Phase 2 - Week 2 (Tendons, Shoulder), Phase 1 - Week 6 (Muscles, Muscle/Nerve Excitation), Phase 2 - Week 3 (Muscle, Elbow + Forearm, Nervous Control) Flashcards
(291 cards)
1
Q
List the bones of the shoulder
A
- Scapula
- Clavicle
- Humerus
2
Q
Describe the position of the scapula
A
Lies obliquely on the back/side of the thorax
3
Q
What type of bone is the scapula
A
Flat
4
Q
Describe the articulations made by the scapula
A
- Acromioclavicular joint - acromial end of of the clavicle and acromion of the scapula
- Glenohumeral joint - glenoid fossa of the scapula and head of the humerus
5
Q
List the distinct structural features of the scapula
A
- Acromion
- Coracoid process
- Glenoid fossa
- Inferior angle
- Infraspinous fossa
- Lateral Border
- Medial Border
- Neck of the glenoid
- Spine
- Superior border
- Subscapular fossa
- Supraspinous fossa
- Suprascapular notch
6
Q
Acromion
A
Large projection forming point of the shoulder, articulates with the clavicle
7
Q
Coracoid Process
A
Large anterior projection, provides insertion point for pectoralis minor and point of origin for short head of the biceps brachii and corcacobrachialis
8
Q
Glenoid Fossa
A
Shallow socket that articulates with the head of the humerus to form the shoulder joint
9
Q
Inferior angle
A
Junction between the medial and lateral borders, typically overlies 7th rib
10
Q
Infraspinous fossa
A
Large depression on the back of the scapula, below the spine, provides point of origin for the infraspinatus
11
Q
Lateral border
A
Thick border, runs from infraglenoid tubercle to inferior angle
12
Q
Medial border
A
Thin border between superior and inferior angles
13
Q
Neck of the glenoid
A
Constriction between glenoid + body of the scapula
14
Q
Spine of the scapula
A
Triangular ridge of bone that crosses the back of the scapula , from acromion to medial border
15
Q
Superior Angle
A
Junction between lateral + medial borders
16
Q
Superior Border
A
Thin, sharp border, separated from coracoid process by supraglenoid notch
17
Q
Subscapular fossa
A
Slightly ridged fossa on inner surface of the scapula. Point of origin for subscapularis muscle
18
Q
Supraspinous fossa
A
Deep fossa on back of scapula, above spine. Point of origin for supraspinatus muscle
19
Q
Subscapular notch
A
Dip in superior border, just medial to coracoid process
20
Q
Describe the shape and postition of the clavicle
A
Slightly S-shaped bone, lies at the base of the neck, in front of the first rib
21
Q
Describe the articulations made by the clavicle
A
- Acromioclavicular joint with the acromion of the scapula
2. Sternoclavicular joint with the manubrium of the sternum
22
Q
Describe the ends of the clavicle
A
- Sternal end = medial end of clavicle, articulates with the manubrium of the sternum
- Acromial end = lateral end of the clavicle, articulates with the acromion of the scapula
23
Q
Conoid tubercle of the clavicle
A
Small projection from posterior edge, gives attachment to the conoid part of the coracoclavicular ligament
24
Q
Describe the articulations made by the humerus
A
- Glenohumeral joint - head of the humerus with the glenoid fossa of the scapula
- Humeroulnar joint - trochlea of the humerus with the trochlear notch of the ulna
- Humeroradial joint - capitulum of the humerus with the head of the radius
25
List the distinct structural features of the humerus
1. Head
2. Anatomical neck
3. Greater tubercle
4. Lesser tubercle
5. Surgical neck
6. Intertubercular groove
7. Shaft
8. Deltoid tuberosity
9. Capitulum
10. Trochlea
11. Coronoid fossa
12. Radial fossa
13. Olecranon fossa
14. Medial epicondyle
15. Lateral epicondyle
26
Head of the humerus
Forms 1/3 of a sphere that articulates with the glenoid fossa of the scapula
27
Anatomical neck of the humerus
Constricted area that joins head to greater and lesser tubercles
28
Greater tubercle
Large projection from the lateral side of the proximal humerus
29
Lesser tubercle
Projection that provides an insertion point for the subscapularis muscle
30
Surgical neck
Junction between the tubercles and the shaft. Common site for fractures
31
Intertubercular groove
Located anteriorly between the tubercles, holds the tendon of the biceps brachii muscle. Sometimes called bicipital groove.
