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Medicine - Year 2 > Block 12 - Musculoskeletal and nervous system (nervous 1) > Flashcards

Block 12 - Musculoskeletal and nervous system (nervous 1) Flashcards

1
Q

Where is information from the eye processed?

A

Lateral geniculate nucleus in the thalamus

Thalamus neurones –> Primary visual cortex and striate cortex (myelinated)

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2
Q

How does light get to the fovea?

A

Light –> Cornea –> Pupil –> Lens –> Fovea

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3
Q

Explain the visual fields of the eye, how they are seen and how they are processed by the brain

A

The left visual field of both eyes is seen by the right side of each eye and processed by the right side of the brain

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4
Q

What are the 3 layers of the eye?

What does each layer contain?

A
  1. Fibrous layer: Outer layer made from clear cornea and white sclera
  2. Vascular layer: Iris (colour), Ciliary bodies (muscles to change lens shape) Choroid (vessels at the back of the eye)
  3. Neural layer: Inner later containing retina (neurones send info to the optic nerve)
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5
Q

What are the 2 classes of movement of the eye?

What do they allow to happen?

A

Conjugate: Eyes move in the same direction
Disconjugate: Eyes move in opposite directions

Allows the image to stay on the fovea (increases resolution)

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6
Q

Define the 4 types of conjugate movements?

A

Vestibulooccular: Eye fixes whilst head rapidly moves (vestibular)
Optokinetic: Eye fixes whilst head slowly moves (visual)
Saccade: Eye directed towards various targets
Smooth pursuit: Allows you to follow a moving target

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7
Q

Define the 1 type of disconjugate movement

A

Vergence: Adjusts the eyes by convergence/divergence for objects far/close

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8
Q

What are the 2 movements of gaze stabilisation?

A

Vestibuloochlear

Optokinetic

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9
Q

What are the 3 movements of gaze shifting?

A

Saccade
Smooth pursuit
Vergence

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10
Q

Define adduction and abduction of the eye

A

Adduction: Eye moves towards the nose
Abduction: Eye moves away from the nose

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11
Q

Define intorsion and extorsion of the eye

A

Intorsion: Top of the eye moves towards the nose and the bottom of the eye moves away from the nose
Extorsion: Top of the eye moves away from the nose and the bottom of the eye moves towards the nose

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12
Q

What are the 8 areas of the brain which centrally control eye movements?
What are their roles

A 
Supplementary eye field (decision and planning)
Frontal eye field (execution)
Prefrontal cortex (decision and planning)
Caudate nucleus (modify motor commands)
Posterior parietal cortex (visuospacial integration)
Superior colliculus (sensory integration)
Reticular formation (coordination)
Brainstem nuclei (final common pathway)
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13
Q

Give 2 examples of muscular structures which open and close the eye

A

Iris and ciliary body

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14
Q

How is the ciliary body attached to the lens?

A

Ciliary body atatched to zonule fibres which are attached to the lens

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15
Q

How do sympathetic nerves control the pupil?

A

Superior cervical ganglion > Carotid plexus > Opthalamic nerve

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16
Q

How do parasympathetic nerves control the pupil?

A

Edinger-Westphal + occulomotor nucleus > Occulomotor nerve > Ciliary ganglion > Sphincter muscle

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17
Q

What is the pathology in Anisocoria?

A

One pupil is unable to constrict

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18
Q

What is the purpose of the accommodation reflex?

A

To increase resolution

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19
Q

What happens to the lens, ciliary muscles and suspensory ligaments when looking at a distant object and a close object?
What does this allow to happen?

A 
Distant object (decrease focus):
lens flat and thin, muscles relaxed, ligaments tense
Close object (increase focus)
lens round and thick, muscles tense, ligaments relaxed
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20
Q

What is another word for ‘clouding’

A

Opacification

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21
Q

6 risk factors for cataracts

A

Age, trauma, diabetes, UV

Smoking, genetic

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22
Q

Explain how aqueous humour is produced

A

Aqueous humour produced in the ciliary processes behind the ciliary body in the anterior chamber (between lens, iris and cornea)

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23
Q

Where is the anterior chamber angle?

