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Year 2 Medicine Leeds > Neuro Anatomy > Flashcards

Neuro Anatomy Flashcards

1
Q

What are the three types of neurone?

A

Bipolar
Pseudo-unipolar
Multipolar

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2
Q

What are the anatomical subdivisions of the CNS?

A

Cerebrum - forebrain
Brainstem - midbrain, pons, medulla oblongata
Cerebellum
Spinal Cord

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3
Q

What do the cerebral hemispheres develop from?

A

Prosencephalon to telencephalon to cerebral hemispheres

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4
Q

What does the diencephalon develop from?

A

Prosencephalon

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5
Q

What does the mid brain develop from?

A

Mesencephalon

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6
Q

What do the pons and cerebellum develop from?

A

Rhombencephalon to mesencephalon to pons and cerebellum

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7
Q

What does the medulla oblongata develop from?

A

Rhombencephalon to myelencephalon to medulla oblongata

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8
Q

What is the diencephalon?

A

Innerbrain - thalamus, epithalamus(including pineal gland), sub thalamus and hypothalamus

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9
Q

What is white matter?

A

Bundles of axons - transmits information from one area to another

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10
Q

What is the corpus callosum and where is it located?

A

Between the cerebral hemispheres, white matter

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11
Q

What is grey matter?

A

Nerve cell bodies

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12
Q

What is lissencephaly?

A

Smooth brain - lacks gyri and sulci

- gene linked brain malformation - learning difficulties

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13
Q

What are the four lobes of the cerebral hemispheres and describe their anatomical location?

A

Frontal - separated from parietal by central sulcus, contains the pre central gyrus
Parietal - contains the post central gyrus separated from the occipital lobe by the parietooccipital sulcus
Occipital - posterior brain
Temporal - separated from the frontal and parietal lobes by the lateral fissure, lateral brain

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14
Q

What are the functions of the thalamus and hypothalamus?

A

Thalamus - relay station between brainstem, spinal cord and cerebral cortex
Hypothalamus - controls the autonomic nervous system

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15
Q

How many subdivisions of the CNS are there?

A

7

cerebral hemispheres, diencephalon, mid brain, medulla, pons, cerebellum and spinal cord

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16
Q

How many bones form the skull, how are they connected and what is the one exception?

A

22 Bones

Fibrous sutures connect the bones together except from the temporomandibular joint which is a synovial joint

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17
Q

What are the three sinuses?

A

Frontal, ethmoid and maxillary

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18
Q

What is the Pterion?

What is the clinical significance?

A

Junction of parietal, frontal, sphenoid and temporal bones of the skull
- Fracture of this area can cause significant bleeding - extradural haematoma/haemorrhage

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19
Q

Describe the three meningeal layers surrounding the CNS

A

Dura mater - most superficial, very fibrous and tough - periostea and meningeal layers
Arachnoid Mater - Thin layer
Pia mater - very thin follows the gyri and sulci

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20
Q

What are the three dural folds?

A

Falx cerebri - sickle shaped superior
Tentorium cerebelli - transverse plane
Falx cerebelli - separates two cerebellar hemispheres

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21
Q

Where is CSF produced?

A

Ventricles by specialised areas of ventricular lining choroid plexus

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22
Q

Describe the ventricular system of the brain

A

4 ventricles - 2 lateral ventricles, 3rd ventricle between thalami and 4th ventricle between pons and cerebellum

  • Contains the choroid plexus
  • Median aperture (foramen of magendie)
  • Lateral apertures (foramina of luschka)
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23
Q

Why is the lumbar cistern a favoured site for CNS sampling?

A

Spinal cord ends before the site therefore less likely to damage spinal cord during the procedure

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24
Q

Describe the vertebral artery

A

Branch of subclavian, ascend in the neck through the transverse foramen of the cervical vertebrae and enter skull via foramen magnum,
Fuse at the base of the brainstem to form the basilar artery

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25
Q

What arteries make up the circle of willis and its branches?

A 
Anterior communicating 
Anterior cerebral 
Middle cerebral 
Internal carotid 
Posterior communicating 
Posterior cerebral 
Basilar
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26
Q

What does the anterior cerebral artery supply?

A
  • Superior and medial areas of frontal and parietal lobes

- corpus callosum

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27
Q

What does the middle cerebral artery supply?