32
Shaft of the humerus
Long + thick shaft that connects the two extremities
33
Deltoid tuberosity
Roughened area, halfway down shaft. For the insertion of the deltoid muscle
34
Capitulum
Lateral of the two distal condyles, articulates with the radius
35
Trochlea
Medial of the two distal condyles, articulates with the ulna
36
Coronoid fossa
Anterior fossa above the capitulum for the head of the radius
37
Radial fossa
Anterior fossa above the capitulum for the head of the radius
38
Olecranon fossa
Large posterior fossa for the olecranon of the ulna
39
Medial epicondyle
Prominence medial to the trochlea, gives origin to the superficial flexor muscles in the forearm
40
Lateral epicondyle
Prominence located lateral to the capitulum gives origin to the extensor muscle in the forearm
41
List the muscles acting on the scapula
1. Pectoralis minor
2. Rhomboid major
3. Rhomboid minor
4. Trapezius
5. Serratus anterior
42
Give the origin, insertion and action of pectoralis minor
```
Origin = Ribs 3-5
Insertion = Coracoid process of the scapula
Action = Pulls shoulder girdle forwards + downwards
```
43
Give the origin, insertion and action of rhomboid major
```
Origin = T2-T5 spinous processes
Insertion = Medial border of the scapula
Action = Medially rotates + retracts the scapula
```
44
Give the origin, insertion and action of rhomboid minor
```
Origin = C7-T1 spinous processes
Insertion = Spine of the scapula
Action = Medially rotates the scapula and retracts the scapula
```
45
Give the origin, insertion and action of the trapezius
```
Origin = External protuberance of the occipital bone, nuchal ligament, C7-T2
Insertion = Clavicle, scapula
Action = Elevates + retracts the scapula and depresses its medial aspect, extends and laterally flexes the head and neck
```
46
Give the origin, insertion and action of serratus anterior
```
Origin = Ribs 1-9
Insertion = Costal surface of the medial border of the scapula
Action = Protracts the scapula and pectoral girdle
```
47
List the shoulder muscles acting on the humerus
1. Latissimus dorsi
| 2. Pectoralis major
48
Give the origin, insertion and action of latissimus dorsi
```
Origin = T7-T12 spinous processes, iliac crest of hip bone, ribs 9-12
Insertion = Intertubercular groove of the humerus
Action = Extends, adducts and medially rotates the arm at the shoulder joint
```
49
Give the origin, insertion and action of pectoralis major
```
Origin = Medial end of the clavicle, sternum, costal cartilages 1-6
Insertion = Intertubercular groove of the humerus
Action = Adducts and internally rotates the humerus, extends shoulder joint from flexed + flexes it from extended
```
50
List the rotator cuff muscles
1. Supraspinatus
2. Infraspinatus
3. Subscapularis
4. Teres minor
51
Give the origin, insertion and action of the supraspinatus
```
Origin = Supraspinous fossa of the scapula
Insertion = Greater tubercle of the humerus
Action = Initiates abduction of the arm
```
52
Give the origin, insertion and action of the infraspinatus
```
Origin = Infraspinous fossa of the scapula
Insertion = Greater tubercle of the humerus
Action = Laterally rotates the arm
```
53
Give the origin, insertion and action of the subscapularis
```
Origin = Subscapular fossa of the scapula
Insertion = Lesser tubercle of the humerus
Action = Medially rotates the arm
```
54
Give the origin, insertion and action of teres minor
```
Origin = Lateral border of the scapula
Insertion = Greater tubercle of the humerus
Action = Laterally rotates the arm, contributes to abduction of the arm
```
55
Give the origin, insertion and action of the deltoid
```
Origin = Clavicle, spine of the scapula, acromion of the scapula
Insertion = Deltoid tubersity of the humerus
Action = Adbucts the shoulder
```
56
Give the origin, insertion and action of the teres major
```
Origin = Inferior angle of the scapula
Insertion = Intertrabecular Groove of the humerus
Action = Extends the shoulder, adducts and medially rotates the humerus
```
57
Give the origin, insertion and action of the coracobrachialis
```
Origin = Coracoid process of the scapula
Insertion = Humerus
Action = Flexes the shoulder and adducts the arm
```
58
How are the upper limbs innervated
The brachial plexus supplies the entire upper limb with motor and sensory innervation
59
Describe the structure of the brachial plexus
1. Roots - C5-T1 spinal nerves
2. Trunks - superior, middle and inferior
3. Divisions - anterior and posterior
4. Cord - posterior, lateral and medial
5. Branches
60
Superior trunk of the brachial plexus
- Formed from roots of C5 + C6