A

Between the iris and cornea

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24
Q

Where does aqueous humour circulate?

A

lens > iris > pupil > anterior chamber > trabecular meshwork > schlemm’s canal

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25
Q

What is the cause of the 2 types of glaucoma?

A

Primary open-angle: Trabecular meshwork clogged causing gradual vision loss
Acute angle-closure: Iris bows so anterior chamber angle closes and blocks drainage

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26
Q

4 risk factors for glaucoma

A

Hypertension, LT corticosteroid use, Increased intraoccular pressure, Severe myobia (nearsightedness secondary to eye injury/surgery)

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27
Q

How do you measure the intraoccular pressure?

How do you look at the retina?

A

Tonometry

Optical coherance tomography

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28
Q

What are the inner and outer vessels in the eye?

A 
Inner = Retinal vasculature
Outer = Chonocapillaries
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29
Q

What are the 9 cells/layers of the retina?

What does each layer do

A

Optical nerve fibres (ganglion cell axons)
Ganglion cells (send axons to the optic nerve)
Amacrine & Horizontal cells (integrate info across eye)
Bipolar cells (info from photoreceptors > ganglion cells)
Photoreceptors (rods and cones)
Pigment epithelium (outer layer supplies photorecep)
Bruch’s membrane
Choroid

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30
Q

What causes mild colourblindness?

A

If 2 cones see similar wavelenths of light

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31
Q

What are dichromats

What are the 3 types?

A

They only have 2 cone types
Protanopes = no red
Deutrenaopes = no green
Tritanopes = no blue

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32
Q

What are trichromats?

A

They have 3 cone types but the sensitivity of one is shifted towards the other

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33
Q

What are the 2 parts of the lateral geniculate nucleus?

A

Magnocellular: Bottom layer, input from A ganglion cells to see in greyscale and see WHERE

Parvocellular: Top layers, input from B ganglion cells to see in colour and see WHAT

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34
Q

Where is the central and peripheral visual field projected onto in the brain?

A 
Central = back of the brain
Peripheral = anterior brain
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35
Q

What are the 2 specialised visual fields of the occipital lobe?
What happens if there is a lesion?

A

V4: Ventral surface to see colour (lesion = achromatopsia)
V5: Lateral surface to see motion (lesion = akinetopsia)

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36
Q

What do the magno and parvo regions send information to?

What happens if there is a lesion in one of these areas?

A

Posterior parietal cortex: Lesion > optic ataxia (balints)
Do not know WHERE things are

Inferotemporal cortex: Lesion > visual agnosia
Do not know WHAT the object are

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37
Q

What 3 things make up the cerebral cortex?

A

Lobes, Pons and Brainstem

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38
Q

Define dyspraxia/apraxia

A

Inability to plan and sequence events

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39
Q

What happens to the eyes if there is a lesion in the frontal lobe?

A

Eyes deviated to the side of the distraction, away from the side of irritation (e.g. stroke in left, eyes to left)

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40
Q

Where do the primary motor neurones originate from?

A

Area 4 (Brodmans)

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41
Q

How are the corticospinal tract neurones arranged in the brain and spinal cord?

A

Brain = Cervical lateral and Sacral medial

Spinal cord = Cervical medial and Sacral lateral

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42
Q

Where are the cranial nerve motor nuclei?

A

Midbrain: 3,4
Pons: 5, 6, 7
Medulla: 9, 10, 11, 12

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43
Q

Where will the weakness be if there is a lesion to the cranial nerve nuclei?

A

Ipsilateral LMN weakness

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44
Q

What side will homonymous hemianopia affect?

A

Contralateral side to the lesion

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45
Q

What is the role of the frontal lobe? (9)

A 
Intellectual, Motor praxis (planning and sequencing), Inhibition, Motor function, Personality, Social behaviour
Language expression (Broca's), Bladder continence, Saccidic (voluntary) eye movement
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46
Q

What is the role of the occipital lobe? (2)

A

Sees visual information (doesn’t interpret)

Hand-eye coordination

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47
Q

What is the role of the temporal lobe? (4)

A

Primary senses and emotion (linked to autonomic = cry)
Memory
Facial recognition

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48
Q

What is the role of the parietal lobe? (4)

What is the role of the dominant and non-dominant lobe?