A
  • Lateral areas of frontal, temporal and parietal lobes
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28
Q

What does the posterior cerebral artery supply?

A
  • Occipital lobe

- Inferior and medial surface of temporal lobe

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29
Q

What do the striate arteries supply?

A
  • Deep nuclei
  • Deep grey matter
  • Internal capsule
  • Major descending motor pathway
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30
Q

Where do superficial and deep veins drain in the brain?

A

Superficial - dural sinuses

Deep - great cerebral vein

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31
Q

Describe the pathway of venous drainage of deep veins

A 
Internal cerebral veins 
Great vein of Galen 
Straight sinus 
Confluence sinuses 
Transverse sinus 
Sigmoid sinus 
Internal Jugular vein
I gave some cheese to Sarahs interns
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32
Q

Describe what arteries cause epidural, subdural and subarachnoid haemorrhages

A

Epidural - torn meningeal artery
Subdural - torn bridging veins
Subarachnoid - torn cerebral arteries

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33
Q

Describe the tectum, tegmentum and basal area of the brainstem

A

Tectum - posterior to ventricular system
Tegmentum - anterior to ventricular system
Basal area - most ventral part

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34
Q

Describe the pyramids and olives as part of the medulla

A

Pyramids - medial raised areas containing descending bodies of motor fibres
Olives - lateral to pyramids

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35
Q

Describe the connections of the cerebellar peduncles

A

Superior - connects midbrain to cerebellum and forms roof of 4th ventricle
Middle - connects pons to cerebellum
Inferior - connects medulla to cerebellum

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36
Q

Damage to what area of the brain induces a coma?

A

Ascending reticular activating system

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37
Q

What is the function of the cerebellum?

A

Coordination, movement, maintenance or balance and posture

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38
Q

What is the foramina and function of cranial nerve I?

A

Olfactory Nerves

  • Cribriform plate
  • Special sensory - smell (olfaction)
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39
Q

What is the foramina and function of cranial nerve II?

A

Optic Nerves

  • Optic canals
  • Special sensory - vision
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40
Q

What is the foramina and function of cranial nerve III?

A

Oculomotor Nerve

  • Superior orbital fissure
  • Somatic motor to 4 extra ocular muscles and levator palpebral superioris
  • Visceral motor to cillary muscle and sphincter pupillae
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41
Q

What is the foramina and function of cranial nerve IV?

A

Trochlear Nerve

  • Superior orbital fissure
  • Somatic motor to superior oblique
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42
Q

What is the foramina and function of cranial nerve VI?

A

Abducens Nerve

  • Superior orbital fissure
  • Somatic lateral rectus
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43
Q

What is the foramina and function of cranial nerve V?

A 
Trigeminal 
V1 - Ophthalmic division 
- Superior orbital fissure 
- Somatic sensation from upper face 
V2 - Maxillary Division 
- Foramen Rotundum 
- Somatic sensation from middle face 
V3 - Mandibular Division
- Foramen ovale 
- Somatic sensation from lower face mandible and anterior 2/3 tongue 
- Branchial motor to muscles of mastication, anterior belly of digastric, tensor tympani
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44
Q

What is the foramina and function of cranial nerve VII and the five main branches?

A

Facial Nerve

  • Internal acoustic meatus (Enter), stylomastoid foramen (Exit)
  • Branchial motor to muscles of facial expression, stapedius muscle, posterior belly of digastric
  • Special sensory as taste to anterior 2/3 of tongue
  • Somatic sensory to skin of ear
  • Visceral Motor to all glands except parotid

Temporal, zygomatic, buccal, mandibular and cervical

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45
Q

What is the foramina and function of cranial nerve VIII?

A

Vestibulocochlear Nerve

  • Internal acoustic meatus
  • Special sensory, hearing and balance
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46
Q

What is the foramina and function of cranial nerve IX

A

Glossopharyngeal

  • Jugular Foramen
  • Branchial motor for swallowing
  • Visceral motor to parotid
  • Special sensory for taste to posterior 1/3 tongue
  • Somatic sensory to middle ear, pharynx, posterior 1/3 tongue
  • Visceral sensation from carotid body and carotid sinus
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47
Q

What is the foramina and function of cranial nerve X?

