Block 5 - Musculoskeletal and Nervous System 1 Flashcards
1
Q
What are the 3 phases of the stance phase?
How much of the gait cycle does it make up?
A
heel-strike (heel hits ground)
Mid-stance (full foot on ground)
Propulsion (only toe is remaining)
60%
2
Q
What are the 3 stages of the swing phase?
How much of the gait cycle does it make up?
A
Toe off, limb swing, heel strike
40%
3
Q
What is the difference between stride and step?
A
Stride: Length between one foot and the same foot hitting the ground
Step: Length between one foot and the opposite foot hitting the ground
4
Q
What is the ratio of tendon to muscle and what does this help with?
A
Tendons are long compared to muscles
Help with running
5
Q
What do muscles attach?
A
Stable bones to moveable bones
6
Q
Define TORQUE
A
The rotional force when skeletal muscles contract bones around a joint
7
Q
What are the 4 types of muscles?
A
Agonists and Antagonists: Opposing movement
Synergist: 2 different positions but both muscles are agonists
Concentric: Muscle shortens and pulls the bone via the tendon
Eccentric: Muscle length increases (e.g. kicking)
8
Q
What is the muscle lever arm?
What does the distance of it determine?
What is increased if the distance is longer?
What is increased if the distance is shorter?
A
Perpendicular distance from the line of muscle action to the joint
The distance determines the muscle’s ability to transfer force
Longer = increased power
Shorter = increased speed
9
Q
What does balance involve?
A
Coordinating muscle systems
10
Q
What is the role of the cerebellum?
A
To adjust movement based on sensory and proprioceptive input
11
Q
What is the size of the downward force a product of?
A
Mass and gravity
12
Q
Where is the centre of mass in a human?
A
Pelvis
Mid-anterior to the second sarcal vertebrae
13
Q
What are the main muscles that work during the stance phase?
A
Heel strike: Dorsiflexion in the ankle, hip extensors lower the foot and intrinsic muscles preserve the arch to transfer weight
Mid-stance and Propulsion : Hip abductors stabilise the pelvis, knee extensors stabilise the knee and intrinsic foot muscles increase stability
14
Q
What are the main muscles that work during the swing phase?
A
Toe off: Eccentric contraction of the hip, big toe flexes increasing stability
Initial swing: Ankle dorsiflexors clear the foot and move the leg
Terminal swing: Hip extensors and knee flexors decelerate the leg, ankle dorsiflexors position the foot and knee extensors straighten the leg
15
Q
How do heels and flip-flops affect the gait cycle?
A
Heels: Shortened Achilles tendon and calf muscles
Flip-Flops: Shorter steps and stride length
16
Q
What happens to your muscles as you get older?
A
Decreased muscle bulk and flexibility
17
Q
What happens during Antalgic Gait?
Example
A
Decreased use of the affected limb causes a decreased stance and swing phase and an increased step length
e.g. stone in your shoe
18
Q
What happens during Ataxic Gait?
What is another name for it?
Example
A
Decreased cerebellar activity causes uncoordinated movement with a wide base and double tap of the heel
Cerebellar gait
Multiple Sclerosis
19
Q
What happens during Parkinsonian Gait?
A
Short, accelerating steps on tiptoes
Trunk and legs flexed stiffly at the hips and knees
20
Q
What happens during Myopathic Gait?
What is another name for it?
Example
A
Weak pelvic muscles cause decreased stability and the pelvis tilts to the non-weight bearing leg
Waddling gait
Muscular diseases
21
Q
What happens during Neuropathic Gait?
What is another name for it?
Example
A
Weak dorsiflexors lead to increased stepping to avoid toe dragging
High-Stepping Gait
Peripheral nerve disease
22
Q
What happens during Trendelenberg Gait?
A
Dislocation/hip paralysis stops the hip abductors from working.
The pelvis drops as the good limb enters swing phase so the lumbar spine flexes towards the paralysed side to bring the centre of gravity onto the damaged limb
23
Q
What happens during ‘Footballer’s Favourite’?
A
Deceleration on an extended knee tears the ANTERIOR CRUCIATE ligament
24
Q
What happens during Coxa VERA?
What type of gait does it cause?
A
Decreased angle of the femoral neck leads to shortening of the abductors and lower limb
‘Duck waddle gait’
25
What happens during Coxa VALGA?
| Example
Increased angle of the femoral neck by abductor weakness and decrease in normal weight bearing
Cerebral Palsy
26
What happens during pes planus?