A

Interprets sensory information
Language reception (Wernicke’s)
Object recognition
Learned skills

Dominant: numbers
Non-dominant: Body image & environment awareness

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49
Q

Define sensory dyspraxia

A

Reduced visuospacial skills, ‘tone deaf’, can see a word but cannot interpret it (dyslexia)

Clumsy, vomiting, difficulty walking

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50
Q

Signs of a:

  1. dominant parietal lobe lesion (4)
  2. non-dominant parietal lobe lesion (2)
  3. signs found in both (4)
A
  1. Dyslexia, Acalculia (maths), Finger agnosia (cannot distinguish fingers), Poor left-right discrimination
  2. Sensory extinction, Visuospacial apraxia (don’t recognise half of the body)
  3. Agraphaesthesia (can’t write), Alterogenesis (can’t feel), Reduced 2 point discrimination, Stimuloagnosia (can see an object but it’s not in the right setting)
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51
Q

What do spinothalamic tracts sense?

How do they travel to the brain?

A

Pain and temperature
Cross the midline at the level they enter and ascend contralaterally to the thalamus > internal capsule > sensory parietal cortex

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52
Q

What do posterior column tracts sense?

How do they travel to the brain?

A

Joint position, deep pressure and vibration

Ascend ipsilaterally and decussate in the medulla > thalamus > sensory parietal cortex

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53
Q

What happens to the spinothalamic and posterior columns there is a lesion in the:

  1. upper brain sensory tracts?
  2. left spinal cord?
A
  1. Contralateral sensory deficit
  2. Contralateral spinothalamic loss below the level of the lesion
  3. Ipsilateral posterior column loss below the level of the lesion
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54
Q

Which cranial nerve nuclei originate in the medial brainstem and lateral brainstem?

A 
Medial = motor
Lateral = sensory
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55
Q

What do lesions in the red nucleus cause?

What does the red nucleus normally do with (2)?

A 
Contralateral tremor
(involved in motor coordination along with the basal ganglia and thalamus)
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56
Q

What system is involved in wakefulness?

A

Reticular activating system

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57
Q

Explain what happens in Weber (midbrain) Syndrome (2)

A 
Ipsilateral occulomotor (III) palsy
Contralateral motor dysfunction
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58
Q

Explain what happens in Wallenburg (lateral medullary) Syndrome (6)

A

Impaired gag reflex, Altered taste, Vertigo, Checkerboard sensory loss (ipsilateral face, contralateral body
Ipsilateral ataxia, Horners

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59
Q

What are the 3 parts of the cerebellum?

A

Vermis (vestibulocerebellum): Balance and equilibrium
Paravermis (spinocerebellum): Postural tone
Cerebellar hemispheres (ponto/neocerebellum): Fine coordiantion

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60
Q

Do cerebellar lesions present insilaterally or contralaterally?

A

Ipsilaterally

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61
Q

What does VANISH’D stand for?

A

Vertigo, Ataxia, Nystagmus, Intention tremor, Slurred Staccato Scanning Speeh, Hypotonia, Dysmetria (can’t control tone), Dysdiadochokinesis

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62
Q

What is the role of the thalamus?

A

Processes sensory and motor information

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63
Q

Give 3 examples of thalamic lesions

A

Ventroposterior lesion: Severe pain syndrome
Ventral posterolateral lesion: Surgery and deep pain stimulation for parkinsons
Anterior and contromedian lesion: Mood and behaviour disorders

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64
Q

What word describes pupil dilation and constriction?

A 
Miosis = constriction
Mydriasis = dilation
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65
Q

5 symptoms of a thalamic stroke

What area is impacted to case each?