A

Vagus Nerve

  • Jugular Foramen
  • Branchial motor to muscles of pharynx and larynx, muscles of soft palate
  • Visceral motor to thoracic and GI tract
  • Visceral and special sensory, taste from epiglottis and palate
  • Somatic sensation from epiglottis, skin of external ear and larynx
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48
Q

What is the foramina and function of cranial nerve XI?

A

Accessory Nerve

  • Jugular Foramen
  • Somatic motor to sternocleidomastoid and trapezius
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49
Q

What is the foramina and function of cranial nerve XII?

A

Hypoglossal Nerve

  • Hypoglossal canal
  • Somatic motor to muscles of tongue
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50
Q

What does injury of the hypoglossal nerve present as?

A

Deviation of the tongue to the paralysed side

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51
Q

What muscle and nerve controls closing of the eyelids?

A

Orbicularis oculi

CNVII

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52
Q

What muscles and nerves control the opening of eyelids?

A

Superior tarsal muscle - sympathetic (keep eye open)

Levator palperbrae superioris - CNIII (open eye)

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53
Q

What muscle and nerve controls dilation of the pupil?

A

Dilators of iris - sympathetic

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54
Q

What muscles and nerves control constriction of pupil and sense change?

A

Constriction - sphincter pupillae - CNIII parasympathetic

Change Lens - Cillary muscle - CNIII parasympathetic

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55
Q

Describe the corpus striatum

A

Internal structures of grey matter of each cerebral hemisphere

  1. Globus pallidus
  2. Putamen
  3. Caudate nucleus
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56
Q

What are the hemispheric limbic structures?

A
  • Hippocampus
  • Fornix - contains main efferent fibres of the hippocampus, follows a C shape over the thalamus
  • Amygdala
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57
Q

What are the three classes of fibres in the white matter of cerebral hemispheres?

A

Association fibres - interconnect areas within a hemisphere and adjacent gyri
Commissural fibres - interconnect areas between hemispheres
Projection Fibres - Interconnect cerebrum with rest of CNS, corona radiata

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58
Q

Describe the internal capsule

A
  • Passes between head of caudate and lentiform nuclei

- Connects to crus cerebri anterior part of pons and medulla pyramids

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59
Q

What are the medial sulci and gyri?

A
  • Cingulate sulcus and gyrus
  • Pareto-occipital sulcus
  • Calcirine sulcus
  • Collateral sulcus
  • Parahippocampal gyrus
  • Uncus
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60
Q

Describe uncal herniation

A

Herniates under tentorium cerebelli and compresses the midbrain
- Tonsil of cerebellum herniate through foramen magnum and compress the medulla oblongata

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61
Q

Describe the primary projection areas

A 
Sensory -
General sensation - post central gyrus 
Visual - either side of calcimine sulcus and occipital pole 
Auditory - heschl's gyrus 
Olfactory - uncus
Gustatory - Inferior post central gyrus 
Motor - 
primary motor cortex - pre central gyrus
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62
Q

Describe the association secondary areas

A

Sensory -
General sensation - superior parietal lobe
Visual - pre striate area
Auditory - lateral fissure/superior temporal gyri
Motor -
Premotor area - anterior to pre central sulcus on lateral surface
Supplementary motor area - anterior to pre central sulcus on medial surface
Frontal eye field - anterior to premotor

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63
Q

What does the primary motor cortex control?

A

Voluntary contraction of specific muscles

- Somatotopically organised

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64
Q

What is cerebral dominance ?

A

Two language areas are located within dominant hemispheres

65
Q

What is motor/non-fluent aphasia?

A

Inability to correctly articulate speech

Broca’s area

66
Q

What is sensory/fluent aphasia and the area of the brain associated?

A

Inability to understand language

Wernicke’s area

67
Q

What is conduction aphasia?

A

Impaired repetition, comprehension and fluency intact

68
Q

How many of each vertebrae are in each segment of the vertebral column?

A 
7 cervical 
12 thoracic 
5 Lumbar 
5 Sacral (fused to form he sacrum)
3-4 fused to form the coccyx
69
Q

What does the spinal cord terminate as?