The arch in the foot collapses leading to increased weight bearing
27
Two ways in which the pelvis adapted for bipedalism?
The pelvis is more wide than high which brings the sarcoiliac joint closer to the hip joint to decrease weight from the vertebrae
The iliac bone is curved to make the hip muscles abuctors
28
How is the 'locking mechanism' of the knee established?
When the quadricep muscles contract, the femur rotates which compacts the joint
The anterior cruciate and collateral ligaments are elongated and tensed
29
What does the bi-condyle angle of the femur do?
| What else increases support of the leg?
Ensure that the weight is shifted inferior to the trunk and the centre of mass is moved to the midline
The femur head is also a lot larger
30
What stops the trunk from rotating backwards at the hip joint?
How is weight and centre of mass balanced over the lower limbs
Tension in the inferomordial ligament
| The cervical and lumbar curves of the vertebrae cancel out
31
What adaptation for bipedalism do the feet have?
| What three things does this do?
A 2 part longitudinal arch (medial and lateral)
| Distribute and transfer weight, act as a shock absorber
32
What three signals does the skeleton receive for development?
Genetic, functional and loading (environmental) signals
33
What forms the skull, spinal cord and body
| Three separate things!
Skull: Neural crest
Spinal cord: Neural folds
Body: Mesoderm
34
What parts of the body are formed in cartilage and what parts are formed in neural membrane?
Cartilage: Body, cranial base and nasal septum
| Neural membrane: Spinal cord
35
What does the vertebrae develop from?
Somites
36
Where do the limb buds grow from?
Apical external ridge
37
What genes code for the bones?
HOX Genes
38
What kind of growth does cartilage carry out?
Interstitial growth
39
Where is bone produced first?
Central shaft and ends
40
What is found in the epiphyseal growth plate?
Ossification sensors
41
What is hyaline cartilage made from?
Chondrocyte cells
| Intercellular matrix made from fibres and a ground substance containing electrolytes and proteins
42
What is cartilage laid down by?
Chondroblasts
43
How does cartilage grow?
Cartilage cells expand which give rise to new flat cells underneath which then also expand
44
How can you tell there is NOT a fracture?
An unbroken light line around the bone
45
What are the four parts of the bone?
Ephiphysis --> Physis --> Metaphysis --> Diaphysis
46
What is another word for spongy bone?
Cancellous
47
What is the dense outer cortex made from?
| What system does it make?
A series of layers (lamellae) which surround blood vessels
| A tubular system called an Osteon/Haversian system
48
What surrounds the lamellae?
Collagen fibres, cells, minerals
| Osteocytes are found between the lamellae in holes called lacunae
49
What is special about the ground structure of bone?
It is mineralised
50
What 2 things does trabecula resist?
Compression and bending
51
What makes up the central part of bone?
Marrow
52
3 causes of osteoporosis?
Under-loaded bone
Under-maintained bone
Too much bone is removed
53
What are the stages of repairing a fracture?
| What two words describe the process of repairing a fracture?
Haematoma: Clotting after the break
Proliferation: Mineralising cartilage formed
Callus: Woven bone produced
Cosolidation: New bone made by osteoblasts
Remodelling
A continuous healing process
54
What are the 3 main types of joints?
```
Fibrous joints (Synarthroses) e.g. long bone and sutures
Cartinaginous joints (Ampiarthrosis) e.g. ribs, sternum, epiphyseal plate
Synovial joints (Diarthroses) e.g. knee
```
55
What is a synovial joint made from?
2 long bones with hyaline cartilage in a joint capsule lined with synovial membrane (connective tissue) which secretes fluid for lubrication
The surface is made from flattened cells which become more rounded as you reach the bone
56
What causes osteoarthritis?
Tearing of the surface layer of cartilage means forces are distributed differently and there is more bone on bone interaction
57
Define 'the nervous system'
| What is it made from?
The system of cells, tissues and organs that regulate responses to internal and external stimuli
Made from interconnected neurones
58
Which division of the autonomic nervous system creates memories?
Sensory
59
What is found between the cell body and axon?
Axon hillock
60
What are the 4 types of neurones?
Unipolar: Cell body one end and terminal branches the other
Multipolar: Same as unipolar but with many dendrites off the cell body
Bipolar: Cell body in the middle; terminal branches one end and receptor at the other
Pseudounipolar: Cell body off a branch in the middle; terminal branches one end and receptor at the other
61
What is grey and white matter?
| Where is it found in the brain, spinal cord and brainstem?
