Anatomy and Physiology Flashcards

(212 cards)

1
Q

What are the cerebral hemispheres divided by?

A

sulci form lobes which are part of the hemispheres formed by gyri

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2
Q

What are:

Sulci?

Gyri?

A

Groove on brain

Ridge-like elevation

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3
Q

List the lobes of the brain.

A
  • Frontal
  • Parietal
  • Occipital
  • Temporal
  • Limbic
  • Insula
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4
Q

List the regions of the CNS (4). Give specific parts of each region.

A
  1. Spinal cord 
 

  2. Brainstem (nuclei of all CN bar CN I + CN II)
    
a) Medulla 

    b) Pons
    
c) Midbrain 


  3. Cerebellum



4. Cerebrum


a) Telencephalon (cerebral hemispheres)

b) Diencephalon (thalamus + hypothalamus)

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5
Q

What are the two main appearances of the CNS?

Where are they located in:

i) The Brain
ii) The Spinal Cord

A

1) Grey Matter: Cell bodies of neurones + neuroglia + unmyelinated neurones
• Nucleus (CNS)
• Ganglion (PNS)
• Surface of cerebral and cerebella hemispheres

Locations:
• Brain: Grey matter outside
• Spinal cord: Grey matter in centre

2) White Matter: Axons of myelinated neurones.

Locations:
• Brain: White matter is central
• Spinal cord: White matter is peripheral

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6
Q

What are meninges?

List the meningeal layers.

A

Membranes which protect the encephalon and spinal cord in addition to bones and vertebra and cerebrospinal fluid

1) Dura mater: superficial and toughest meninges layer which has two layers: outer periosteal layer and inner meningeal layer. Apart from the dural sinuses, these two layers are in apposition.
2) Arachnoid mater: Middle layer, adhered closely to the dura with a web-like appearance
3) Pia mater: Deepest layer which is in direct contact with CNS tissue (encephalon + spinal cord) which is highly vascular and enters every sulci

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7
Q

What is the term for the inward layer of dura delving to divide the brain into two hemispheres?

What does this allow functionally?

A

Falx cerebra: Inward septa of dura (Dural partitions)

Brain secured to skull (periosteum connected to outer meninges)

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8
Q

Which is the innermost layer of the meninges, in direct contact with CNS tissue?

A

Pia mater

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9
Q

What is a meningeal space?

List the 3 meningeal spaces.

A

Spaces between meningeal layers

1) Epidural space: Potential space of Dura mater to Bone
2) Subdural space: Potential space of Dura to Arachnoid
3) Subarachnoid space: Real space containing CSF + Cerebral arteries between Arachnoid and Pia mater

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10
Q

What is the term for the two external invaginations and evaginations of the cerebrum?

A

1) Gyri (gyrus): Rises

2) Sulci (sulcus): In-folding

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11
Q

Give the term of the sulcus separating the brain into two cerebral hemispheres.

A

Median longitudinal fissure is a sulcus separating the two cerebral hemispheres

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12
Q

List three identifiable regions of Dural septa.

A

Tentorium cerebelli

Tentorial notch

Falx cerebelli

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13
Q

Outline the two divisions of the ANS.

Give:

  • Outflow
  • Pre-ganglionic NT
  • Post-ganglionic NT
  • Effects
A

1) Sympathetic
• Thoracolumbar
• Pre-ganglionic sympathetic neurons: T1-L2 spinal cord (thoracolumbar)
• Ganglia in sympathetic chain
• Pre-ganglionic NT: ACh @ Nicotinic
• Post-ganglionic NT: NE @ Adrenergic (NB: Sweat gland is ACh and Adrenal Medulla)
• Effects: Mydriasis, tachycardia, vasoconstriction, tachypnea, bronchodilation, glycogenic, diaphoresis

2) Parasympathetic
• Craniosacral
• Pre-ganglionic parasympathetic neurons: brainstem + S2-S4
• Pre-ganglionic NT: ACh @ Nicotinic
• Post-ganglionic NT: ACh @ Muscarinic (PAM)
• Effects: Meiosis, GI motility (peristalsis), glandular secretion, excretion (defaecation) and micturition

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14
Q

Outline the embryological development of the nervous system (spinal cord).

A

• Ectoderm -> Neural plate -> Neural tube closes -> Neural crest cells give rise to NS cells: Melanocytes, Schwann Cells, Adrenal medullary cells, dorsal root ganglion cells, autonomic ganglion cell

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15
Q

What germ layer is the neural tissue derived from?

A

Ectoderm

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16
Q

List 3 types of glial cells and their functions.

A

• Oligodendrocytes: myelination formed by these cells which is a spiral multi-layered wrapping of glial membrane increasing AP conduction speed by restriction of ionic current to smaller unmyelinated portions at nodes of Ranvier
- 1 oligodendrocyte to many myelinated CNS axons
• Microglial cells: Immune responses within CNS removing cellular products by phagocytosis assisted by other glia and phagocytes invading CNS from circulation
• Astrocytes: named by morphology with cell body and several branches arising which produces BBB, regulates the CNS microenvironment by buffering EC environment with ions and NTs, local astroglia take up excess K+, post-injury astrocytes ∆ to become reactive astrocytes forming glial scar (segregating damaged tissue) and couples GAP junctions to form sanctum for small molecules and ions to redistribute along concentration gradients or by current glow.
• Ependymal cells: epithelium lining ventricular spaces of the brain which secretes CSF in ventricular system where the substance diffuses readily across ependymal lining between EC space of brain and CSF
• Satellite cells: encapsulate dorsal root and cranial nerve ganglion cells regulating microenvironment like astrocytes

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17
Q

List 3 features of a neurone.

A

1) Dendrites: branching extensions of soma which expands SA of neurone to receive signals from other neurones which can be primary or higher-order. Individual dendrites aggregate into dendritic trees ≈ ∆ between different neurone types, size, number and spatial organisation
2) Soma (cell body): core of neurone bearing genetic and metabolic centres of neurones” nucleus, nucleolus, Nissl bodies (neuronal biosynthetic apparatus ≈ RER + Golgi Body), mitochondria, cytoskeletal elements). Soma receives synaptic input from dendrites



3) Axon: extension of cell body, as proximal dendrite in specialised region called axon hillock, conveying output of cell to other neurones with variable length and diameter ∆s according to neuronal type. Axon is absent of RER, free ribosomes and Golgi apparatus. Axon may terminate in a synapse and may make synapses along its length. 