A

Conus medullaris + filum terminale extends and attaches to the coccyx - made up of arachnoid and dura mater

70
Q

Describe the spinal nerve and vertebral levels relationship

A
  • Cervical segment all nerves emerge above the corresponding vertebrae except C8 which emerges above T1
  • Thoracic segment all nerves emerge below their corresponding vertebrae
71
Q

Describe the marginal zone nucleus, its cord level, lamina and function

A

Cord - all
Lamina - 1
Function - spinothalamic tract cells

72
Q

Describe the substantia gelatinosa nucleus, its cord level, lamina and function

A

Cord - all
Lamina - 2
Function - pain and temperature

73
Q

Describe the proprius nucleus, its cord level, lamina and function

A

Cord - all
Lamina - 3-4
Function - general sensory

74
Q

Describe the intermedia lateral nucleus, its cord level, lamina and function

A

Cord - T1-3 and S2-4
Lamina - 7
Function - sympathetic neurones and parasympathetic neurones

75
Q

Describe the Clarkes nucleus, its cord level, lamina and function

A

Cord - C8-L3
Lamina - 7
Function - dorsal spin-cerebella tract cells

76
Q

Describe the motor nuclei, its cord level, lamina and function

A

Cord - all
Lamina - 9
Function - motor neurones

77
Q

Describe the phrenic nucleus, its cord level, lamina and function

A

Cord - C3-5
Lamina - 9
Function - motor diaphragm

78
Q

Describe the accessory nucleus, its cord level, lamina and function

A

Cord - medulla - C5
Lamina - 9
Function - motor SCM and trapezius

79
Q

Describe the C1-C2 atypical vertebrae

A

C1 articulates with occiput - allows nodding of head up and down
C1-C2 - articulate with each other and form a pivot joint - allows head to turn from side to side

80
Q

Describe hangman’s fractures

A

C2 fracture - can be caused by hyperextension of the head

  • Bilateral fracture of the pars interarticularis
  • Body of C2 can be displaced anteriorly
  • Likely injury to brainstem or spinal cord
81
Q

Describe upper motor neurones

A
  • Originate in the cerebrum and subcortical structures
  • Influence LMN activity
  • modify local reflex activity
  • Superimpose more complex patterns of movement
82
Q

Describe lower motor neurones

A
  • Originate from the brainstem and spinal cord - ventral grey horn
  • peripheral nerves to motor end plates/neuromuscular junctions
83
Q

What are the 3 main descending motor pathway ?

A

Pyramidal corticospinal
Corticobulbar/corticonuclear
Extrapyramidal

84
Q

Describe the corticospinal and corticonuclear pathways

A 
Cerebral cortex
Precentral gyrus 
Internal capsule 
Basal ganglia 
Basal pons 
Pyramids 
Pyramidal decussation - 85% of fibres
Brainstem/spinal cord 
- some will exit spinal cord at level of innervation to provide bilateral innervation

More anterior corticospinal pathway - less decussation

85
Q

Describe the internal capsule lesion

A
  • Vulnerable to vascular damage
  • Small end arteries at risk in hypertension
  • Main important sensory and motor fibres in small area
86
Q

Describe the reticulospinal pathway

A
  • Reticular formation - pons and medulla to spinal cord

- Controls voluntary movement/breathing/consciousness

87
Q

Describe the vestibulospinal pathway

A

Vestibular nuclei - pons and rostral medulla to spinal cord - anterior horn
- Controls posture

88
Q

Describe rubrospinal pathway

A

Red nucleus - midbrain to spinal cord

- controls muscle tone

89
Q

Describe the 3 neurones chain

A

1st neurone - pseudo unipolar - cell body in sensory ganglion DRG or CN ganglion
2nd neurone - axon crosses midline ascends to ventral posterior thalamus - travels up contralateral side to thalamus
3rd neurone - axon projects to post central gyrus - parietal lobe - relay to primary sensory cortex

90
Q

What are the 3 trigeminal nuclei and their function?

A

Mesencephalic - proprioception
Pontine - discriminative touch
Spinal - simple touch, pressure, pain and temperature

91
Q

Describe the pathway for pain and temperature

A
  • Primary cell bodies in trigeminal ganglion

- secondary axon crosses and ascends in trigeminothalamic tract to thalamus

92
Q

Describe the pathway of crude touch and pressure

A
  • Primary cell bodies in trigeminal ganglion
  • Some fibres descend in spinal tract of trigeminal nerve
  • Some fibres synapse with secondary neurones more rostrally in spinal nucleus
  • axons cross and ascend in trigeminothalamic tract to thalamus
93
Q