Grey: Contains cell bodies
White: Contains axons
BRAIN: Grey outside, white inside
SPINAL CORD: Grey inside, white outside
BRAINSTEM: No distinction
62
What are ganglia?
| What do you call ganglia found in the brain?
Bundles of axons which contain cell bodies
| Basogalglia
63
What is grey and white matter made up from in the CNS?
Grey: Cortex and nuclei
White: Tracts
64
What does dorsal and ventral mean in the brain?
Ventral: Inferior
Dorsal: Superior
65
What are the 5 layers of a nerve?
Nerve --> Epineurium --> Perineurium --> Fascicle --> Endoneurium
66
What is Aphasia?
Can't grasp sensory information
67
What is Hemianopia?
Loss of vision in one eye
68
State the progression of nerves from the spinal cord
Dorsal and ventral rootlets --> spinal nerve (in intervertebral foramen) --> dorsal and ventral rami --> plexuses
69
What property can the nerves in plexuses have distal to the spinal cord?
Sensory and motor functions
70
What do the dorsal rami supply?
A small area on the back either side of the vertebral column
71
What is a dermatome and myotome supplied by?
A single spinal SEGMENT
72
What is heiplegia?
Half body paralysis
73
What is neglect?
Forget one half of the body
74
What is the somite?
Specialised areas of mesoderm found either side of the neural tube (musculoskeletal structures)
75
What is the notocord?
A tube of tissue found beneath the neural tube which is a precursor to the vertebral column
76
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Where do neural crest cells come from?
Where do they migrate?
What do they form?
What do they form in the cranium?
What do they form in the trunk?
```
Cells from the neural folds which migrate to the endoderm forming the 4th germ layer
CRANIUM: Bone, cartilage, connective tissue and ganglia
Migrate to the pharyngeal arches (each contain bone muscle, blood supply and cranial nerve)
TRUNK: Endocrine connective tissue, glia, pigment cells and sensory nerves
77
What does the neural tube split into near the brain?
Forebrain: Splits into Diencephalon (thalamus and ganglia) and Telencephalon (cerebral hemispheres)
Midbrain: Brainstem
Hindbrain: Brainstem
78
Where is the thalamus found?
Inside the basal ganglia
79
What are the three parts of the caudate nucleus?
| Where is it found?
Head, body and tail
| Runs in a semi-circle around the outside of the basal ganglia along the edge of the lateral ventricle
80
What is the fornix and hippocampus involved in?
| What shape is it and where does it run?
Memory
| C-shaped semi-circle which runs in the margin of the lateral ventricle
81
What is the embryonic precursor for the:
Posterior horn
Anterior horn
White matter
Posterior horn: Alar plates
Anterior horn: Basal plates
White matter: Roof and floor plate
82
Are anterior or posterior horns motor or sensory?
| Where do the nerves grow from for each of these regions?
Anterior: MOTOR --> nerves grow out from cell bodies in the spinal cord
Posterior: SENSORY --> nerves grow into the spinal cord from neural crest cells
83
Which cranial nerves are:
Extensions of the brain
Pure motor nerves
Mixed nerves - what do these supply
Extensions of the brain: Olfactory and Optic
Pure motor nerves: Oculomotor, Trochlear, Abducens and Hypoglossal
Mixed nerves - Pharangeal arches (1: Trigeminal, 2:Facial, 3: Glossopharyngeal, 4: Vagus)
84
What percentage of the bone is organic and what percentage is inorganic?
What are the main components of the organic and inorganic part?
Organic: 40% --> Type 1 collagen and non-collagenous proteins
Inorganic: 60% --> Minerals
85
Where does bone remodelling occur?
In resorption pits between the matrix and marrow in trabeculae bone
86
What is the role of an osteoblast?
Lay down bone and form the matrix (type 1 collagen)
| Vesicles enter the matrix for mineralisation
87
What is the role of an osteocyte?
Maintain bone by burying into it and extending cytoplasmic extensions that detect chemical changes
88
What is the role of an osteoclast?
| What is its structure?
Binds to the matrix by adhesion molecules
Destroys bone by HCl (inorganic) and phagocytosis (organic)
MULTI-nucleated macrophage
89
What is the cycle of bone remodelling?
```
Quiescence: No activity
Resorption: Osteoclast activity
Reversal: Stem cells --> osteoblasts
Formation: New bone
Mineralisation: Mineralised bone
```
90
How much Calcium is in the body?
What percentage is found in the skeleton?
How is it transported in the blood?