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18
Q

List 3 types of neurone based on polarity.

A
  1. Multipolar neurone: Most abundant in CNS where dendrites branch directly of soma and single axon arises from axon hillock


  2. Pseudounipolar neurone: Spinal ganglion with dendritic axon receiving sensory information from periphery sending to spinal cord via an axon bypassing cell body along the way ≈ relay sensory information from peripheral receptor to CNS w/o modifying signal 


  3. Bipolar neurone: retina and olfactory epithelium with main dendrite receiving synaptic input conveyed to cell body and from there through axon to next layer of cells. Bipolar neurones integrate multiple inputs and then bypasses modified information to next neurone in the chain. Difference between pseudounipolar and bipolar neurone ≈ amount of processing occurring in neurone
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19
Q

What is radial migration?

A
  • Cells migrate along radial glia from origin in ventricular and subventricular zones –> formation of cortex and deep nuclear structures
  • Radial migration gives rise to projection neurons of the cortex
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20
Q

List the 4 lobes of the brain and their main functions.

A

1) Frontal lobe: Motor functions and Personality and ability to change; ‘frontal lobe personalities’
2) Temporal lobes: Memory and speech (L > R)
3) Parietal lobe: Spatial awareness ( R ), Language (L)
4) Occipital lobes: Vision

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21
Q

Which lobe of the brain is primarily responsible for motor functions and personality?

Give one way you can test this.

A

Frontal lobe: Motor functions and Personality and ability to change; ‘frontal lobe personalities’
• Sequencing and fluency

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22
Q

Which lobe of the brain is primarily responsible for memory and speech?

Which hemisphere are these features more dominant in for a Right Handed person?

How would you test this?

A

Temporal lobes: Memory and speech (L > R)

L > R

Test(s):
• Address test: Give a pseudo address and see if they remember it
• Object recall
• Serial 7s

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23
Q

Which lobe of the brain is primarily responsible for spatial awareness and language?

Which hemisphere are these features more dominant in for a Right Handed person?

How would you test this?

A

Parietal lobe: Spatial awareness ( R ), Language (L)

Right side is awareness

Left side is Language

Tests:
•	Clock face: Put numbers on and draw ten to two, neglecting one side of space, put all on one side 
•	Naming objects 
•	Drawing cube, interlocking infinity
•	Agnosia
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24
Q

Which lobe of the brain is primarily responsible for vision.