A 
Posterior = sensation
Lateral geniculate = vision
Medial geniculate = auditory
Anterior lateral = movement control
Anterior medial = limbic
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66
Q

Give an example of a tumour of the optic nerve

A

Glioblastoma

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67
Q

Positive and negative symptoms of vision

A 
Negative = no vision
Positive = irritation of visual structures
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68
Q

3 symptoms of a CNIII lesion

A 
Eye down and out
Pupil dilated (parasympathetic)
Partial ptosis from levator palpebrae superioris lesion
69
Q

6 causes of Horner’s

A 
Idiopathic abnormal sympathetic supply
Cluster headaches
Internal carotid pathology
Lateral medullary patholoy
Pancoast syndrome
C8/T1 pathology
70
Q

Which fibres run on the outside of the nerve?

A

Parasympathetic

71
Q

Is pupil constriction and dilation controlled by sympathetic or parasympathetic nerve innervation?

A 
Constriction = parasympathetic
Dilation = sympathetic
72
Q

1 symptoms of a CNIV palsy

A

Can’t look down and in

73
Q

2 causes of a CNVI palsy

3 symptoms

A

Pontine lesion or ischaemic mononeuritis (loss of blood to eye) in the elderly
Double vision
Neck ache and headache (tilt head to see normally)

74
Q

Define diplopia

A

Double vision

75
Q

Explain the difference between a LMN lesion and an UMN lesion in the facial nerve

A 
LMN = weakness on the same side as the insult
UMN = weakness on the opposite side of the insult (forehead sparing)
76
Q

5 signs of a LMN facial nerve palsy

A 
Ipsilateral
Hyperacussis
Lacrimation reduced
Incomplete closure of the eye
Abnormal taste and sensation to the anterior tongue
77
Q

What are the 2 muscles which are paralysed in an accessory nerve palsy?

A

Right trapezius

Sternocleidomastoid

78
Q

5 symptoms of a LMN lesion of the hypoglossal nerve

A 
Tongue wasting
Fasiculations
Weakness
Dysarthria
Tongue deviated to the side of the lesion
79
Q

Define dysarthria

A

Reduced speech

80
Q

Explain the stages of grading muscle power

A

0: no movement
1: flicker of movement
2: movement with gravity removed
3: movement against gravity
4: movement against resistance
5: normal movement

81
Q 
What happens to \_\_\_\_ in a UMNL / LMNL?
muscle bulk 
posturing
fasiculations
tone
power
reflexes (and plantar response)
A

Muscle bulk: reduced in both
Posturing: spastic in upper
Fasiculations: in lower (not upper)
Tone: increased in upper and decreased in lower
Power: reduced in both
Reflexes: increased in upper an decreased in both
Plantar: in upper

82
Q

Explain what happens in decerebrate posturing

A

Upper brain stem damage (BAD)
Arms adducted and extended
Wrists pronated with finger flexes
Legs stiffly extended and feet plantar flexed

83
Q

Explain what happens in decorticate posturing

A 
Corticospinal tract damage (BETTER)
Arms adducted and flexed
Wrists and fingers flexed on chest
Legs stiffly exttended and internally rotated
Feet plantar flexed
84
Q

3 things which degrade in motor neurone disease

What signs do they cause?

A

Degradation of corticol motor neurones (UMN signs)
Degradation of brainstem motor nuclei (LMN cranial nerve signs)
Degradation of anterior horn cells (LMN limb signs)

85
Q

How are the cervical and sacral tracts tonographically organised in spinothalamic and posterior column tracts?

A

Spinothalamic = sacral lateral and cervical medial

Posterior columns = sacral medial and cervical lateral

86
Q

Where does the spinal cord end in children and adults?

A 
Adults = L1/L2
Children = L3/L4
87
Q

What are the 3 signs in Brown-Sequard?

A

Ipsilateral motor and posterior column signs (UMN weakness and reduced position and vibration)

Contralateral spinothelamic signs (reduced pain and temperature)

88
Q

Cervical disc prolapse (4)

A

Ipsilateral LMN signs at lesion
Ipsilateral UMN signs below lesion
Altered sensation of C5/6 dermatome
Weakness and wasting of biceps muscle and reduced biceps tendon reflex

89
Q

Lumbar disc prolapse (4)

A

Positive straight leg raise sign
Ipsilateral weakness of L4/L5 muscles and dermatome
Ipsilateral loss of knee reflex

90
Q

What is a syrinx?
What can happen to it?
What 2 things can this cause?
What 2 things are spared - why?