1000g
99% in skeleton and 1% elsewhere
Ionised, Protein bound (albumin) or Complexed (to citrate or phosphate)
91
How much Phosphorus is in the body?
What percentage is found in the skeleton?
How is it transported in the blood?
How are the levels regulated?
600g
85% in skeleton and 15% elsewhere
Ionised, Protein bound or Complexed (Na, Ca, Mg)
Regulated by PTH
92
How is Vitamin D synthesised?
| How can it be absorbed straight into the body?
In the skin from 7-dehydrocholesterol by UV light
| Injestion
93
How is Vitamin D activated?
Hydroxylation (adding OH) by the enzyme 25-hydroxylase
Liver: D3 + OH --> 25(OH)D3
Kidney: 25(OH)D3 + OH --> 1,25(OH)D3
94
What increases and decreases the levels of activate D3?
| What does the active form of D3 do?
Increases: PTH
Decreases: Ca and P
Active: Increase Ca and P absorption from the intestine and increases osteoclast activity
95
What is the negative feedback mechanism used to prevent Vitamin D toxicity?
In the kidney:
| 25(OH)D3 + OH --> 24,25(OH)D3
96
When and where is the Parathyroid Hormone secreted?
What is its role?
How does it do this? (5)
Secreted by the parathyroid gland when Ca levels decrease. It's role is to increase them by:
Increasing osteoclasts, decreasing osteoblasts, decreasing excretion, increasing absorption and increasing Vitamin D
97
What is PTHrP?
| What is it produced for?
Parathyroid Hormone Related Protein
| Local bone development
98
When and where is Calcitonin produced?
What is its role?
How does it do this?
Secreted by Parafollicular cells in the thyroid when Ca levels increase. Its role is to decrease them by:
Decreasing osteclasts, increasing osteoblasts and decreasing Vitamin D
99
What are the two sex hormones involved in bone remodelling?
| What do they both do and how?
Oestrogen and Androgen
| Decrease osteoclasts and increase osteoblasts to maintain bone mass and density
100
What are 5 causes of hypercalcaemia?
Primary hyperparathyroidism, Hyperthyroidism, Increased Vitamin D, Malignancy, Immobilisation
101
What is the cause of Primary Hyperparathyroidism?
| What are 5 symptoms?
Increased secretion of PTH by a tumour
```
Osteitis Fibrosa (Increased bone loss leads to replacement of bone with fibrous tissue)
Deformity (in extremities), erosion, fracture, pain,
```
102
What are 3 causes of hypocalcaemia?
Renal failure, decrease in Vitamin D and an immature thyroid
103
What is another word for rickets?
What actually is it?
What are 6 causes?
What are 3 symptoms?
Osteomalacia
Increase in non-mineralised bone
CAUSES: Anticonvulsants, Decreased sunlight, Hydroxylase deficiency, Malabsorption, Renal disease, Vitamin D deficiency/resistance,
SYMPTOMS: Pain, weakness, bowing in long bones
104
5 drugs used to treat Osteoporosis
```
Calcium supplements
Hormone replacement
Bisphosphates
Calcitonin
Oestrogen Receptor Modulators
```
105
Where does the spinal column run from?
| How long is it?
From the foramen magnum to L1/L2
| 42-45cm
106
What are the 5 sections of the spinal cord?
Cervical, Thoracic, Lumbar, Sarcal and Coccygeal
107
What order do the meningeal coverings go in?
(CNS) Pia, Arachnoid, Dura (OUTSIDE)
108
What is the difference between the space in the skull vs the space in the spinal cord?
What are the 2 spaces called?
Skull: A potential space called the Extradural space
| Spinal cord: An actual space called the Subarachnoid space
109
Define spinal segment
Bit of spinal cord bounded by the rootlets of a single spinal nerve
110
What part of the spinal cord is sensory and what part is motor?
VENTRAL: Motor
DORSAL: Sensory
111
What is the dorsal root ganglion made from?
Cell bodies
112
What vertebral level does the spinal cord end at?
| What is it called?
L1/L2
| Condus Medullaris
113
What is the cistern?
| What is the clinical significance of it?
A subarachnoid space with no spinal cord but spinal fluid
| Lumbar Puncture
114
What is funiculi?
White matter divided into columns (tracts)
115
Define commissure
Fibres which cross the midline
116
Where do 1st order neurons run from and to?
What type of neuron are they?
Where are the cell bodies found?
Receptor --> dorsal route of spinal nerves
Pseudounipolar
Cell bodies i dorsal root ganglion
117
Where do 2nd order neurons run from and to?
| What do they do?