A

Occipital lobes: Vision

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25
Outline the visual field pathway explaining the route of neuronal transmission.
• Light -> photoreceptors (rods and cones) -> retinal ganglion cells -> leaves orbit via optic canal (passageway between sphenoid bone) -> enters cranial cavity running along surface of middle cranial fossa -> optic nerves from each eye unite ≈ optic chiasm -> fibers from nasal (medial) half of each retina cross over to contralateral optic tract whilst temporal (lateral) halves remain ipsilateral -> Optic tract (L+R) -> synapse in lateral geniculate nucleus (LGN) relay system in thalamus -> axons from LGN carry visual information in optic radiation pathway (upper optic radiation and lower optic radiation) -> i) Upper optic radiation: Fibres from superior retinal quadrants (correspond to inferior visual field quadrants) travel through parietal lobe to reach visual cortex ii) Lower optic radiation: Fibres from inferior retinal quadrants (correspond to superior visual field quadrants) travel through temporal lobe via Meyers’ loop pathway to reach visual cortex
26
List the three parts of the brainstem.
* Midbrain * PONS * Medulla
27
Which muscles contribute to depression of the eyeball? Give their innervations.
Inferior rectus (III) Superior oblique (IV)
28
What muscles contribute towards medial rotation of the eyeball. Give their innervations.
Medial rectus (III) Superior Oblique (IV)
29
What muscles contribute towards lateral rotation of the eyeball. Give their innervations.
Lateral rectus (VI) Inferior Oblique (III)
30
What muscles contribute towards elevation of the eyeball. Give their innervations.
Superior Rectus (III) Inferior Oblique (III)
31
What muscles contribute towards adduction of the eyeball. Give their innervations.
Medial rectus (III) Superior rectus (III) Inferior rectus (III)
32
What muscles contribute towards abduction of the eyeball. Give their innervations.
Lateral rectus (VI) Superior oblique (III) Inferior oblique (III)
33
Give the Tract and Nuclei in the medial brainstem.
* Medial lemniscus (X) * Motor tracts – somatic (X) * Median Longitudinal Fasciculus (X) * Motor N – somatic
34
Give the Tract and Nuclei in the lateral brainstem.
* Spino-cerebellar (I) * Spino-thalamic (X) * Sympathetic (I) * Somatic sensory
35
What is the dermatome of the umbilicus?
T10
36
What is the dermatome of the middle finger?
C7
37
What is the dermatome at the level of the nipples?
T4
38
What region of the spinal cord roots are mainly sensory?
Dorsal root
39
What region of the spinal cord roots are mainly motor?
Ventral root
40
Give 3 conditions affecting the spinal cord.
- B12 deficiency - HIV Myelopathy - Tabes dorsalis - Multiple Sclerosis
41
Give the pathway that is responsible for pain and temperature.
Spinothalamic tract
42
Give the pathway that is responsible for proprioception (conscious)
Dorsal-column medial lemniscus pathway
43
Give the pathway that is responsible for light touch.
Dorsal-column medial lemniscus pathway
44
Give the pathway that is responsible for unconscious proprioception.
Spinocerebellar tract
45
Give the pathway that is responsible for motor function to the body.
Corticospinal tract
46
Give the pathway that is responsible for motor function to the face.
Corticobulbar tract
47
Give the three main stages of drinking a glass of wine regarding execution of motor function.
Sensory integration Planning Execution
48
Outline the route of the corticospinal tract.
Primary motor cortex --> Descending fibres (from corona radiata) pass through internal capsule --> descend through 3/5 crus cerebri in anterior midbrain --> break into bundles in Pons --> 90% fibres decussate (lateral corticospinal tract) h/e 10% descend ipsilateral (anterior corticospinal tract) --> Lateral CST terminates as LMNs in anterior horn of spinal cord cf Anterior CST cross midline at level terminating on LMN
49
Give the two divisions of the corticospinal tract. What is the fundamental difference between these two?
Anterior Corticospinal Tract (decussates at level of LMN) | Lateral Corticospinal Tract decussates in Medulla Oblongata
50
Give the features of an UMN Lesion.
* Increased tone * Weakness: Hemiplegia (arm extensors weaker than flexors; flexors weaker than extensors in leg thus Legs are extensors and Arms are Flexors) * Reflexes exaggerated * No fasciculation * Babinski reflex
51
Give the features of a LMN Lesion.
* Weakness * Atrophy * Reduced reflexes * Fasciculations * Negative Babinski sign
52
How much protein is usually present in CSF?
No protein
53
Where is CSF derived from?
Plasma
54
What is the rough volume of CSF? A. 80-110ml B. 40-70ml C. 120-150ml D. 160-190ml
C. 120-150ml
55
How much CSF is produced roughly in a day?
500ml 25ml per hour
56
Where is CSF produced?
• Produced by ependymal cells in choroid plexus + some may filter through ventricular lining
57
Where is CSF absorbed?
• Reabsorbed in arachnoid granulations in venous sinsuses and nasal lymphatics
58
How much WBC is usually present in CSF?
< 5/ml
59
How much glucose is usually present in CSF?
60-70% cf blood 2.5-5.0mmol/L
60
List 3 functions of CSF.
* Buoyancy (weighs less) * Protection: soft gel in hard box * Waste clearance * Homeostasis * Intracranial pressure regulation * Immune surveillance
61
Outline the route of CSF fluid movement from site to exit. State each anatomical region where the CSF route passes through.
set of four interconnected cavities in the brain where CSF is produced (choroid plexus bearing ependymal cells). 1) Lateral ventricle @ cerebral hemisphere 2) Central ventricle @ spinal cord 3) 3rd ventricle @ Diencephalon via aqueduct 4) 4th ventricle @ Brain stem 5) Arachnoid Granulations (in venous sinuses): Reabsorbed
62
Outline the key points for a Lumbar Puncture. Focus on: - Position - Anaesthetic - Site of puncture - Reading
* Lying left lateral with legs flexed at knee and pulled towards their chest (foetal position) * Clean with iodine + inject with anesthetic * Feel for ASIS (L3/L4) * Lumbar puncture needle, withdraw central core * Connected to manometer
63
Give the range of readings for opening pressure in a lumbar puncture.
* OP <20cm = normal OP * 21-29 = intermediate * > 30 cm water = elevated
64
Give 3 complications of a lumbar puncture.
* Headache: Low pressure headache, worse standing up, eased lying down, N+V * Bleeding/bruising * Nerve damage * Infection * Coning/Death
65
Should hydrocephalus occur in a person with unfused cranial sutures, what might happen?
Expanded cranium
66
Should hydrocephalus occur in a person with fused cranial sutures, what might happen?
Raised intracranial pressure in a fixed cranium
67
Give 3 general causes of elevated CSF.
* Infections * Inflammation * Tumours: Malignant meningitis * Vascular
68
Mrs. X, a 54 year old woman presents with headache, visual disturbances and double vision. O/E you identify she has a BMI of 28 and an ophthalmoscope shows papilloedema. Outline the risk factors this patient has. What is the medical term for double vision? Suggest two investigations you may wish to order. Should raised pressure be identified, what is your DDx? Outline the management plan for this patient. Give two interventions you can do to physically remove the CSF.