A

A cord within the spinal cord filled with CSF
Usually closes as we develop but can remain and tear in trauma
Causes hung sensory loss in the band affected and UMN signs below if lesion more medial and affects motor tracts
(spinothalamic and posterior not affected as lesion is medial)

91
Q

3 things a lesion in the anterior spinal artery causes

A

Bilateral motor loss below
Bilateral spinothalamic loss below
Bilateral posterior retained

92
Q

What are the 4 symptoms of parkinsons?

A

T: tremor at rest
R: rigidity
A: akinesia (no/slow movement)
P: postural instability

93
Q

What causes a high steppage or antalgic gait?

A

Sensory loss in the feet

94
Q

2 features of a cerebellar gait

A

Broad base and unsteady

95
Q

What causes a waddling gait?

A

Proximal leg muscle weakness

96
Q

What causes an atasia-abasia gait?

A

Psychological

97
Q

Explain how to carry out Romberg’s test

What do the results mean?

A

Patient stands with feet together, looks ahead then closes eyes
Wobble = reduced sensory awareness in feet/ vestibular dysfunction

98
Q

Define posture

A

Position of body parts with respect to each other, the environment and gravity

99
Q

Define postural equilibrium

What is the difference between static and dynamic?

A

When all the forces acting upon the body are balanced
Static = balance when still
Dynamic = balance when moving

100
Q

What do you need to maintain posture?

A

Extensor tone

101
Q

What is the role of ventromedial tracts?

Where do they run from and to?

A

Run from the brainstem to the spinal cord

Tells the muscles information about posture so they can control posture through axial or proximal muscle movements

102
Q

What do ventromedial tracts synapse with in the spinal cord?

A

Alpha LMN in the ventral horn

103
Q

Describe the somatotropic arrangement of ventromedial tracts

A 
Medial = postural control through axial/proximal muscles
Lateral = voluntary control through distal muscles
104
Q

What are the names of the 4 ventromedial tracts?

A

Vestibulospinal
Tectospinal
Pontine reticulospinal
Medullary reticulospinal

105
Q

Which tracts keep the head balanced on the shoulders as the body moves to control head and neck posture?

A

Vestibulospinal

Tectospinal

106
Q

What is the pathway of the vestibulospinal tract?

What is its role?

A

Vestibular labyrinth > medulla vestibular nuclei > spinal cord
Maintains upright posture through extensor motor neurones in the legs

107
Q

What is the pathway of the tectospinal tract?

What is its role?

A

Retina > superior colliculus in midbrain > spinal cord

Directs the head and eyes to move to a particular location

108
Q

What inputs are the pontine and medullary reticulospinal tracts controlled by?

A

Controlled by cerebellum and cortex inputs

109
Q

Where does the pontine reticulospinal tract originate?

What is its role?

A

Pontine reticular formation > spinal cord
Increases antigravity reflexes of the spinal cord
Maintains standing posture against gravity by facilitating lower limb extensors

110
Q

Where does the medullary reticulospinal tract originate?

What is its role?

A

Medullary reticular formation
Liberates antigravity muscles
Allows posture adjustment
(opposite to pontine)

111
Q

What does the superior colliculus do?

A

Integrates sensory information to localise objects and orientate the body

112
Q

What is the vestibular system?

What are the 2 parts?

A

Sensory system in the inner ear to detect gravity and control balance and motion
Otolith organs
Semi-circular canals

113
Q

Where and how does the vestibular system send information to?

A

Hair cells (in otolith organs and semi-circular canals) convert motions to neural signals > vestibular branch of CN VIII

114
Q

What are the 2 otolith organs

A

Utricle and Saccule

115
Q

Define macula

A

Sensory epithelium in the otolith organs containing matrix and hair cells

116
Q

How is the macula orientated in the utricle and saccule?