Spinal cord --> Thalamus
| They decussate
118
Where do 3rd order neurons run from and to?
Thalamus --> Cerebral cortex
119
What is the internal capsule?
A white matter tract near the thalamus that fibres pass through
120
What is the medial lemniscus?
A bundle of tracts which cross the midline
121
What is the fasciculus graclis and fasciculus cuneatus?
| Where do they synapse?
Fasciculus Graclis: Medial fibre which supply's the lower body
Fasciculus Cuneatus: Medial fibre which supply's the upper body
SYNAPSE: Cuneate/Gracilus nucleus
122
What type of neurone is in the DCMLP?
| What is this pathway involved in?
1st order
| 2 point discrimination, pressure, vibration and proprioception
123
Where does the neurone decussate in the spinothalamic tract?
What type of neurone is it?
What does it form at the brainstem?
```
Dorsolateral fassiculus (of Lissauer)
2nd order
Brainstem = forms the spinal lemniscus
```
124
What is the anterior spinothalamic path involved in?
| What is the lateral spinothalamic path involved in?
Anterior: Crude and localised touch
Lateral: Pain and temperature
125
What are secondary collateral neurones?
Neurones which project information to other parts of the brain
126
What are the 2 conscious perception tracts?
DCLM
| Spinothalamic
127
What are the 4 unconscious perception tracts?
Spino-cerebellar
Spino-olivary
Spino-tectal
Spino-reticular
128
Where does the spinocerelellar tract run from and to?
| What type of information does it pick up?
Spinal cord --> Cerebellum (ipsilaterally)
| Internal information
129
Where does the spino-olivary tract run to?
| What is it involved in?
Runs to the accessory olivary nuclei and cerebellum
| Co-ordination and balance
130
Where does the spino-tectal tract run to?
| What is it involved in?
Runs to the superior colliculi in the tectum
| Reflex turning of the head to cuneatus stimuli
131
Where does the spino-reticular tract run to?
| What is it involved in?
Runs to the reticular activating system
| Arousing conciousness through cuneatus stimulation
132
What is somatotropic arrangement?
The organisation of axons in tracts
Medial = lower
Lateral = higher
133
What happens in Brown Sequard Syndrome?
| Ipsilateral and contralateal symptoms
Lesion in one half of the spinal cord
Ipsilateral: Paralysis and loss of proprioception
Contralateral: Loss of pain and temperature
134
Define action potential
| How long does it take to reach the end of the neurone?
A rapid change in electrical potential across the plasma membrane of the cell
A few milliseconds
135
Three things which can generate action potentials?
Neurones, muscles and hormones
136
Where do signals arrive at an axon?
Dendrites
137
What type of response is there at the axon hillock?
An all or nothing response
| The threshold must be reached
138
Define membrane potential
The difference in electrical potential between the interior and exterior of a cell caused by a separation of electrical charge
139
How is a resting potential established?
By an electrochemical gradient
140
When do ligand gated ion channels open?
In response to a drug
141
How does the sodium potassium pump work?
3 Na OUT
| 2 K IN
142
When is equilibrium reached in a neurone?
When there is an electrochemical balance between electrical and chemical forces
143
What is the equilibrium potential?
What does it depend on?
What is it predicted by?
Equilibrium Potential: The voltage when an ion's net flow across a membrane is zero
Depends on: Charge and concentration gradient
Predicted by: NERNST EQUATION
144
What is the equilirbium potential of potassium and sodium as worked out by the Nernst equation?
Potassium: -80mV
Sodium: +60mV
145
What is a positive equilibrium potential caused by?
Increased potassium on the outside
146
What is the threshold during an action potential?
-55mV
147
What is the relative refractory peroid?
An action potential can still be made but only if there is a very large stimulus
148
Define subthreshold
Magnitude of a graded response (below 55mV)
149
Define suprathreshold
Frequency of action potentials (more than 55mV)
150
What is the Goldmann equation?
| What value does it give in a neurone?
Resting membrane potential = 61log (permeability of each ion out/permeability of each ion in added together)
= -70mV
151
What does sodium cause at the axon hillock?
Local depolarisation
152
What attacks the myelin sheath in MS?
Where?
What are 3 symptoms in the axons?
T cells
Brain, spinal cord and optic nerve
Inflammation, lesions and scarring
153
Define pain
A unpleasant sensory and emotional experience associated with actual/potential tissue damage.
It is subjective
154
Define nociception
| What can you sometimes feel pain without?