- Female - Overweight Double vision = Diplopia - MRV - MRI - LP Raised LP (30-40) DDx: Idiopathic Intracranial Hypertension Management: • Supportive: Weight loss and analgesics • Acetazolamide: reduce production of fluid in the eye (CA inhibitor) * Repeated LP: Remove some of the CSF * Shunt: Ventriculoperitoneal shunt Interventions: • Repeated LP: Remove some of the CSF • Shunt: Ventriculoperitoneal shunt
69
What is syringomyelia?
= fluid-filled cavity or cyst (syrinx) forms within spinal cord. Expanding syrinx compresses and destroys surrounding nervous tissue.
70
A 50 year old male presents with muscle weakness, neck and shoulder pain and stiffness in the leg. O/E you notice Ataxia and Scoliosis as well as Numbness in several regions. What investigation would you order? The radiologist identifies a fluid-filled cavity in the spinal cord. What is this sign/radiological feature called? What is your DDx.
MRI: Chiari malformation Management: • Supportive
71
Define sleep.
• Sleep = easily reversible state of inactivity with lack of interaction with environment
72
Define consciousness.
• Consciousness = awareness of surroundings
73
Define unconsciousness.
• Unconsciousness = depressed state of neural activity/absence of wakefulness/sleep
74
State the two forms of sleep and their main difference.
1) REM: Eyes move rapidly | 2) Non-REM (Slow wave/Deep wave): Eyes do not move rapidly
75
Which investigation can be used to investigate a patient's sleep patterns/features.
Investigation: Electroencephalogram (EEG) • Post-synaptic activity of synchronized dendritic activity picked up from surface • EEG electrodes arranged in 19 ≤ pairs at points of head with EEG leads leading back to detector/transducer • Montage (pile of EEG leads) • Interpretation: Frequency of wave, where they come from and context
76
How many EEG electrodes are used in an EEG and where are they placed generally?
19 pairs of EEG electrodes placed at the surface picking up post-synaptic activity
77
List the types of adult brain waves detected on an EEG during sleep.
* Delta (< 3.5Hz): Deep sleep * Theta (4-7Hz): Sleeping * Alpha (8-13Hz): Awake and resting * Beta (14-30Hz): Awake with mental activity
78
Which brain wave is present at 2Hz and what scenario might this be in? A. Alpha B. Theta C. Delta D. Beta
C. Delta (< 3.5Hz): Deep sleep
79
Which brain wave is present at 7Hz and what scenario might this be in? A. Alpha B. Theta C. Delta D. Beta
B. Theta (4-7Hz): Sleeping
80
Which brain wave is present at 12Hz and what scenario might this be in? A. Alpha B. Theta C. Delta D. Beta
A. Alpha (8-13Hz): Awake and resting
81
Which brain wave is present at 19Hz and what scenario might this be in? A. Alpha B. Theta C. Delta D. Beta
D. Beta (14-30Hz): Awake with mental activity
82
What is a Nerve Conduction Study? Give its uses.
speed of electrical impulse moving through nerve * Electrodes over skin over nerve; stimulate with mild electrical impulse and recording * Speed calculated Uses: • Numbness, tingling and continuous pain e.g. Sciatica/Carpal Tunnel Syndrome
83
Give 5 scenarios where a Lumbar Puncture is contraindicated.
* Raised ICP * SOL * Cord compression * Local skin sepsis * High bleeding risk
84
What is a Cerebral Angiography? What might it show.
injection of contrast die into carotid or vertebral arteries via catheter inserted into femoral artery • Shows: Arterial/Venous obstructions/aneurysms/arteriovenous malformations or tumours
85
List the possible investigations you may carry out in a patient presenting with sleep difficulties.
- FBC - U+E - EEG - NCS - LP + CSF Assay - CT ± Angiography - MRI ± Angiography
86
List the Stages of Sleep. Give the types of Waves observed on an EEG for each stage and what occurs in each stage.
0) Awake Eyes closed: • Frequency: 8-13Hz (Alpha wave) ≈ awake and resting • Amplitude: 50uV (low) Eyes Open: • Frequency: 14-60Hz (Beta wave) ≈ awake with mental activity ``` 1) Stage 1 • Duration: 1-5 minutes • Easily roused • Slow rolling eye movement • Some theta waves (4-7Hz) ``` 2) Stage 2 • Duration: 10-15 mins • K complexes and sleep spindles (8-14Hz bursts) ``` 3) Stage 3 • Duration: A few minutes • Harder to rouse + few spindles • Slower frequency • Delta waves (<3.5Hz) ``` ``` 4) Stage 4 • Duration: 15-30 minutes • Deepest sleep ≈ hardest to rouse • Delta waves (<3.5Hz) • High amplitude (> 200uV) • Heart rate and BP lower ``` ``` 5) REM • Fast Beta waves (8-14Hz) • Easier to rouse cf Stage 4 • Dreaming • Low muscle tone ```
87
What type of wave is present when you are awake and eyes are closed?
• Frequency: 8-13Hz (Alpha wave) ≈ awake and resting
88
What type of wave is present when you are in Stage 2 of sleep. How long might this occur for?
* Duration: 10-15 mins | * K complexes and sleep spindles (8-14Hz bursts)
89
What type of wave is present when you are in stage 3 of sleep?
* Slower frequency | * Delta waves (<3.5Hz)
90
What type of wave is present when you are in stage 4 of sleep?
* Duration: 15-30 minutes * Deepest sleep ≈ hardest to rouse * Delta waves (<3.5Hz)
91
What is the Deepest phase/stage of sleep? A. Stage 1 B. Stage 3 C. Stage 4 D. REM
C. Stage 4 * Duration: 15-30 minutes * Deepest sleep ≈ hardest to rouse * Delta waves (<3.5Hz)
92
In REM stage of sleep, what type of waves are seen?
• Fast Beta waves (8-14Hz)
93
Describe the area of the brain primarily responsible for sleep. What are its main NTs.
Brainstem Reticular Formation (RF) * Diffuse collection of 100 neuromodulatory neurone networks spanning three divisions of brainstem * NTs: NE, 5-HT and Ach * Functions: Posture; Respiration; Heart rate; Sleep/Arousal
94
Which area of the brain is primarily responsible for sleep?
Brain Reticular Formation (RF)
95
What is the main relay to and from the cortex from the reticular formation in the brainstem? (Where does it relay information through)
Thalamus
96
What effect would inhibiting thalamus function have on sensory throughput? A. Increase throughput B. Decrease throughput C. No change D. None of the above
B. Decrease throughput
97
During sleep, outline the neuronal control of Non-REM Sleep.
* Synchronized cortical slow waves due to hyperpolarized thalamus and decreased activity in arousal centers of reticulum * Thalamic cells hyperpolarize further ≈ slow wave rhythmicity (due to thalamic interconnections) ≈ block ascending sensory input -> transmit to cortex with waves synchronized across the cortex
98
Are thalamic cells _____ to ensure slow wave rhythmicity? A. Depolarised B. Hyperpolarised C. Polarised D. None of the above
B. Hyperpolarised
99
What effect do hyperpolarised thalamic cells have on ascending sensory input in the cortex.
• Thalamic cells hyperpolarize further ≈ slow wave rhythmicity (due to thalamic interconnections) ≈ block ascending sensory input --> transmit to cortex with waves synchronized across the cortex
100
What is the hormone pivotal in sleep/awake switch circuitry, keeping people awake? A. Melatonin B. Orexin C. Gastrin D. BDNF
B. Orexin
101