What movement does it sense?

A 
Utricle = horizontal (senses horizontal movement)
Saccule = vertical (senses vertical movement)
117
Q

Explain how Otolith organs send neural signals

A

Hair cells penetrate into a gelatinous cap
The cap is covered in a layer of crystals

When the head tilts, gravity pulls the crystals and cap down causing the hair cells to bend

118
Q

What causes a hair cell to depolarise/hyperpolarise?

A

Depolarise: hair cell bends towards longer kinocilium
Hyperpolarise: hair cell bends away from kinocilium

119
Q

What is the centre of the utricle/saccule called?

A

Striola

120
Q

How are the hair cells orientated towards the striola in the utricle/saccule?
How are they depolarised

A 
Utricle = kinocilia towards the striola
Saccule = kinocilia away from striola

Depolarised = hair bends towards the striola

121
Q

What are the semi-circular canals sensitive to?

What are they called?

A

Head rotation and acceleration

Anterior, Posterior, Horizontal

122
Q

Explain how the semi-circular canals work

A

Head rotation > cupula (gelatinous cap with cilia) bend in the opposite direction due to inertia of the endolymph
Hair cells bend then depolarise

123
Q

Explain the purpose of the vestibulo-ocular reflex

A

When the head turns, the eyes move in the opposite direction to compensate for head movement

124
Q

Explain how the vestibulo-ocular reflex works

(when the head turns to the left)

A

Semi circular canal > vestibular nuclei > occulomotor and abducens nuclei
Abducens: flexes R lateral rectus
Occulomotor: flexes L medial rectus
Eyes to the right

125
Q

What is the vestibular-ocular reflex test called?

A

Caloric testing

126
Q

What are the 2 postural reflexes?

A

Protective reflexes

Limb placing reflexes

127
Q

What is the role of protective reflexes
Example
How do they work?

A

Maintains CoM over BoS
e.g. extends the hands and dorsiflexes head when you fall

Semicircular canals detect > medial vestibular nucleus > head position through neck muscles + lateral vestibular nucleus > trunk/limb muscles

128
Q

Explain the 2 limb placing reflexes

A

Positive supporting action: Reflex to stiffen a limb when you place it on the ground
1a afferents and alpha motor neurones increase limb tone

Hopping reaction: If the feet are destabilised the body hops to a stable position

129
Q

Give an example of adaptation of postural control

A

Vestibular system adapts e.g. sailors adapt to the motion of the sea

130
Q

Explain the pathophysiology of Meniere’s syndrome

3 symptoms

A

Sudden decrease in endolymph disrupts the labyrinth in the inner ear
Vertigo, deafness, tinnitus

131
Q

What is the treatment for Meniere’s syndrome?

A

No cure but can treat vertigo and nausea with antihistamines and prochorperazine (severe)

132
Q

Define the feedforward/anticipatory response?

What brain area is important?

A

Postural adjustments made before voluntary movements

Reticular formation

133
Q

Define the feedback/compensatory response?

What brain area is important?

A

Responses to sensory stimuli following the postural disturbance
Vestibular nuclei

134
Q

Explain the pathophysiology of benign paroxysmal positional vertigo
3 symptoms

A

Crystals dislodge from otolith organs disrupting endolymph in semi circular canals
Nausea, vomiting, dizzy when moving head or rolling over

135
Q

What is the treatment for benign paroxysmal positional vertigo?

A

Epley/Semont manovure to position the crystals in the cap

136
Q

Define sound

A

An oscillation of pressure through a compressible medium

137
Q

What is pitch?

A

Frequency

138
Q

What is normal human frequency?

A

20 - 20,000 Hz

139
Q

What is the amplitude of the sound wave called?

A

Intensity (volume)

140
Q

Which bone makes up the ear?

A

Petrous part of the temporal bone

141
Q

What is the role of the outer ear?

A

To convert sound waves (acoustic energy) to kinetic energy

142
Q

What is the ear canal called?

A

External auditory meatus

143
Q

What provides protection in the external auditory meatus?