Describe the pathway for discriminatory touch

A
  • Primary neurone cell bodies in trigeminal ganglion
  • Synapses with secondary in pontine chief nucleus
  • Axon crosses and ascends in trigeminothalamic tract to thalamus
94
Q

Describe the proprioception pathway

A
  • Primary neurone cell bodies in mesencephalic nucleus
  • Primary axons travel in the mandibular division of trigeminal to thalamus
  • Secondary axon crosses and ascends to thalamus in trigeminothalamic tract
95
Q

Describe the spinal reflex as a basis for motor control

A
  1. Sensory receptor fires action potential upon stimulus
  2. Sensory neurone carries action potential to spinal cord
  3. Integration centre - relay sensory to motor
    - can be monosynaptic or polysynaptic
  4. Motor Neurone
  5. Effector organ
96
Q

Describe the myotatic stretch reflex with regard to the patellar tap reflex

A
  1. Tap quadriceps tendon and stretch of quadriceps muscle
  2. Activation of the muscle spindle and increased firing of a 1a afferent
  3. Afferent terminals synapse directly with and excite the alpha motor neurone
  4. Increased alpha motor neurone efferent axon activity
  5. Contraction of the agonist homonymous muscle - ie muscle from which afferent arose
97
Q

Describe the inverse myotactic stretch reflex (Golgi reflex)

A

Controls the tension of an active muscle in response to muscle contraction to avoid tendon damage

  • Tension feedback and overload protection
    1. Golgi tendon organ excitation
    2. Increasing firing in 1b afferent
    3. Indirect inhibition via an inhibitory interneuron of the alpha motor neurone
    4. Decreased alpha motor neurone activity to homonymous muscle
    5. Relaxation/inhibition of the homonymous muscle
98
Q

Describe the crossed extensor/flexor withdrawal reflex

A

Noxious (Harmful/unpleasant) cutaneous stimulation causes flexion withdrawal from the offending stimulus. Simultaneous extension of contralateral limb may occur for weight bearing
- Damage limitation of avoidance, maintained balance on limb withdrawal
1. Increased activity in A-delta & C afferents
2. Polysynaptic activation of ipsilateral flexors
3. Polysynaptic inhibition of ipsilateral extensors
4. Polysynaptic inhibition of contralateral flexors
5. Polysynaptic excitation of contralateral extensors
Enables automatic maintenance of balance during reflex

99
Q

What are the layers of the skin?

A

Epidermis - keratin producing squamous epithelium
Dermis - papillary dermis and reticular dermis
Subcutis - adipose tissue

100
Q

What are the 5 layers of thick skin?

A 
Basal layer - stratum basal 
Prickle cell layer - stratum spinosum 
Granular layer - stratum granulosum 
Stratum lucidum - skin of the sole 
Keratin layer - stratum corneum
101
Q

What are the cells found in the epidermis?

A

Keratinocytes
Melanocytes
Langerhans cells

102
Q

Describe the 4 skin receptors

A

Meissner Corpuscles - touch and vibration
Merkel cells - slow adopting touch and pressure
Pacinian corpuscles - fast acting vibration
Ruffini endings - vibration and pressure

103
Q

Describe the autonomic nervous system

A

Largely involuntary
Monitors conditions in the internal environment to maintain homeostasis
Influenced Rostrally by the hypothalamus

104
Q

Describe the autonomic motor and sensory fibres of the PNS autonomic division

A

Motor: efferent fibres to smooth muscles, cardiac muscles or glands
Sensory: afferent fibres from sensory receptors in an internal organ - responsible for referred pain
Only carried within segmental spinal nerves T1-L2 and S2-S4

105
Q

Describe the parasympathetic division of the autonomic nervous system

A

Cranio-sacral origin - brainstem and S2-S4- lateral cord of sacral grey horn
Acetylcholine
Localised effects

106
Q

What 4 cranial nerves do parasympathetic fibres run?

A

III - to constrict pupil
VII - to salivary glands and lacrimal glands
IX - to salivary glands
X - to cardiac pulmonary and digestive systems

107
Q

Describe the sympathetic division of the ANS

A
  • Thoracic-lumbar origin T1-L2 spinal segments
    Pre: acetylcholine
    Post: noradrenaline except sweat glands
    Widespread Effects - neuronal divergence and adrenal medulla
108
Q

What level do all preganglionic fibres leave cord in segment spinal nerves ?