Which neurones are most active during wakefulness regarding sleep. A. Anorexigenic B. Orexinergic C. Orexigenic D. None of the above
B. Orexinergic
102
Where is the centre of non-REM sleep promotion in the brain?
Ventrolateral pre-optic nucleus in anterior hypothalamus (VLPO) Releases inhibitory NTs: GABA and Galanin to inhibit ascending neurones to arousal system for wakefulness
103
Outline the process by which the 'awake' hormone mediates wakefulness.
Orexin released from VLPO --> inhibits VLPO via GABA, 5-HT and NA = wakefulness
104
Outline the process by which an area of the hypothalamus mediates inhibition of wakefulness.
VLPO fires ≈ inhibits orexinergic neurons + arousal centers ≈ remove inhibition of arousal center on VLPO + removes excitation from orexinergic neurons ≈ sleep
105
What is the term for the transition between Orexin-mediated wakefulness and VLPO-driven sleep? A. Tip-tap switching B. Orexin-VLPO transition C. Flip-Flop Switching D. Day-Night Cycling
C. Flip-Flop Switching
106
What daily rhythms influence Flip Flop Switching?
Circadian Rhythms influence the Flip-Flop Switch
107
State the key control region for Circadian Rhythms.
Suprachiasmatic nucleus (SCN) located in hypothalamus and controls: • Circadian cycles (24.5 hours) • Physiological and behavioral rhythms over 24-hour period e.g. sleep-wake cycle
108
What is the term for the stimuli determining the Circadian Rhythm. A. Zussamen B. Umlauchten C. Zeitgeibers D. Entegen
C. Zeitgeibers
109
Outline the process of a Circadian rhythm being programmed.
Process: Light --> melanopsin of photosensitive retinal ganglion cells (≠ rhodopsin/rod cells or photopsin/photoreceptor cells) --> synapse onto SCN directly ≈ reset clock gene
110
What structure separates the cerebral hemispheres? Which meningeal layer is this part of?
Falx cerebri (of dura mater) Dura Mater
111
What is the largest part of the brain?
Cerebrum
112
Which bone does the cerebrum extend from anteriorly to the bone posteriorly?
Frontal bone to Occipital bone
113
Of the cerebrum, which two distinct neuronal regions are there and what are their differences?
* Grey matter: Surface of cerebral hemispheres (cerebral cortex) associated with processing and recognition * White matter: Deeper parts of brain with glial cells and myelinated axons connecting grey matter regions
114
What is a groove of the brain called?
Sulcus
115
What is a ridge or elevation of the brain called?
Gyrus
116
What sulcus divides the cerebrum into two symmetrical hemispheres?
Longitudinal fissure, Falx cerebri descends vertically to fill the fissure
117
What white matter structure connects the two cerebral hemispheres?
Corpus Callosum
118
What sulcus is present between the frontal and the parietal lobes?
Central sulcus
119
What sulcus is present between the temporal lobe and the frontal and parietal lobes?
Lateral sulcus
120
What is the pre-central gyrus?
Anterior to central sulcus which is present in the frontal lobe, responsible for primary motor cortex location
121
What is the post-central gyrus?
Posterior to central sulcus which is present in the parietal lobe, responsible for the primary somatosensory cortex
122
What is the superior temporal gyrus?
Inferior to the lateral sulcus, responsible for perception and processing of sound
123
How many lobes of the cerebrum are there and what are their functions?
4 lobes 1) Frontal: Personality/Social skills/Planning and organising/Problem solving/Flexible thinking 2) Parietal: Perception (Wernicke's Area), Visuospatial awareness, Language 3) Temporal: Memory, Language, Facial recognition 4) Occipital: Sight
124
Outline the arterial supply to the cerebrum.
* Anterior cerebral arteries: Br. Internal carotid arteries --> anteromedial aspect * Middle cerebral arteries: Br. Internal carotid arteries (continuation) --> supply lateral brain * Posterior cerebral arteries: Br. Basilar arteries --> medial and lateral sides of cerebrum posteriorly
125
Outline the venous drainage of the Cerebrum.
* Cerebral veins --> dural venous sinuses (endothelial lined spaces between outer and inner layers of dura mater * Superior cerebral veins --> Superior sagittal sinus * Inferior sagittal sinus * Superior and inferior petrosal sinuses * Transverse and sigmoid sinuses
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What is the Confluence of Sinuses?
The point at which the Superior Sagittal Sinus, Straight Sinus and Transverse and Sigmoid Sinuses join at the occipital protuberance of the skull
127
Personality, emotional and social behaviour is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
C. Frontal
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Planning, organising and movement is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
C. Frontal
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Problem solving and flexible thinking is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
C. Frontal
130
Perception is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
B. Parietal
131
Visuospatial awareness is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
B. Parietal
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Memory is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
A. Temporal
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Facial recognition and word retrieval is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
A. Temporal
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Vision is a feature characteristic of which lobe of the cerebrum? A. Temporal B. Parietal C. Frontal D. Occipital
D. Occipital
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What is the derivation of the cerebellum?
Derived from the rhombencephalon, specifically the mesencephalon
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Which structure is at the same level as the PONS?
Cerebrum
137
What are the 3 lobes of the cerebrum seen sagitally?
Anterior Posterior Flocculonodular
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What are the 3 lobes of the cerebrum seen laterally?
Vermis Intermediate zone (Spinocerebellum) Lateral hemisphere (Cerebrocerebellum)
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What are the 3 functional divisions of the cerebellum?
Cerebrocerebellum Spinocerebellum Vestibulocerebellum
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What is the function of the cerebrocerebellum?
• Planning movements and motor learning
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What is the function of the spinocerebellum?
• Regulate body movements allowing error correction + receives proprioceptive information
142
What is the function of the vestibulocerebellum?
• Controls balance and ocular reflexes (target fixation)
143
Outline the arterial supply to the cerebellum.
* Superior cerebellar artery (SCA): br. Vertebral artery * Anterior inferior cerebellar artery (AICA): br. Basilar artery * Posterior inferior cerebellar artery (PICA): br. Basilar artery
144
Outline the venous drainage of the cerebellum.
• Superior and inferior cerebellar veins --> superior petrosal, transverse and straight dural venous sinuses
145
Give the symptoms of cerebellar dysfunction. Give 3 possible causes of Cerebellar Dysfunction.