The neural process of detecting, encoding and processing unpleasant stimuli
Physiological
You can feel pain without tissue damage
155
What 2 things does pain stop during sleep?
Stops the formation of bed-sores
| Stops skeletal strain
156
What are the two types of somatic pain
Superficial and deep
157
Characteristics of superficial, deep and visceral pain?
Superficial: Sharp, brief, localised, on the skin
Deep: In between the two
Visceral: Dull, aching, burning, poorly localised, internal
158
3 examples of chronic pain
| 4 examples of acute pain
Chronic pain: Inflammation, headache, musculoskeletal
| Acute pain: Burns, cuts, muscle/ligament damage
159
Where are nociceptive sensors found?
In internal and external body tissues
160
5 examples of nociceptors
```
Thermal
Mechanical: Pressure
Chemical: e.g. spicy food
Polymodal: Most pain receptors
Sleeping: Inflammation
```
161
What are the two divisions of afferent fibres?
What types of receptors are in each division?
What are the fibres in each division called?
Rapid conduction: Low threshold mechanoreceptors (Alpha A and Alpha B)
Slow conduction: Thermo and nociceptors (Alpha D and C)
162
What are the fibres and receptors for 1st and 2nd pain?
1st: Thermal and mechanical (Ad)
2nd: Polymodal (C)
163
What are transient receptor potentials
Proteins on a neurone that open in repsonse to certain stimuli
164
What do pain neurones synapse with in the spinal cord
2nd order neurones in the lamina of the dorsal horn
165
How does congential analgesia occur?
| What can they feel?
Mutations in genes which code for nociceptor sodium ion channels
Sensory receptors
166
What happens in dissociated sensory loss?
Diminished sensory stimuli on one side and diminished pain on the other
167
How is the spinothalamic pathway involved in pain?
Thalamus --> medulla = Perception
Somatosensory cortex = localisation
Limbic system = emotion
168
How do small diameter afferents get to the brainstem?
How do they cross the medulla?
What tract do they use to enter the thalamus and cortex?
They descend in the spinal-trigeminal tract and go to the brainstem
They cross in the pars caudalis in the medulla
Enter the thalamus via the trigeminothalamic tract
Enter the cortex via the ventral posteromedial nucleus
169
How do impulses enter the pons from the face?
Cranial nerves 5,7,9 and 10
170
What neurones are involved in the gate theory?
How are they activated?
What does this lead to?
Localised inhibitory interneurones in the spinal cord activated by touching Ab and C fibres leads to reduced action potentials
171
What is the difference between physiological and pathological pain?
Physiological: Painful stimuli activate C fibres causing acute pain and non-painful stimuli activate Ab fibres causing no pain
Pathological: Painful stimuli activate C fibres causing Hyperalgesia and non-painful stimuli activate Ab fibres causing Allodynia
172
What fibres become more sensitive in hyperalgesia?
| How does sensitisation occur?
C fibres
| Surrounding areas can be affected too due to inflammation
173
6 symptoms of fibromalgia
| How is it diagnosed and treated?
Fatigue, headache, insomnia, irritable bowel, muscle stiffness, restless legs
Diagnosis: Identifying tender points
Treatment: Analgesics and antidepressants
174
What happens during neurosurgery to help pain?
Physically break the nociceptive pathway
175
Where do descending pathways in the brain arise from?
| What do these pathways do in regards to pain?
The periaqueductal grey matter (PAG) and raphe nuclei
| They decrease transmitter release from nociceptors by interacting with opioid receptors
176
What is the brainstem made from?
Midbrain, pons and medulla oblongata
177
What is found behind the brainstem?
Cerebral peduncles and interpenducular fossa
178
What are peduncles?
| What is found between the cerebral peduncles?
Tracts that link to the cerebellum
| Pair of superior and inferior colliculi between the peduncles
179
What are the nuclei of the cranial nerves?
Forebrain: 1 2
Midbrain: 3 4
Pons: 5 6 7 8
Medulla: 9 10 11 12
180
Where do the cranial nerve nuclei exit?
Ventral surface of the midbrain
| 4 = dorsal
181
Where are nuclei for the peripheral nerves?
Forebrain
182
Where do UMN and LMN tracts originate?
UMN: Cerebral cortex, cerebellum or brainstem
LMN: Brainstem or spinal cord
183
What do the basal ganglia, thalamus, cerebellum and pons form?
Descending pathways and feedback loops
184
Where is the basal ganglia nuclei?
| What function do they therefore have?