A

T1-L2 only

109
Q

Describe the role of the hypothalamus in the ANS

A
  • Controlling influence upon the activity of the ANS
  • Central role in neuroendocrine function via connections with pituitary
  • Important connections with the limbic systems
110
Q

Describe the spinal reflex path

A
  1. Sensory receptor - fires action potential upon stimulus
  2. Sensory neurone - carries action potential to spinal cord
  3. Integration centre - relay sensory to motor
    Can be monosynaptic or polysynaptic
  4. Motor neurone
  5. Effector organ
111
Q

Describe the myotatic stretch reflex and run through the sequence of events in relation to the quadriceps muscle

A

Muscle contraction, in response to stretching within the muscle

  1. Tap quadriceps tendon and stretch quadriceps muscle
  2. Activation of the muscle spindle and increased firing of a 1a afferent
  3. Afferent terminals synapse directly with and excite the alpha motor neurone
  4. Increased alpha motor neurone efferent axon activity
  5. Contraction of the agonist homonymous muscle
112
Q

Describe the antagonist response of the myotatic stretch reflex

A

direct excitation of motor neurones and indirect inhibition via the 1a inhibitor interneuron of motor neurones innervating antagonist

113
Q

Describe the inverse myotatic stretch reflex (Golgi tendon reflex)

A

Control the tension of an active muscle in response to muscle contraction to avoid tendon damage

  1. The Golgi tendon organ excitation
  2. Increased firing in 1b afferent
  3. Indirect inhibition via inhibitory interneuron of the alpha motor neurone
  4. Decreased alpha motor neurone activity to homonymous muscle
  5. Relaxation/inhibition of the homonymous muscle
114
Q

Describe the crossed extensor/flexor withdrawal reflex

A

Noxious cutaneous stimulation causes flexion withdrawal from the offending stimulus
- Simultaneous extension of contralateral limb may occur for right bearing
Damage limitation of avoidance
Maintained balance on limb withdrawal
1. Increased activity in A-delta and C afferents
2. Polysynaptic activation of ipsilateral flexors
3. Polysynaptic inhibition of ipsilateral extensors
4. Polysynaptic inhibition of contralateral flexors
5. Polysynaptic excitation of contralateral extensors
Enables automatic maintenance of balance during the reflex

115
Q

What are the functions of the cerebellum?

A
  • Production of coordinated movements
  • Maintain equilibrium balance and posture
  • Coordinates appropriate time force and duration of muscle contraction
  • Store instructions for patterns of movements
  • Linguistic and cognitive functions
  • Cerebellum acts ipsilaterally
116
Q

Describe the vestibulocerebellum

A

Comprises flocculonodular lobe and part of vermis

- Coordinates muscles involved in maintaining balance and consistency of visual fields

117
Q

Describe the spinocerebellum

A

Comprises most of vermis and adjacent region of hemispheres

- co-ordinates muscles involved in posture and locomotion

118
Q

Describe cerebrocerebellum

A

Lateral parts of cerebral hemispheres

- Coordinates movements of distal limbs particularly fine, skilled and targeted movements of hands

119
Q

Describe the vestibulocerebellum

A

Regulates balance and eye movements

  • Receives ipsilateral information from balances
  • Associated with vestibular apparatus and nuclei
  • Adjusts muscles and eye movements in response to vestibular stimuli
120
Q

Describe the spinocerebellum

A

Receives unconscious proprioception from Golgi organs/muscle spindle
- Adjusts muscle tone and execution of movements

121
Q

Describe the cerebrocerebellum

A

Control of fine motor skills and targeted movements of limbs particularly hands

  • Receives information on intended movements that are in progress from the cerebral cortex - corticopontine fibres and olivocerebellar fibres
  • Ensures a smooth and orderly sequence of muscle contractions with intended precision, force and direction = particularly important for upper limb activity
122
Q

Describe the cerebellar peduncles and the inputs/outputs

A

Left Side
SCP - output to motor cortex, reticular nuclei and red nucleus
Ensure intended movement coordinated and controlled
MCP - Input from cortex including motor cortex via nuclei in pons
Knows about intended movements
ICP - input from cortex including motor cortex via inferior olivary nucleus
Knows about intended movements

Rights side
knows what muscles are doing
Proprioception and other sensory information from spinal cord passes into the cerebellum via the ICP

123
Q

What are the effects of cerebellar damage?