* Dysdiadochokinesia/Dysmetria * Ataxia * Nystagmus * Intension tremor * Scanning speech (Dysarthria) * Hypotonia Causes: - Stroke (POCS) - TBI - Tumour - Chronic alcohol excess
146
What is the Basal Ganglia?
numerous subcortical nuclei grouped by function in a feedback circuit cf anatomy which operate in numerous anatomical regions. Basal ganglia are part of a feedback circuit receiving information from sources (e.g. cerebral cortex) --> thalamus --> cortex (via thalamus) = modulate + refine cortical activity (e.g. control descending motor pathways)
147
List the Nuclei of the Basal Ganglia. Categorise them into Input, Intrinsic and Output.
a) Input Nuclei • Caudate nucleus • Putamen Note: Neostriatum = Caudate nucleus + Putamen b) Intrinsic Nuclei • External globus pallidus (GPe) • Subthalmic nucleus (STN) c) Output Nuclei • Internal globus pallidus (GPi) • Pars reticularis of substantia nigra
148
Outline the order of the Basal Ganglia Nuclei from lateral to medial.
Neocortical Insula --> Extreme Capsule --> Claustrum --> External Capsule --> Putamen --> Lateral medullar lamina --> GPe --> GPi --> Internal capsule --> Subthalmic nucleus NECEP GIS
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What is the Claustrum?
thin bundle of gray matter lateral to the external capsule
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What is the Extreme capsule?
white matter tracts lateral to claustrum; separates claustrum from neocortical insula
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What is the External capsule?
white matter fibres lateral to putamen
152
What is the appearance of the Substantia nigra and why is this?
Dark appearance due to neuromelanin in cells of Substantia Nigra pars compacta (SNc)
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What pigment gives the Substantia nigra a dark appearance?
Neuromelanin
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Where is the subthalmic nucleus in relation to: i) Thalamus ii) Substantia Nigra
i) Inferior to thalamus | ii) Superior to Substantia Nigra
155
Outline the blood supply to the Basal Ganglia.
i) Arterial: Middle cerebral artery (br. Internal carotid artery) + Anterior communicating artery (br. Internal carotid artery) * Lenticulostriate artery: Perfusion to lenticular nucleus (globus pallidus and putamen) and striatum * Medial striate artery (of Heubner): Head of caudate nucleus and nucleus accumbens * Posterior communicating arteries: Substantia nigra and subthalamic nucleus
156
Outline the venous drainage of the basal ganglia.
Striate branches of internal cerebral vein --> great cerebral vein
157
List the 3 structures of the Brainstem.
* Midbrain * Pons * Medulla Oblongata
158
What is the most superior region of the brainstem?
Midbrain
159
What are the components of the midbrain?
Tectum: Four colliculi (x2 superior + x2 inferior) - Quadrigeminal brachium extend laterally from each colliculus - -> Superior Quadrigeminal Brachium extends between Superior colliculus and retina of eye - -> Inferior Quadrigeminal Brachium extends from lateral lemniscus and inferior colliculus to medial geniculate body Cerebral Peduncles: Extent from cerebral hemispheres converging to meet at Pons,, separated by interpeduncular fossa
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Which Cranial nerve exists between the Cerebral peduncles?
Oculomotor Nerve CN III
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What are the lateral extensions of the colliculi called?
Quadrigeminal brachium
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What does the Superior Quadrigeminal brachium connect?
Superior colliculus and retina of eye
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What does the Inferior Quadrigeminal brachium connect?
Inferior colliculus and lateral lemniscus to medial geniculate body
164
Which Cranial Nerve sweeps across the anterior surface of the Midbrain?
Trochlear Nerve CN IV
165
Outline the internal anatomy of the Midbrain at the level of the Inferior Colliculus.
* Frontopontine fibres: Medially * Corticospinal fibres: Motor fibres from primary motor cortex * Corticobulbar tracts: Motor fibres from primary motor cortex * Temporopontine fibres: Posterolaterally • Substantia nigra (posterior), separating two regions of cerebral peduncles. Two regions of SN --> SNr (anterior) + SNc (posterior) * Tegmentum: located posterior to substantia nigra, continuous with that found in the pons; continuous at midline * Cerebral aqueduct: Midline structure surrounded by periaqueductal gray matter (central gray matter). Within periaqueductal gray matter is within mesencephalic nucleus of CN 5 (trigeminal nerve) and trochlear nucleus with fibres continuing around gray matter to exit midbrain. * Superior cerebellar peduncles decussation seen centrally at level with reticular formation lateral * Tectum at posterior pole, containing inferior colliculus
166
List 4 Structures present internally at the Inferior Colliculus of the Midbrain.
- Frontopontine fibres - Corticospinal fibres - Corticobulbar fibres - Temporopontine fibres - Substantia nigra - Tegmentum - Cerebral aqueduct - Superior cerebellar peduncles - Tectum
167
List 3 structures resent at the level of the superior colliculus of the Midbrain.
- Oculomotor nucleus and oculomotor nerve - Superior colliculi - Red nuclei: decussation of rubrospinal tract anterior and reticular formation
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What is the Pons?
Group of nerves connecting cerebrum and cerebellum acting as a 'bridge'
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Outline the anterior surface of the external anatomy of the Pons.
- Basilar groove - Pontomedullary junction - CN V (lateral, mid-Pons) - CN VI (Pontomedullary junction) - CN VII (Cerebellopontine angle) - CN VIII (Lateral to CN VII)
170
Outline the posterior surface of the external anatomy of the Pons.
- Medial eminence - Facial colliculus - Stria medullaris - Cerebellopontine angle
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Outline the internal anatomy of the Pons
1) Ventral Pons • Pontine nuclei: coordinating 2) Tegmentum (evolutionarily older, forming reticular formation --> arousal and attentiveness) • Reticular formation
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List the Cranial Nerves originating in the Pons
CN V, CN VI, CN VII, CN VIII
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What process can you use to approach the diagnosis of a lesion?
1) Location of lesion • Localised symptoms or signs • Functional anatomy, including blood supply 2) Type of Lesion • Speed of onset • Natural history of lesion (disease process): Progressive, regressive, remitting-relapsing • Systems affected: Restricted to Nervous System vs Systemic 3) Treatment
174
List the Ascending pathways.
A) Dorsal Column-Medial Lemniscal Pathway (DCML) B) Anterolateral System (AST + LST) C) Spinocerebellar Tracts (Unconscious Sensation)
175
Outline the path of sensory information along the DCML.