| - Splits into anterior and posterior divisons
61
Middle trunk of the brachial plexus
- Formed from root of C7
| - Splits into anterior and posterior divisions
62
Inferior trunk of the brachial plexus
- Formed from the roots of C8 + T1
| - Splits into anterior + posterior divisons
63
Anterior divisions of the brachial plexus
The upper and middle anterior divisions form the lateral cord and the lower anterior division forms the medial cord
64
Posterior divisions of the brachial plexus
The posterior divisions of all three trunks combine to form the posterior cord
65
Posterior cord of the brachial plexus
- Formed by the posterior divisions of all three trunks
- Gives off branches:
1. Subscapular nerves
2. Thoracodorsal Nerve
3. Axillary nerve
4. Continues as radial nerve
66
Lateral Cord of the brachial plexus
- Formed by the anterior division of the inferior trunk
- Gives of branches:
1. Musculocutaneous nerve
2. Lateral pectoral nerve
3. Joins with the medial cord to form the median nerve
67
Medial cord of the brachial plexus
- Formed by the anterior divisions of the superior and middle trunks
- Gives off branches:
1. Medial pectoral nerve
2. Medial cutaneous nerve of the forearm
3. Medial cutaneous nerve of the arm
4. Ulnar nerve
5. Joins with the lateral cord to form the median nerve
68
List the terminal branches of the brachial plexus
1. Axillary nerve
2. Radial nerve
3. Musculocutaneous nerve
4. Ulnar nerve
5. Median nerve
69
Axillary nerve
```
Origin = C5/6, posterior cord
Course = descends behind the axillary artery + winds around the surgical neck of the humerus
Innervates = motor = deltoid + teres minor, sensory = shoulder joint, cutaneous = skin over the shoulder + lateral arm
```
70
Radial nerve
```
Origin = C5-T1 posterior cord of the brachial plexus
Course = exits axillae under teres minor, runs around back of humerus in the radial groove with the arteria profunda brachii. Passes down the lateral side of the forearm to the wrist
Innervates = motor = extensors of elbow, wrist + hand, sensory = elbow, wrist + hand joints, cutaneous = skin over the posterior surface of the upper limb
```
71
Musculocutaneous nerve
```
Origin = C5-7, lateral cord
Course = descends between biceps + brachialis to the elbow where it becomes the lateral cutaneous nerve of the forearm
Innervates = motor = flexors of the elbow joint, cutaneous = skin over the lateral border of the forearm
```
72
Ulnar nerve
```
Origin = C7-T1, medial cord
Course = descends the medial side of the arm in front of the medial head of triceps to reach the elbow. Enters the flexor compartment of the forearm + travels to the wrist
Innervates = motor = majority of the muscles of the hand, sensory = hand joints, cutaneous = skin of the medial aspect of the hand
```
73
Median nerve
Origin = C5-T1, medial + lateral cords
Course = leaves axillae with brachial artery, travels to the elbow. In the forearm, it travels to the wrist where it enters the carpal tunnel and divides into medial and lateral branches
- Innervates = motor = most of the flexor muscles in the forearm, cutaneous = skin of the elbow, wrist and radial aspect of the palm of the hand
74
List the 3 major arteries in the posterior scapular region
1. Suprascapular artery
2. Posterior circumflex artery
3. Circumflex scapular artery
75
Describe the function of tendons
Tough, fibrous structures that provide attachment for muscles to bones. Transmit the muscles' contractile force to bone, producing movement at joints.
76
Describe the arrangement of fibres in tendons
Collgen fibril --> Collagen fibre --> Primary collagen fibre bundle (sub-fascicle) --> Secondary fibre bundle (fascicle) --> Tertiary fibre bundle --> Tendon
77
Describe the connective tissue layers that surround tendons
```
Endotenineum = Surrounds primary, secondary and tertiary bundles to facilitate gliding
Epiteon = fine layer of connective tissue that sheathes tendon
Paratenon = loose elastice connective tissue layer, allows tendon to more against neighbouring tissues
```
78
How are tendons attached to bones?
By collagenous fibres (Sharpey fibres) that continue into the matrix of the bone
79
What type of collagen is found in tendons?
Type 1
80
List the cell types found in tendons
1. Tenocytes (fibrocytes)
| 2. Tenoblasts (fibroblasts)
81
Explain the role of tenocytes in tendons
Mature tendon cells - lay down type 1 collagen fibres.
82
Explain the role of tenoblasts in tendons
Immature tendon cells, give rise to tendons. Highly proliferative, involved in synthesis of collagen and other components of the ECM.