A

Incoordination or ataxia
Person is still able to move but in disordered manner
A unilateral lesion to cerebellar hemisphere causes symptoms on the ipsilateral side of the body

124
Q

What is truncal ataxia?

A
  • Inability to stand or sit without falling over
  • Midline lesion affecting vestibulocerebellum
  • Most commonly due to medulloblastoma
125
Q

What is gait ataxia?

Where is the most likely lesion to cause this?

A
  • Lower limbs most affected, staggering wide based gait
  • Lesion of spinocerebellum
  • Most common in chronic alcoholics due to degeneration of cerebellar neurone in paranormal areas
126
Q

Describe a lesion in the cerebrocerebellum

A
  • Inco-ordination of voluntary movement particularly in the upper limb
  • Many possible causes
    Tremor of intent
    Past pointing or dysmetria
    Adiadochokinesia
    Dysarthria
127
Q

What are the functions of the three parts of the ear?

A

External: receives sound waves transmitted towards tympanic membrane
Middle: sound waves to mechanical waves
Inner: mechanical waves to electrical waves

128
Q

Describe the middle ear

A
  • Connected to nasopharynx - prone to infection
  • Connected to mastoid air cells - infection may spread to middle cranial fossa
  • Internal jugular vein lies inferior - risk of thrombosis
  • Internal carotid artery lies anterior - link to pulsatile tinnitus
  • Transversed by chords tympani and facial canal - infection risk
129
Q

Describe the inner ear

A
  • Located in petrous part of temporal bone
  • Composed of 2 special sense organs
  • Vestibular system - balance and equilibrium
  • Vestibule and semicircular canals and semicircular ducts
  • Cochlea and cochlear ducts
    Bony outer labyrinth contained with perilymph and membranous inner labyrinth containing endolymph
130
Q

Describe the cochlear and cochlear duct and the two chambers of the cochlear

A

Cochlear duct separates cochlea into two chambers
- Scala vestibuli (SV)
- Scala tympani (ST)
Two chambers are continuous at the apex of the cochlea through a narrow slit - helicotrema
- Fluid (Perilymph) moves around the bony cochlea it deforms the endolymph inside the cochlear duct
Cochlear duct contains spiral organ - tectorial membrane, embedded hair cells

131
Q

Describe the spiral organ of corti

A

Stimulated by the deformation of the cochlear duct by the perilymph in the surrounding SV and ST
- Converts fluid pressure into electrical signals via cochlear nerve

132
Q

Describe the auditory pathway

A

Cochlea
Cochlear nerve to cochlear nuclei
Superior olivary nuclei (receives bilateral auditory information)
through mid pons, pons-midbrain junction to inferior colliculus (receives lateral reminisces)
To medial geniculate nucleus - auditory cortex

133
Q

Describe the tonotopic organisation of the cochlea and auditory cortex

A

Different regions of the basilar membrane respond to sounds of different pitch
Low frequency = anterolateral
High frequency = posteromedial part

134
Q

Describe Broca’s area and wernicke’s area

Function and blood supply

A

Brocas: anterior
Motor production of words
Blood supply - upper anterior division of middle cerebral artery
Wernicke’s: posterior
Sensory understanding
Blood Supply - lower posterior division of middle cerebral artery

135
Q

Describe the areas of the retina

A

Neural layer
Optic nerve
Optic disk
Macula + fovea

136
Q

Describe the nerve cell types as part of the retina

A

Optic nerve = ganglion cells
Bipolar cells - linking photoreceptors to ganglion cells
Cones and rods

137
Q

Describe rods and cones in the eye

A 
Rods
- 20x more common
- Sensitive to light 
- Vision in dim light 
- High level convergence 
Cones - many In fovea
- Colour vision
- High visual acuity 
- Lower level of convergence 
- At macula one cone to one ganglion cell
138
Q

Describe papilloedema

A
  • Swelling of optic disc
  • Optic nerve is surrounded by the meninges
  • Increases CSF pressure can swell the optic nerve
  • Increase in pressure compresses the central retinal vein preventing venous drainage from the eye
    Symptoms: head-aches, drowsiness, blurred vision and vomiting
139
Q

Describe the calcarine sulcus and surrounding area

A

Calcarine sulcus - primary visual cortex lies above and below
Above - parietoccipital sulcus - visual association
Below - visual association area

