  4. Inhibited globus pallidus sends less inhibitory signals to thalamus
  5. Not inhibited, thalamus able to stay active and send more excitatory messages to the primary motor cortex using glutamate. This initiates movement
185
Q

What happens in the indirect pathway?

A
  1. Motor cortex excites striatum
  2. Substantia nigra initiates the indirect pathway
  3. Excited striatum sends inhibitory signals to EXTERNAL globus pallidus
  4. External globus pallidus cannot send an inhibitory signal to the subthalamic nucleus
  5. Not inhibited, subthalamic nucleus sends more excitatory signals to internal globus pallidus, results in release of inhibitory messages to thalamus via GABA
  6. Excited internal globus pallidus sends inhibitory signal to the motor cortex = no eye movement
186
Q

What is the substantia nigra’s role in the direct and indirect pathway?

A
  • Substantia nigra acts upon striatum, inducing either direct (via internal global pallidus) or indirect pathway (via external globus pallidus)
187
Q

What does the release of dopamine cause? What is the cause of Parkinson’s disease?

A
  • Release of dopamine reinforces the desired movements and inhibits the unwanted movement
  • Parkinson syndrome - not enough dopamine is released, which results tremor, bradykinesia, rigid muscles etc.
188
Q

Where is the primary motor cortex located? What is its purpose?

A
  • Located on the pre-central gyrus of the frontal lobe
  • The highest level in the brain for the control of movement
  • In each hemisphere the opposite half of the body is represented in a highly precise fashion
209
Q

What is the region of the muscle fibre plasma membrane that lies directly under the terminal portion of the axon called? How about the junction of an axon terminal with this structure?

A
  • Motor end plate
  • Neuromuscular junction
210
Q

What happens at a neuromuscular junction when an action potential arrives?

A
  • Action potential arrives at axon terminal + depolarises membrane, opening voltage-gated Ca2+
  • Ca2+ moves into axon terminal, causes vesicles to bind with plasma membrane and causes release of ACh
  • ACh diffuses to motor end plate where it binds to cholinergic nicotine cells receptors, this causes ion channels to open, more Na+ moves in than K+ out = depolarisation (end plate potential)
  • Action potential propagated over surface of muscle fibre + into T-tubules, ultimately causing release of Ca2+ from sarcoplasmic reticulum = CONTRACTION
211
Q

Are neuromuscular junctions excitatory or inhibitory?

A
  • All neuromuscular junctions are EXCITATORY
212
Q

What does the vertebral column consist of?

A

7 cervical vertebrae, 12 thoracic, 5 lumbar, sacrum (5 fused vertebrae) and coccyx (fusion of four or more rudimentary vertebrae)

213
Q

This descending motor tract originates in the cerebral cortex and synapses in the spinal cord.

A. Spinocerebellar tract

B. Rubrospinal tract

C. Corticospinal

D. Dorsal column medial lemiscus pathway

E. Spinothalamic

214
Q

Which of the following statements is true?

A. The spinothalamic tract decussates within the spinal cord.

B. The dorsal column decussates within the spinal cord.

C. The corticospinal tract decussates within the spinal cord.

D. The posterior (dorsal) spinocerebellar tract decussates twice while the anterior (ventral) spinocerebellar tract does not decussate at all.

A

A. The corticospinal tract decussates in the pyramids of the lower medulla. The spinothalamic tract decussates within the spinal cord. The dorsal column decussates in the medulla oblongata. It is the anterior (ventral) spinocerebellar tract (blue) that decussates twice – once in the spinal cord as part of the anterior white commissure and then again in the superior cerebellar peduncle. The posterior (dorsal) spinocerebellar tract (red) does not decussate.

215
Q

Which of the following statements regarding the peripheral nervous system is true?

A. The peripheral nervous system excludes the cranial nerves

B. The spinal cord is not part of the peripheral nervous system.

C. The peripheral nervous system is protected by the blood brain barrier.

D. The peripheral nervous system is not myelinated

E. The peripheral nervous system ONLY includes a motor component.

216
Q

The vagus nerve is composed of:

A. Parasympathetic motor fibres

B. Parasympathetic motor and sensory fibres

C. Sympathetic motor fibres

D. Sympathetic motor and sensory fibres

E. All of the these

217
Q

Which group of spinal nerves innervates the bicep reflex?