83
What aspect of tendon structure gives their tensile strength?
Collagen bundles in parallel arrangements gives tensile strength and elasticity in one direction.
84
Describe the components of the ECM of tendons
Elastin, proteoglycans, type 1 collagen
85
List the stages of tendon healing
1. Inflammation
2. Regeneration
3. Remodelling
86
How long does each stage of tendon healing last?
Inflammation lasts a week, regeneration lasts a month, remodelling lasts a year
87
Describe the pain felt during each stage of tendon healing
Pain occurs during:
- Inflammation even when at rest
- Regeneration under normal load bearing
- Remodelling with extreme load bearing
88
Describe the inflammation stage of tendon healing
1. Tendon ruptures/tears
2. BVs are also damaged, platelets in the blood become activated
3. Platelets release growth factors, trigger surrounding inflammatory cells - e.g. macrophages
4. OR - molecules from interior of cells that are ruptured from injury are released and recognised as foreign by the immune system, triggers the inflammatory response
- Inflammation is initially non-specific
89
Describe the regeneration stage of tendon healing
1. Macrophages stimulate reconstruction - summon endothelial cells that form new BVs + mesenchymal stem cells that start forming new ground substance with collagen
2. At first, type 3 collagen is laid down (rather than type 1) and is haphazardly organised (not in parallel bundles)
- new material looks like watery gel - pink coloured granulation
3. Becomes large nodule (tendon callus) which encloses the old injury site
90
Compare type 1 and type 3 collagen
Type 3 collagen can be quickly produced but is of a lower quality than type 1 - weaker and less elastic. Type 1 has a more complex structure which takes longer to synthesise but is stronger and more elastic.
91
Describe the remodelling stage of tendon healing
1. For the new tissue to perform like the old tendon did the collagen needs to be higher quality + be organised in neat parallel bundles aligned in the direction of strain
2. To know which way the direction of force is the cells detect the deformation cycle which occurs when muscles pull the damaged tendon - why load bearing/movement is important during healing
3. Cells break down the callus and replace it with a better, more functionally adapted material - primarily collagen type 1, in parallel arrangement
- Callus decreases in size, tissue left resembles original tendon
92
Tendinitis
Inflammation of the tendon (acute)
93
Treatment of tenditis
- Rest joint
- Take NSAIDs
- Physiotherapy
- Steroid injections, surgery, shock wave therapy (if more long-term)
94
Diagnosis of tendinitis
Physical examination
95
List the symptoms of tendinitis
- Pain - worse with movement
- Difficulty moving joint
- Feeling grating/crackling sensation when moving joint
- Swelling, sometimes w/ heat or redness
96
Describe methods of prevention of tendinitis
- Warm up before exercising, stretch afterwards
- Wear suitable shoes for exercise
- Take regular breaks from repetitive exercise
- Don't over-exercise tired muscles
- Don't do repetitive exercises
97
Tendinosis
Non-inflammatory degeneration of the tendon caused by micro-tears due to overuse
98
Complete tendon rupture
Tear of the tendon in which none remains intact
99
Partial tendon rupture
Tear of the tendon in which some remains intact
100
List the symptoms of tendon ruptures
- Swelling around joint
- Inability to bear weight
- Bruising
- Sudden, sharp pain at time of injury which develops into a dull ache
- Stiffness
- Snapping/popping sound at time of injury
101
Diagnosis of tendon ruptures
- Physical examination
- Check for range of movement/weight bearing etc.
- Ultrasound/MRI to show rupture
102
Describe the treatment of tendon ruptures
- Depends on partial or complete tear, age, health etc.
- All will have physiotherapy
- Non-surgical or surgical treatment options
103
Describe non-surgical treatment of tendon ruptures
- Plaster cast, brace on injury for 6-8 weeks to keen tendon immobile while it heals
- Crutches to reduce weight bearing
- Pain-relief/anti-inflammatories e.g. NSAIDs
104
Describe surgical treatment of tendon ruptures
- Often done if active/young/athlete
- Depends on where tendon is ruptured (e.g. if achilles tendon is ruptured at or above the point at which the tendon meets the calf muscle surgery may not be possible)
- Open surgery - one long incision to reach tendon and repair it
- Limited open surgery - make a single incision but it will be shortened
- Percutaneous surgery - number of small incisions to reach tendon and repair it
- Tendon is stitched together to allow more efficient healing
- Chance tendon will rupture again after surgery
105
How are muscles attached to bones?