A

Hair
Sebaceous glands
Cervminous glands

144
Q

What shape is the eardrum?

What is it made from?

A

Concave

Collagen

145
Q

What are the ossicles attached to?

A

Malleus attached to eardrum > Incus > Stapes attached to the oval window

146
Q

What is the role of the middle ear?

A

Convert kinetic energy to hydraulic energy

147
Q

Which bone does the tensor tympanii muscle attach to?

A

Malleus

148
Q

What is the role of the acoustic/attenutation reflex?

A

To reduce the sound of your own voice during speaking (stapedius) or chewing (tensor tympanii)

149
Q

What are the 2 branches of the facial nerve which run to the middle ear?
What are their roles?

A

Stapedial nerve > stapedius muscle

Chord tympanii > over tympanic membrane to anterior 2/3 tongue

150
Q

What does the mandibular branch of the trigeminal nerve innervate?

A

Tenso tympanii muscle

151
Q

What frequency does bone conduction hear better?

A

Lower

152
Q

What is the role of the inner ear?

A

Convert hydraulic energy > electrochemical signals

153
Q

What is the bony labyrinth of the inner ear made from?

A

Temporal bone

154
Q

What is the membranous labyrinth of the inner ear made from?

A

Bony labyrinth filled with endolymph (contains K) separated by perilymph (contains Na)

Scala media = endolymph (middle)
Scala vestibuli and tympani = perilymph (either side)

155
Q

What are the 2 membranes in the inner ear?

What do they separate?

A

Reissner’s membrane: separates the vestibuli and media

Basilar membrane: Separates the media and the tympani

156
Q

What is the organ of corti?

A

Sensory epithelia on the basilar membrane containing hair cells which convert vibrations to nerves
Outer hair cells > Inner hair cells > Nerve

157
Q

Draw the cochlea

A

Find an image dumbass i cannot afford pro

158
Q

Define ultrasound and infrasound

A

Ultrasound: Frequency above the human hearing range
Infrasound: Frequency below the human hearing range

159
Q

Explain how a sound wave passes through the cochlea

A

Stapes > Perilymph > Down cochlea along scala vestibuli (upper part) > Basilar membrane > Back up cochlea along scala tympani (lower part) > Round window

160
Q

Explain the pathway of the vestibulocochlear nerve

What is the mnemonic?

A

Ear > Cochlear nuclei in brainstem >(DECUSSATE)> Superior olivary complex > Lateral lemniscus > Inferior colliculis > Medial geniculate nucleus > Auditory cortex in the temporal lobe

SLIM

161
Q

Explain how sound is localised in the vertical plane

A

Pinna, Head, Shoulders, Torso

Use the way sound bounces off them to work out where the sound is

162
Q

Explain how sound is localised in the horizontal plane

A

Decussation allows soumd inputs to be compared in the superior olivary nuclei

Medial: detects differences in TIME (low freq sound)
Lateral: detects differences in INTENSITY (high freq)

163
Q

Define low and high frequency

A

Low less than 800
High more than 1000
(middle by both mechanisms)

164
Q

Give 7 examples of sensioneural hearing loss

A

Age, Childhood/Inflammatory disease Congenital, Meniere’s, Noise, Ototoxic drugs, Physical trauma

165
Q

Is disruption of the tympanic membrane a conductive or sensorineural hearing loss?

A

Conductive

166
Q

Which test is Rinne’s test and which is Weber’s

A

Mastoid process = Rinne

Forehead = Weber

167
Q

What does it mean if the normal ear sounds louder in Weber’s test?
Why?

A

Sensioneural

Sound travelling directly to inner ear via skull bones is masked by ambient noise entering the middle ear

168
Q

What does it mean if the defective ear sounds louder in Weber’s test?
Why?

A

Conductive

Reduced sound travelling through the middle ear so sound travelling from tuning fork to inner ear via skull is louder

169
Q

Why does Rinne’s test not distinguish between normal and sensioneural?

A

Air and bone conduction are both bad in sensioneural

Medicine - Year 2 (19 decks)

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