In the grey matter - a motor function
185
What are the 2 descending tracts called?
Dorsolateral
| Ventromedial
186
Ventromedial tracts:
```
What part of the white matter are the tracts in?
Where do they synapse?
What movements are they involved in?
Ipsilateral or contralateral?
What does injury lead to?
```
Ventral and medial aspects of white matter
Ventral and medial anterior horn cells
Flexors and extensors of the thigh, arm and trunk
Involved in posture and moving multiple joint
Bilateral movements (both sides through one neurone)
Ipsilateral
Injury = loss of posture, a slump but maintains fine motor movements
187
Dorsolateral tracts:
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What part of the white matter are the tracts in?
Where do they synapse?
What movements are they involved in?
Ipsilateral or contralateral?
What does injury lead to?
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Dorsal and lateral aspects of white matter
Dorsal and lateral anterior horn cells
Flexors and extensors below the elbow and knee
Act on single joints
Contralateral
Injury = normal posture and navigation but loss of fine motor movements
188
What are examples of ventromedial tracts?
Reticulospinal
Tectospinal
Vestibulospinal
189
What are examples of dorsolateral tracts?
Ruberospinal
| Corticospinal
190
What are the two limbs of the internal capsule and what are they separated by?
Which limb does the corticospinal tract pass through?
Anterior and posterior
Genu
Posterior
191
4 symptoms which occur when tracts are lost?
Paralysis, hyper-reflexia, hypertonia and Babinski
192
Define 'Brainstem Death'
Irreversible loss of capacity for consciousness and breathing
193
What cranial nerve does each reflex test test for?
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Pupillary light reflex: 2+3
Cotton wool in eye: 5+7
Vesibulo-occular reflex (turning head and eyes): 3,4,6+8
Gag reflex: 5+7
Cough reflex: 10
```
194
Which cranial nerves do not have their nuclei in the brainstem?
1 and 2
195
What are the three movements?
Reflex, rhythmic, voluntary
196
6 examples of reflexes
Spinal, posture, balance, innate movements, learned movements, goal-directed movements
197
3 characteristics of the alpha motor neurone
Wide axons, myelinated, long
198
Where can motor neurones receive information from?
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Muscle spindles (1a afferents)
Golgi and tendon organs (1b afferents)
Cutaneous skin receptors
Spinal interneurones
Upper motor neurones
```
199
What neurone degenerates in motor neurone disease?
Alpha motor neurone
200
5 symptoms of motor neurone disease
| 3 things that are unaffected
Muscle weakness, atrophy, twitching, difficulty breathing and swallowing
Cognitive, eyes and sensory
201
When do extrafusal muscle fibres contract?
| What do they contain?
Contract when the alpha motor neurone signals
| Contain muscle spindles
202
Where are intrafusal muscle fibres found?
| What do they detect?
Inside muscle spindles parallel to the extrafusal fibres
| They detect the amount and rate of muscle length change
203
What does the 1a afferent neurone provide information about?
Spindle stretch
204
What is the muscle spindle?
| What neurones innervate it?
A fibrous capsule found in muscle fibres
| 1a sensory and gamma motor neurones
205
2 roles of the gamma motor neurone
| What is it co-activated with?
Regulates the sensitivity of sensory afferents to stretch and intrafusal muscle contraction
Readjusts and maintains the tautness of the muscle spindle length
Always co-activated with alpha
206
Explain the knee jerk reflex:
Type of reflex
What is activated
Flexors vs extensors
Agonist vs Antagonist
A stretch reflex
Patellar tendon --> stretch quadriceps + activate 1a muscle spindle
If the flexors are excited then the extensors are inhibited causing movement
AGONIST: Contracted by the reflex
ANTAGONIST: Inhibitory interneurone inhibits hamstring movement
207
Where is the Golgi tendon organ?
What does it run parallel to?
What is it innervated by?
How is it activated?
In the junction between the muscle and the tendon
Runs parallel to the extrafusal fibres
Innervated by the 1b afferent
Increased tension in collagen fibres --> compression of sensory receptors and increase in 1b activity --> decrease in alpha motor neurone activity
208
How does the flexor withdrawal reflex work?
Step on something sharp
Nociceptive cutaneous receptors --> afferent --> inter --> alpha motor
Hamstring flex to pull leg away
AND Quadriceps flex on the other leg to extend the knee and balance
209
What are central pattern generators?
| What is the purpose of them?
Neural networks in the brain and spinal cord
| Allow you to automatically carry out OSCILLATORY (repetitive) movements (e.g. walking) without sensory feedback
210
What are the 3 layers of the muscle outer layer?