Directly via tendons, indirectly via aponeurosis
106
Describe the macrostructure of a muscle
Origin -> belly -> insertion
(From smallest to largest structure)
1. Myofilaments (proteins responsible for muscle contraction)
2. Myofibrils (tubes of proteins)
3. Muscle fibres (muscle cells)
4. Muscle fascicles
5. Skeletal muscle
107
Describe the function of muscles
Able to:
- Contract
- Respond to stimulation from nervous system
- Stretch beyond normal resting length
- Revert to normal resting length
108
List the layers of connective tissue found in muscles
1. Endomysium
2. Perimysium
3. Epimysium
109
Endomysium
- Thin layer of connective tissue
| - Surrounds each muscle fibre (cell)
110
Perimysium
- Thick connective tissue
- Groups muscle fibres into fascicles
- Protects fascicles from damage, contains capillaries + nerve fibres - allows nutrient transfer
111
Epimysium
- Thick connective tissue
- Surrounds whole skeletal muscle
- May continue beyond muscle belly as tendon and become continuous with periosteum of bone
- Separates muscle from surrounding tissues and organs
112
List the components of skeletal muscle fibres (cells)
1. Nuclei
2. Sarcoplasm
3. Myofibrils
4. Terminal cisternae
5. Sarcoplasmic reticulum
6. Transverse tubules
7. Sarcolemma
113
What is the sarcolemma of a muscle fibre?
- Plasma membrane of a muscle fibre
| - Invaginated to from transverse tubules
114
What are the transverse tubules of a muscle fibre?
- Sarcolemma is invaginated to form transverse tubules (T tubules)
- Penetrate through the fibre, conduct electrical stimuli from sarcolemma
115
Nuclei of muscle fibres
- Each cell contains multiple flattened nuclei
| - Lie beneath sarcolemma
116
Describe the sarcoplasmic reticulum of a muscle fibre
- Type of smooth endoplasmic reticulum
- Only found in skeletal muscle cells
- Large, concentrated store of calcium
117
Describe the role of the terminal cisternae of a muscle fibre
- Sarcoplasmic reticulum becomes enlarged, forms bonds, wrap around muscle fibres on either side of T tubules
- Action potential, T tubule stimulates terminal cisternae to release calcium from sarcoplasmic reticulum - triggers contraction of myofibrils
118
What is the sarcoplasm of a muscle fibre?
- Cytoplasm
| - Large amounts of glycogen (provides energy during muscle contraction), and myoglobin (contains stored oxygen)
119
What are the myofibrils of a muscle fibre?
- Thread-like organelles extend length of muscle fibre
- Each myofibril made of bundles of myofibrils which are arranged into contractile elements of muscle cell i.e. the sarcomere
120
Sarcomere
- Basic functional unit of a myofibril
- Made of contractile proteins
- Supported by structural and elastic proteins
- Have thin and thick actin and myosin filaments, when triggered by release of calcium, actin and myosin filaments slide over each other to shorten sarcomere (contraction)
121
List the bands/lines/zones of the sarcomere
1. I band
2. Z-line
3. M-line
4. H-zone
5. A-band
122
I band of the sarcomere
- Isotropic = uniform in each direction
- Lighter band
- Only thin actin filaments
- Bisected by thin, dark Z-line
123
Z-line of the sarcomere
- Dense protein disc
- Defines end of each sarcomere
- Composed of large elastic protein titin - provides anchorage for thin filaments + coiled elastic titin filaments
- Titin filaments aid elastic recoil of muscle during relaxation
124
M-line of the sarcomere
- Thin, elastic mesh of interlinking thick fibres
| - At centre of sarcomere
125
H-zone of the sarcomere
- Lighter region of each A band
| - Only myosin filaments - deficient in actin filaments
126
A-band of the sarcomere
- Anisotropic = directionally dependent
| - Dark band consisting of parallel, thick filaments with tin filaments partly overlapping them
127
List the regulatory proteins found in the sarcomere
1. Myosin
| 2. Actin
128
Myosin
- Contractile proteins
- Thick filaments
- Mainly in A-band + H-zone of the sarcomere
- Interacts with actin to create movement
- Made of three domains - head, neck + tail
129
Describe the function of myosin
- Coupling hydrolysis of ATP to conformational changes in head region of filament
- Enables binding and movement along actin filament
130
Actin
- Contractile protein
- Thin filaments
- Each microfilament is a polymer called F actin, composed of monomeric subunits called G actin
- F actin polymer are made of G actin subunits twisted together
- All actin filaments same length + contain myosin binding sites - myosin heads attach and walk along, causing contraction
131
Describe the function of actin filaments
To bind to myosin
132
List the regulatory proteins of the sarcomere
1. Tropomyosin
| 2. Troponin
133
Tropomyosin
- Regulates actin filaments
- Tropomyosin filaments - long molecule made of coil of alpha helices
- Twist around each filament of actin, bind to it in 7 places
- Function - uncovering of myosin head binding sites on actin during excitation (contraction coupling)
134
Troponin
- Regulates actin filaments
- Moves tropomyosin away from myosin binding site on actin filaments
- 3 subunits - TnT, TnI + TnC
- Calcium binding to troponin causes conformational shape change that moves troponin away from myosin head binding sites on actin, also moves tropomyosin away from myosin head binding sites, freeing them for cross bridge formation
135
TnT subunit of Troponin
Binds to tropomyosin near the ends of the tropomyosin sub-units
136
TnI subunit of Troponin
Binds to actin filaments
137
TnC subunit of Troponin
Binds to TnI + TnT subunits and calcium ions
138
What is the role of the structural proteins of the sarcomere?