140
Q

Describe the visual pathway

A
  • Left half of visual field goes to right hemisphere
  • Right Half of visual field goes to left hemisphere
  • Upper visual field goes to lower bank of calcimine sulcus
  • Lower visual field goes to upper bank of calcimine sulcus
    Centre of visual axis (macula) goes to occipital pole
141
Q

Describe the retinotopic mapping of the optic chiasm and optic radiations

A

Temporal fibres = closest to temporal bone
Nasal fibres = fibres closest to nose (inner)
Left half of visual field goes to right hemisphere
Right half of visual field goes to left hemisphere
Superior trajectory - lower visual fibres
Inferior trajectory/meyers loop - upper visual field fibres

142
Q

What is a scotoma, anopia, homonymous and heteronymous?

A

Scotoma - localised patches of blindness
Anopia - refers to the loss of one or more quadrants of the visual field
Hemi - half of the visual field is lost
Quad - quarter of the visual field is lost
Homonymous - visual field losses are similar for both sides
Heteronymous - visual field losses are on different sides

143
Q

What is the pupillary light reflex?

A

The ability of both pupils to respond dependent on the level of light the retina receives
- Utilises two cranial nerves oculomotor and optic

144
Q

What is the accommodation reflex?

A

Series of changes that occur when the gaze is transferred from a distant to near object

  1. Accommodation - ciliary muscles contract - lens becomes rounded
  2. Pupil constricts - sphincter pupilae
  3. Ocular convergence - medial rectus
145
Q

What is the primary function of the basal ganglia?

A

To provide a feedback mechanism to the cerebral cortex for initiation, control and cessation of motor response

  • Relays decision to move through thalamus
    1. Excite cerebral cortex: facilitate wanted movement
    2. Dampen cerebral cortex: inhibition of unwanted movement
146
Q

What do lesions in the basal ganglia cause?

A

Dyskinesia - abnormal involuntary movements

147
Q

What are the functional basal ganglia?

A 
Corpus striatum - 
Caudate nucleus + putamen 
Globus pallidus 
Substantia nigra 
Subthalamic Nucleus
148
Q

Describe the afferent connections of the basal ganglia

A

Input nuclei - striatum

  • From the cortex - corticostriatal fibres information about intended movement
  • From substantia nigra pars compacta - nigrostriatal fibres release dopamine
149
Q

Describe the efferent connections of basal ganglia

A

Output nuclei - GPi + Sir - send efferent fibres to supply the thalamus - pallidothalamic fibres - inhibitory - inhibit the thalamus

150
Q

Describe the intrinsic connections of basal ganglia

A

Direct - facilitate a specific movement programme - neurones from the striatum that project to GPi directly
Indirect - inhibit a specific movement programme, allow direct pathways programme - neurones from the striatum that project to GPe, from the GPe neurones project strongly to the subthalamic nucleus which later projects back to GPi

151
Q

What is the role of the substantial nigra pars compacta?

A

Release dopamine - has modularity role in the direct and indirect pathways - main function to initiate movement

152
Q

Disruption of what leads to Parkinson’s disease?

A

Nigrostriatal input

- Most common disease of basal ganglia

153
Q

What are the limbic structures?

A 
HOME 
Hypothalamus - homeostasis 
Paraolfactory area - olfaction 
Amygdala - emotions 
Hippocampus - memory
154
Q

What is the cingulum?

A

Receiver of information from pre-frontal, parietal, occipital and temporal gyri - association fibres
Involved in formation of memories and emotions

155
Q

Describe the amygdala

A

Almond shaped nuclear complex in the medial temporal lobe - deep to uncus - mainly involved in emotions and behaviour

156
Q

Describe hippocampal formation and its functions

A

Nuclear complex in the medial temporal lobe

  • deep to parahippocampal gyrus
  • Mainly involved in memory - short term
  • Formation of new memories and learning
  • Damage leads to inability to recall recent events
157
Q

What are the stria terminals?

A

Band of fibres that runs along the ventricular surface of the thalamus

158
Q

Describe the circuit of papez

A

Reinforcement of emotion, memory and olfaction with each other for survival responses
Hippocampus - fornix - maxillary bodies - anterior thalamic nuclei - cingulate gyrus - hippocampus

Year 2 Medicine Leeds (4 decks)

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