A. S1/S2

B. C5/C6

C. C7/C8

D. C8/T1

E. L3/L4

218
Q

A 48 year old obese diabetic man, who smokes 30 a day presents with bilateral “glove and stocking” loss of pain, temperature and pin prick sensation. Which of the following spinal tracts is affected?

A. Rubrospinal tract

B. Spinothalamic

C. Corticospinal

D. Spinocerebellar tract

E. Dorsal column medial lemiscus pathway

219
Q

Which cell type listed below is not found in the central nervous system?

A. Astrocytes

B. Ependymal cells

C. Oligodendrocytes

D. Schwann cells

E. Microglia

220
Q

A sexually active 75 year old gentlemen presents with a stamping gait. He is diagnosed with tabes dorsalis. On examination he has a loss of joint position sense and cannot feel the tuning fork (vibration) when placed on his medial malleolus. Which of the following spinal tracts is affected?

A. Spinocerebellar tract

B. Dorsal column medial lemiscus pathway

C. Rubrospinal tract

D. Spinothalamic

E. Corticospinal

221
Q

Which group of spinal nerves innervates the ankle reflex?

A. S1/S2

B. C8/T1

C. C7/C8

D. L3/L4

E. C5/C6

222
Q

Which of the following statements regarding the nerve action potential graph is TRUE?

A. The upstroke is mediated by sodium ions rushing into the cell. The downstroke is mediated by potassium ions rushing out of the cell.

B. The upstroke is mediated by potassium ions rushing out of the cell. The downstroke is mediated by sodium ions rushing into the cell.

C. The upstroke is mediated by potassium ions rushing into the cell. The downstroke is mediated by sodium ions rushing out of the cell.

D. The upstroke is mediated by sodium ions rushing out of the cell. The downstroke is mediated by potassium ions rushing into the cell.

E. The upstroke is mediated by sodium ions rushing into the cell. The downstroke is mediated by Calcium ions rushing out of the cell.

223
Q

A 78 year old lady presents to her GP surgery with an intensely itchy vesicular rash in a horizontal line at the level of the nipple. What is the most likely diagnosis?

A. Allergic reaction

B. Dermatitis Herpatiformis

C. Erythema Multiforme

D. Chicken Pox

E. Shingles

224
Q

A 78 year old lady presents to her GP surgery with an intensely itchy vesicular rash in two separate horizontal lines at the level of the nipple and umbilicus respectively. Which dermatomal distribution is this affecting?

A. T6 and T12

B. T4 and T12

C. T10 and L1

D. T4 and T10

E. C8 and C10

225
Q

What are the cranial nerves innervating the meninges?

A

V1, V2, V3, IX, X

226
Q

What travels through the optic canal, the superior orbital fissure and the inferior orbital fissure?

227
Q

Name these muscles of the eye.

228
Q

Name the innervation and movement of each of these muscles.

229
Q

What is the origin of all of the recti muscles?

A

Common tendinous ring (annulus of Zinn)

230
Q

What are the visual pathway pathologies at B, C, and DGH?

231
Q

Complete this diagram.

232
Q

Where does the cerebellum lie inferiorly to? What is its blood supply? How is different to the cerebrum?

A
  • Lies inferiorly to occipital and temporal lobes, under tectorial cerebelli
  • Blood supply = superior cerebellar artery, anterior inferior cerebellar artery, posterior inferior cerebellar artery
  • In cerebrum we have gyri and sulci, in the cerebellum we have folia and fissures
233
Q

What are the lobules of the vermis?

A
  • Mnemonic = Like Cats Catching Dogs For The Party Up North
  • Lingula
  • Central lobule
  • Culmen
  • Declive
  • Folium
  • Tuber
  • Pyramid
  • Uvula
  • Nodule
234
Q

Complete this diagram.

235
Q

What are the functional lobes of the cerebellum?

236
Q

What are the three cerebellar pathways?

237
Q

What are the signs of cerebellar damage?

A
  • Remember DANISH
  • Dysdiadokinesia and dysmetria
  • Ataxia
  • Nystagmus
  • Intention tremor
  • Slurred speech
  • Hypotonia

Phase 1 (17 decks)

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