- Contribute to overall stability and elasticity of myofibrils
- Hold thick + thin filaments in alignment
- Connect sarcolemma to ECM
139
List the structural proteins of the sarcomere
1. Titin
2. Nebulin
3. Alpha actinin
4. Myomesin
5. Dystrophin
140
Titin
- Regulatory component of sarcomere
- Large singular protein coiled at one end
- Between M-line and Z-line of sarcomere
- Act as spring for actin filaments, attaching them to Z-line
141
Nebulin
- Structural component of actin
- Sheath-like protein, covers entire actin filament
- Anchors filaments to Z-lines
142
Alpha actinin
- Makes up Z-lines of sarcomere
- Made of analogous dense bodies in smooth muscle
- Helps anchor actin filaments
143
Myomesin
- Makes up M-line of sarcomere
| - Attaches myosin thick filaments to each other at M-line
144
Dystrophin
- Links actin filaments to sarcolemma
- Transmits tension generated in sarcomere to tendon of muscle
- Reinforces strength of sarcolemma
145
Explain how the sliding filament mechanism resulting in contraction of the sarcomere
- Allows skeletal muscle to contract and relax
- Movement of thick and thin filaments relative to each other causes shortening of muscle fibre
- Contraction occurs because thick (myosin) filaments bind to thin (actin) filaments by chemical bonds called cross-bridges. Myosin filaments walk along actin filaments, pull them towards centre of sarcomere
- Causes contraction because actin is attached to Z-line + myosin grip along, making H-zone almost non-existent
- Combined shortening of many sarcomeres along number of myofibrils causes whole muscle contraction
146
Describe the differences in the appearance of sarcomeres in relaxed muscle compared with contracted muscle
```
Relaxed muscle:
- Sarcomeres have few cross-bridges
- H-zone is large, I band is large
Contracted muscle:
- Sarcomeres have many cross-bridges
- H-zone is small or non-existent
- I-band is smaller
- A-band remains the same
```
147
What happens to the length of the A-band when the sarcomere contracts and why?
A-band is constant length contracted or relaxed as length of myofilaments doesn't change during contraction
148
Which cells stimulate muscle excitation?
Somatic motor neurons/efferent neurons
149
How is muscle excitation triggered?
Neurones propagate action potentials - series of electrical events involving plasma membrane, altering from resting state
150
What is required for an action potential to be triggered at the neuromuscular junction?
If the stimulus reaches a threshold value sufficient to open voltage-gated ion channels in cell's plasma membrane - resting membrane potential less negative
151
What is the effect of stimulation of a muscle at the neuromuscular junction?
Excitation-contraction coupling and muscle fibre contraction
152
Describe the efferent neurones at the neuromuscular junction
- Terminate on the surface of muscles
- Bulb-like processes
- Relay impulses from CNS -> effector organs, muscles or glands
153
Where does muscle excitation begin?