Fine touch/Vibration/Proprioception ≈ sensory receptor --> Sensory neurones - Upper limb (T6 and above) @ Fasciculus cuneatus (lateral part of dorsal column) synapsing at Nucleus Cuneatus of MO - Lower limb (T6 and below): Fasciculus Gracilis (medial part of dorsal column) synapsing at Nucleus gracilis 2 order neurones begin and decussate in MO to contralateral side of medial lemniscus of thalamus 3rd order neurones transmit to ipsilateral primary sensory cortex of brain (homunculus)
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Where would a fine touch sensation travel specifically from the Upper Limb?
T6 so travels in Fasciculus Cuneatus
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Where would a fine touch sensation travel specifically from the Lower Limb?
T6 or below so travels in Fasciculus Gracilis
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What sensations does the DCML transmit.
Fine touch/vibration/ Proprioception
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Where do secondary neurones of the DCML decussate?
MO, travelling to contralateral medial lemniscus of thalamus
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What is the most dominant tract of the spinothalamic pathway? What does it transmit?
Lateral Spinothalamic Tract Pain and Temperature
181
Outline the route of transmitting pain or temperature in the body.
Sensory receptors detect pain or temperature and transmit impulse along sensory neurones which synapse at dorsal horn (substantia gelatinosa), 1-2 vertebral levels above which they were transmitted. Secondary neurones ascends to the thalamus Third order neurones travel from thalamus to the ipsilateral primary cortex of the brain
182
Which pathway transmits unconscious proprioception?
Spinocerebellar pathway
183
List the four individual pathways of the Spinocerebellar tracts and what they transmit and where.
* Anterior spinocerebellar tract: Proprioceptive information from lower limbs; decussate twice thus terminate in ipsilateral cerebellum * Posterior spinocerebellar tract: Proprioceptive information from lower limbs to ipsilateral cerebellum * Rostral spinocerebellar tract: Proprioceptive information from upper limbs to ipsilateral cerebellum * Cuneocerebellar tract: Proprioceptive information from upper limbs to ipsilateral cerebellum
184
List the two types of descending tracts involved in movement function.
1) Pyramidal tracts: Originate in cerebral cortex; carry motor fibres to spinal cord and brainstem; voluntary control of musculature 2) Extrapyramidal tracts: Originate in brainstem; motor fibres to spinal cord; involuntary and automatic control of musculature (balance, tone, posture and locomotion)
185
Which descending pathway is involved in voluntary control of musculature?
Pyramidal tracts: Originate in cerebral cortex; carry motor fibres to spinal cord and brainstem; voluntary control of musculature
186
Which descending pathway is involved in involuntary control and automatic control of musculature?
Extrapyramidal tracts: Originate in brainstem; motor fibres to spinal cord; involuntary and automatic control of musculature (balance, tone, posture and locomotion)
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What are the two divisions of the Pyramidal tracts?
* Corticospinal tract: Musculature of body | * Corticobulbar tract: Musculature of head and neck
188
Outline the pathway of the Corticospinal tract.
• Inputs: Primary motor cortex + Premotor Cortex + Supplementary motor area + Somatosensory area (regulate activity of ascending tracts) • Cell bodies in cerebral cortex which converge and descend through internal capsule (white matter pathway between thalamus and basal ganglia) --> crus cerebri of midbrain, pons and through medulla --> i) Lateral corticospinal tract (90%) decussate in medulla and descend into spinal cord, terminating into ventral horn ii) Anterior corticospinal tract (10%) remain ipsilateral and descend into spinal cord, decussating and terminating in ventral horn of cervical and upper thoracic segmental levels • Two divisions of corticospinal tract (Lateral - decussates in medulla cf Anterior - decussates in spinal cord) • Neurones terminate in ventral horn at all segmental levels
189
Outline the pathway of the Corticobulbar tract.
* Inputs: Primary motor cortex + Premotor Cortex + Supplementary motor area + Somatosensory area (regulate activity of ascending tracts) * Cell bodies from lateral aspect of primary motor cortex * Cell bodies in primary motor cortex --> converge and pass through internal capsule --> terminate on motor nuclei of cranial nerves --> synapse with LMNs carrying motor signals to muscles of face and neck
190
What are the 4 extrapyramidal tracts?
Vestibulospinal (no decussate = ipsilateral), Reticulospinal (no decussate = ipsilateral) , Rubrospinal (decussate = contralateral) Tectospinal (decussate = contralateral)
191
Which of the extrapyramidal tracts do not decussate?
Vestibulospinal (no decussate = ipsilateral) Reticulospinal (no decussate = ipsilateral)
192
Which of the extrapyramidal tracts do decussate?
Rubrospinal (decussate = contralateral) Tectospinal (decussate = contralateral)
193
List the main signs of an UMN lesion.
* No wasting/fasciculation * Spastic/paralysis * Spasticity (tone) * Hyperreflexia * Clonus (sustained, rhythmic contractions) * Positive Babinski’s sign
194
List the main signs of a LMN lesion.
* Fasciculation * May be pronator drift * Hypotonia * Hyporeflexia * Negative Babinski’s sign
195
List 3 common types of lesion by categories and examples of each
1) Degenerative • Slow • Months – years • E.g. PD, Alzheimer’s 2) Infectious • Acute (hours) – Subacute (days) • Systemic inflammatory features present e.g. Fever ``` 3) Vascular • Older • Male • Sudden onset (minutes) • Vascular risk factors present ``` ``` 4) Autoimmune • Young • Female • Relapsing-Remitting course • E.g. Multiple Sclerosis, Vasculitis ``` 5) Tumour • Slow and gradual • Weeks – years • Primary or metastasis
196
Outline the common rules of the Brainstem Nuclei.
* Motor is Medial – 4 structures in the midline * 4 Cranial Nerves in the Midbrain, 4 in the Medulla, 4 in the PONS * 4 motor nuclei in the midline (CN 3, CN 4, CN 6 and CN 12) are factors of 12 (except 1 and 2) * Remaining cranial nerve nuclei are on the Side
197
Outline the Process of Eye movements regarding the CN VI and CN III
• Horizontal gave centre input to abducens (CN 6) nucleus to direct gaze to ipsilateral side (LHS) --> One subset of neurons projects directly to ipsilateral lateral rectus via CN 6 + Subset of neurons in abducens nucleus crosses midline and travels in MLF to contralateral oculomotor nucleus --> oculomotor neurons innervate ipsilateral medial rectus and eye moves to contralateral side --? both eyes more in the same direction (left)
198
1) Scenario 1: 62 year old patient wakes with severe chest pain, radiating to back, doesn't go to doctor. Next day difficulty with micturition, pain below umbilicus, unable to feel hot water in legs. Spinothalamic sensory level at T10, normal tone and power. Where is the Lesion?
ANS: Spinothalamic tract as pain (+ temperature) runs in lateral spinothalamic tract which decussates early on (1-2 vertebral levels above). Location: T9 (artery of Adamkiewicz --> anterior spinal artery)) Spares dorsal columns if anterior spinal cord affected (e.g. from aortic dissection). Anterior spinal cord syndrome bilaterally