Which layer has the muscle fasicle and which has myosin and actin filaments?
Epimysium
Perimysium (Muscle Fascile)
Endomysium (Myosin and Actin)
211
What are the 3 bands of muscle?
| What do the words isotropic and anisotropic mean?
I band: Actin only (isotropic)
A band: Actin and Myosin (anisotropic)
H band: Myosin only
212
How are the ends of actin anchored to the z line?
By the enzyme alpha actinin
213
Where are satellite cells found?
Between the basement membrane and sarcolemma
214
What two types of chains is myosin made from?
Light and heavy
215
What 3 things is an actin molecule made from?
Tropomyosin regulatory proteins
Myosin binding site
Troponin complex
216
When is the maximum tension in a muscle?
When the muscle is at rest
217
What does the force of contraction depend on?
| What is it proportional to?
Depends on the degree of overlap
| Proportional to the muscle fibre length
218
What receptors are found at the NMJ in skeletal muscle?
Nicotinic cholinergic receptors
219
What is the muscle end plate potential?
| How is an action potential always made?
-90mV
| Many neurotransmitters
220
What is the sarcolemma in direct contact with?
The extracellular fluid
221
What forms a triad in the muscles?
T tubules surrounded by sarcoplasmic reticulum with a terminal cisternae on either side
222
When does Rigor Mortis end?
When proteolytic lysosomal enzymes released by autolysis digest the decomposing cells
223
How long does Rigor Mortis last for?
2-3 hours
| Can be 24 hours
224
3 ways that Calcium is taken back into the sarcoplasmic reticulum after muscle contraction
SERCA pump on Sarcoplasmic Reticulum (ATP)
Na-Ca exchanged
Ca pump
225
How is calcium stored in the sarcoplasmic reticulum?
Calsequestrin and Calreticulin
226
How is Calcium released from the sarcoplasmic reticulum?
Type-L calcium channels open (Dihydropyradine)
| These link to ryadonine receptors releasing calcium from the sarcoplasmic reticulum
227
What are the 3 phases of muscle twitch?
1. Lag phase: Time is taken for cross bridge formation
2. Contraction: Increased tension
3. Relaxation: Decreased tension
228
What is a motor unit?
The motor nerve and muscle fibres which it innervates
229
What are the 4 types of muscle twitch?
Single muscle twitch: Stimulate muscle separately
Temporal summation: Continue to stimulate the muscle before it is relaxed causing an increase in tension every time
Unfused tetanus: Stimulate the muscle at shorter intervals - no overall increase in tension
Fused tetanus: Stimulate at very short intervals - muscle tension increases in a straight line
230
What is the pre-load determined by?
The initial muscle length
231
What is isometric contraction?
| Example
Stimulate muscle and increase tension but NO muscle shortening
(e.g. pushing a wall)
232
What is isotonic contraction?
| Example
Stimulate muscle and increase tension and the muscle SHORTENS
(e.g. pushing a box)
233
What are the three muscle fibres?
Slow twitch fibres
Fast twitch fatigue resistant fibres
Fast twitch glycolytic fibres
234
```
Slow twitch fibres:
High or low oxygen?
Do they get fatigued easily?
Colour?
Myoglobin level?
Blood flow?
What movements do they allow?
```
```
High oxygen
Resistant to fatigue
Red
High myoglobin
Increased blood flow
Posture
```
235
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Fast twitch fatigue resistant fibres:
High or low oxygen?
Myoglobin level?
Colour?
Do they get fatigued easily?
```
High oxygen
Resistant to fatigue
Red/pink
Medium myoglobin
236
```
Fast twitch glycolytic fibres:
Colour?
Myoglobin level?
Blood flow?
Do they get fatigued easily?
```
White
Decreased myoglobin
Decreased blood flow
Get faigued easily
237
Defne myopathy
Muscle disease
238
Define Myostitis
Inflammation in the muscle
239
What is Muscular Dystrophy?
A inherited and progressive disease
240
What is Myasthenia?
Increased muscle weakness with exercise
241
What is Myotonia?
Faliure to relax the muscle?
242
Which ion channels are affected in channelopathies?
Na, K and Cl
243
What happens during the disease dystrophonia?
What gender is it more common in and why?
What happens to the muscles?
What is the average life expectancy?
A loose dystrophin complex --> fat deposition in muscles instead of protein deposition
Males (sex linked)
Progressive muscular weakness
Life expectancy = 30