Neuromuscular junction = connection between muscle and neurone
154
Describe the presynaptic membrane at the neuromuscular junction
- Form synaptic end bulbs at end of branches of axon of motor neurone
- At motor end plate of fibre
- Contain synaptic vesicles filled with acetyl choline (neurotransmitter), which is released in response to action potential to stimulate adjoining neuron or motor end end
155
Synaptic cleft
Small gap between the communicating somatic neurone or motor end plate
156
Motor end plate
- Part of muscle fibre innervated by somatic motor neurone
- Highly excitable area
- Contains many acetyl choline receptors
- Contains junctional folds for larger surface area for neurotransmitter binding
157
List the sequence of events which occur at the neuromuscular junction
1. Action potential received
2. Fusion of synaptic vesicles to presynaptic membrane
3. Movement of acetyl choline across synaptic cleft, binding to postsynaptic membrane
4. Sodium influx
5. Depolarisation of postsynaptic membrane
6. Breakdown and removal of acetyl choline from synapse
158
Describe how the action potential is received at the presynaptic membrane terminal and the effect this has
- AP propagated along presynaptic motor neurone to presynaptic axon terminal
- Causes voltage-gates calcium channels to open, triggering influx of calcium ions from extracellular fluid
159
Describe fusion of synaptic vesicles to the presynaptic membrane
High calcium concentration causes axon's synaptic vesicles containing acetyl choline to fuse with the presynaptic membrane and release acetyl choline into the synaptic cleft in a process called exocytosis
160
Describe the effect of acetyl choline binding to the postsynaptic memrbane
- Acetyl choline diffuses across synapse to motor end plate, activating acetyl choline receptors on post-synaptic membrane
- Receptors are ligand-gated channels - undergo conformational change when acetyl choline binds
- Shape change opens channels, allowing influx of cations (mostly sodium ions) down electrochemical gradient, across postsynaptic membrane into muscle cell's sarcoplasm
161
Describe the effect of the influx of sodium ions on the post-synaptic membrane
- Influx of positively charged sodium ions causes sarcoplasmic side of post-synaptic membrane to become more positive, causing a change in membrane potential
- Change elicits muscle action potential, propagated along sarcolemma and into T tubules
- As action potential is conducted deep into muscle fibre, ryanodine receptors on surface of sarcoplasmic reticulum trigger release of calcium ions - begins process of muscle contraction
162
Describe the breakdown and removal of acetyl choline from the synapse
- Neurotransmitters left in synapse after synaptic transmission may affect subsequent synaptic events - have to be removed from synaptic cleft
- Broken down by acetylcholinesterase (AChE) a degrading enzyme - breaks down acetyl choline into inactive acetate and choline molecules - transported back through uptake into presynaptic terminals - recycled to synthesis new acetyl choline molecules or removed from cleft by neuroglia
163
Excitation-contraction coupling
- Somatic motor neurones stimulate contraction - more stimulation = more contraction
- Excitation-contraction coupling = electrical stimulus from nerve fibre ending translates into contraction of muscle
- Takes place within sarcoplasm of muscle fibre, mediated by calcium ions
164
List the steps in excitation-contraction coupling
1. Stimulus
2. Calcium release
3. Exposure of myosin binding sites
4. Calcium Storage
165
Describe the initial stimulation and calcium release during excitation-contraction coupling
1. Stimulus
- AP at neuromuscular junction, travels through sarcolemma and the transverse tubules to the terminal cisternae of the sarcoplasmic reticulum which has reservoirs of calcium for muscle contraction
2. Calcium release
- Reception of AP triggers opening of calcium release channels in membrane of sarcoplasmic reticulum - calcium ions flow out into cytosol of muscle fibre
166
Explain the process of exposure of the myosin binding sites during excitation-contraction coupling
- Calcium travels towards thick + thin filaments, binds to calcium binding sites on TnC subunit of troponin
- Calcium binding causes shape change in troponin
- Troponin is bound to tropomyosin
- Tropomyosin = regulatory protein, covers myosin binding sites on actin filament
- Conformational change in troponin causes conformational change in tropomyosin, uncovering myosin binding sites on actin
167
Explain the process of calcium storage in excitation-contraction coupling
- No more stimuli received by muscle fibre
- Calcium release channels close
- Intracellular calcium levels return to normal
- Calcium restored to reservoirs in sarcoplasmic reticulum by active transport pumps in its membrane
- Pumps transport calcium, against concentration gradient, into sarcoplasmic reticulum for storage
168
List the steps of the muscle contraction cycle
1. ATP hydrolysis
2. Cross-bridge formation
3. Power stroke
4. Detachment of myosin from actin
169
Describe the first step of the muscle contraction cycle
- ATP hydrolysed when it binds to ATP binding site on head of myosin filament
- Hydrolysis of ATP causes conformational change in orientation of myosin head - brings it closer to actin filament
- Phosphate group lost, ADP stays attached to myosin head
170
Describe cross-bridge formation in the muscle contraction cycle
- Myosin head is free to attach to actin filaments, form cross-bridges
- Myosin head attaches to actin filament, remaining phosphate group released
171
Describe the power stroke of the muscle contraction cycle
- Myosin head starts to pivot and rotate, releasing ADP
| - Generates force, pulls thin filament to centre of sarcomere, prepares myosin head to receive another ATP molecule
172
Describe the detachment of myosin from actin in the muscle contraction cycle
New ATP binds to ATP binding site on myosin head - detaches from binding site on actin filament, ready for ATP hydrolysis
173
What is the resting membrane potential?