199
2) Scenario 2: 54 year old nurse, pain down whole of right arm and neck. O/E no atrophy, normal power, absent biceps and supinator reflexes but brisk triceps. Where is the lesion?
Corticospinal tract as somatic motor (body cf head and neck) thus not corticobulbar. Location: C5, C6 (absent biceps and supinator reflexes) partial C7 ? (brisk triceps - hyperreflexia) Lower Motor Neurone Lesion of Biceps (absent biceps) cf Upper motor neurone lesion (triceps hyper-reflexia) Disc spondylolisthesis at C5, C6 hitting nerve roots and pressing on spinal cord causing lower motor neurone lesion at the level or above and upper motor neurone lesion below the level of injury - brisk, exaggerated C7 (reduced inhibition of triceps)
200
3) Scenario 3: 48 year old, obese, developed patch of numbness over left thigh, increased in size over a week, some pain around groin. O/E oval patch of sensory loss 20cm x 10cm Where is the lesion?
Dorsal column medial lemniscus pathway at level (sensory loss) Spinothalamic tract (pain around groin) L2/L3 region affected (lateral cutaneous nerve of the thigh) however spinothalamic tract crosses early on (lesion is contralateral if on left) Meralgia paresthetica
201
4) Scenario 4: 45 year old male presents with sudden onset of dysarthria. O/E left hemiplegia, deviation of tongue to right and loss of JPS to upper and lower left limbs. Where is the lesion?
Lesion is medial: 1) right corticospinal tract (motor) so UMN signs in left upper and lower limbs Right medial lemniscus so loss of JPS, fin touch and vibration sense from left side of body (decussates in medulla) Lesion is in the medulla: Right hypoglossal nucleus thus right side tongue weakness (dysarthria). May observe atrophy and fasciculation as LMN signs) Sudden onset: Anterior spinal artery stroke likely. Medial medullary syndrome Medial medullary syndrome - right side of medulla affected.
202
5) Scenario 5: 40 year old woman undergoing physical exam at her GP. O/E impaired adduction in left eye when asked to look to the right. Apparent nystagmus in right abducting eye. Found to have impaired adduction of right eye when asked to look left. There is also an apparent nystagmus in the left abducting eye. On further questioning, she tells her GP she had an episode of pain behind her right eye with partial loss of colour vision which lasted 1 month in her 30s. Where is the lesion?
Lesion is medial: 1) Eyeball movements affected by Median Longitudinal Fasciculus causing poor eye movement to the right when asked. Left eye impaired thus medial rectus (lesion affecting Abducens nucleus or Oculomotor nucleus) Lesion is in the midbrain/medulla Inter-nuclear ophthalmoplegia (demyelination conditions e.g. Multiple Sclerosis)
203
6) Scenario 6: A 60 year old male presents with sudden onset dysphagia and difficulty walking. He noticed his right eyelid had suddenly dropped. When he entered the room his gait seemed ataxic. On examination he has partial ptosis and meiosis of right eye, with loss of pain and temperature sensation on the same side of the face. In his left lower limbs he has lost sense of pain and temperature, however joint position sense remains intact. His palate has deviated to the left. Where is the lesion?
Lesion is lateral: 1) Spinothalamic Tract: Loss of pain and temperature, crude touch from left upper and lower limbs and face 2) Spinocerebellar Tract: Limb ataxia on right side 3) Sympathetic pathway: Right Horner's Syndrome 4) Trigeminal nucleus: Loss of pain and temperature from right side of face Lesion likely to be at level of medulla: - Nucleus ambiguus: Dysphagia, ipsilateral loss of gag reflex and palate will pull up to left side - Ipsilateral SCM ± trapezius weakness
204
7) Scenario 7: A 35 year old female presents with tinnitus and gradual loss of hearing in the right ear. The patient mentions she has also been having symptoms of vertigo over the past few weeks with occasional vomiting, in addition to slight weakness on the right side of her face. On examination she is found to have mild nystagmus, a right-sided facial paraesthesia and loss of corneal reflex.
Lesion is lateral and at level of the pons: Tinnitus and sensorineural hearing loss in the right ear and vertigo so right vestibulocochlear nerve/nucleus Right facial weakness and paraesthesia so facial nerve/nuclei and trigeminal nerve/nuclei on the right. Loss of corneal reflex is an early sign along with weakness of muscles of mastications. Acoustic neuroma/vestibular schwannoma (benign tumour) growing gradually in the cerebellar-pontine angle cistern
205
Outline the process by which static tilt is detected, aiding balance. Where does this occur?
• Movement -> Otolith membrane (otolith with gelatinous structure) moves -> Sterocilia + Kinocilium detect directional movement via K+/Ca2+-ion channels opening -> relayed to nerve fibres of vestibular nerve innervating either saccule macule or utricle macule ≈ static tilt and linear translation Saccule and Utricle
206
Outline the process by which rotational acceleration is detected and where this is done.
• Movement -> Endolymph movement across cupula -> moves kinocilium + stereocilia ≈ open channels ≈ movement to be perceived Semi-circular canals
207
Outline the process of the Caloric Test in Brainstem testing in Comatose patients and those with Brainstem death. What would you anticipate for each?
1) Warm water in external meatus of patient (e.g. RHS) ≈ endolymph rises -> increased firing ≈ nystagmus pattern of irrigated ear is slow away and fast in direction of rotation 2) Cold water in external meatus of patient (e.g. RHS) ≈ endolymph decreases -> reduced firing ≈ nystagmus pattern of irrigated ear is fast away and slow towards Mnemonic: COWS – Cold Opposite, Warm Same - > Find: In comatose patients, no fast saccade, only slow component - > Find: Brainstem death: No vestibulo-ocular reflexes * Quick movement related to cerebrum (cortex) * Slow movement related brainstem
208
State the three cerebellar pathways.
* Spinocerebellar: Simple movements * Cerebrocerebellar: Complex movements * Vestibulocerebellar: Posture and balance
209
What are the two inhibitory neurones types of the Cerebellum.
* Purkinje cells and Purkinje axon --> immune response can occur against Purkinje axons * Basket cell axon
210
What are the two Excitatory neurones types of the Cerebellum.
* Climbing fibres (inputs from olivary nucleus): old inputs produce climbing fibres * Mossy fibres (inputs from pontine nuclei and other sources)
211
What are the 3 lobes of the cerebellum and which pathways run in each?
Pathways: • Spinocerebellar: Simple movements • Cerebrocerebellar: Complex movements • Vestibulocerebellar: Posture and balance Structure: 3 lobes • Anterior lobe • Posterior lobe • Flocculonodular lobe
212
List the nuclei of the cerebellum.
Don’t Eat Greasy Food Lateral --> Medial: Dentate, Emboliform, Globose, Fastigial Nucleus 1) Dentate Nucleus 2) Emboliform nucleus 3) Globose nucleus 4) Fastigial nucleus