- The electrical gradient across the cell membrane
| - Between -40mV and -90mV in nerve and muscle cells
174
How is the resting membrane potential maintained in cells
- 3 sodium ions are pumped out and 2 potassium ions are pumped in by the sodium-potassium pump (Na+/K+ ATPase)
175
What is the actual resting membrane potential of cells and why?
Approx. -70mV as a small amount of sodium ions leak into the cell
176
Motor unit
All the muscle cells controlled by one nerve cell
177
Muscle tonus
Tightness of a muscle
178
Tetany
Sustained contraction of a muscle, result of a rapid succession of nerve impulses
179
Refractory peroid
Brief period of time in which muscle cells will not respond to a stimulus
180
Skeletal muscle
- Long cylindrical cells
- Many nuclei per cell
- Striated
- Voluntary
- Rapid contractions
181
Cardiac muscle
- Branching cells
- One or two nuclei per cell
- Striated
- Involuntary
- Medium speed contractions
182
Smooth muscle
- Fusiform cells
- One nucleus per cell
- Nonstriated
- Involuntary
- Slow, wave-like contractions
183
List the types of muscle
- Smooth
- Cardiac
- Skeletal
184
Muscle hypertrophy
Increase in total mass of a muscle, results from an increase in size/number of individual muscle fibres
185
Muscle atrophy
Decrease in total mass of a muscle
186
What type of movements produce the most muscle hypertrophy
- When muscle is 'loaded' during contractions (e.g. lifting weights)
- Few strong contractions per day = significant hypertrophy of muscle in 6-10weeks
187
Describe the process of muscle hypertrophy
- Rate of synthesis of muscle contractile proteins greater when hypertrophy is developing, leading to greater number of myosin and actin filaments in the myofibrils
- Some myofibrils split within hypertrophying muscle to form new myofibrils - enlarge then divide longitudinally so fibrils become more numerous
- Enzyme systems providing energy also increase - enzymes of glycolysis, allowing for rapid supply of energy during short-term forceful contractions
188
List the requirements for muscle hypertrophy
1. Positive energy balance - consuming more calories than burned - needed for anabolism, therefore muscle hypertrophy
2. Increased requirement for protein - esp. branched chained amino acids, required for elevated protein syntesis
3. Training variables (strength training) - frequency, intensity, total volume affect
189
Define muscle fatigue
Inability to maintain muscle power output - reversible by rest. Has fast onset and fast recovery. There are several types but all reduce muscle force, shortening velocity and relaxation rate. Force loss occurs earliest and is greatest.
190
How does muscle fatigue differ from injury?
Fatigue is quickly reversible by rest - injury requires much longer recovery
191
List the types of muscle fatigue
1. Central fatigue (within the CNS)
| 2. Peripheral fatigue
192
Describe central fatigue
- Not muscular
- Loss of excitability in the motor cortex
- Upper motor problem - probably affected by sensory inputs from metabo-receptors in muscle
- Can also include failure of transmission in peripheral nerve + NMJ (pathological)
- Common in occupational work/recreational sport
- Sensation = discomfort/lack of motivation
- Probably not a factor in elite sport - athletes have better potassium metabolism
193
Describe peripheral fatigue
- Failure of excitation-contraction coupling, T tubule action potential, sarcoplasmic reticulum activation, calcium ion release
- Leads to failure of force generation at cross bridges
- Failure of ATP generation by depletion of energy stores
194
List common misconceptions about the causes of fatigue
- Fatigue is not due to lack of ATP - ATP concentrations increase during exercise
- Lactic acid is not the cause of fatigue
195
List the causes of fatigue
- ADP, phosphate + hydrogen ion concentration increase as ATP is broken down
- High concentration affects calcium pumping process and ATPase function
- Hydrogen competes with calcium for troponin binding
- Phosphate, ADP and hydrogen inhibit calcium ion release and calcium re-uptake into sarcoplasmic reticulum which affects force and speed of shortening and relaxation
196
Describe how muscles are supplied with energy in activities lasting a few seconds (short duration/high power)
- ATP is regenerated by breakdown of creatine phosphate
- Creatine phosphate -> creatine by creatine metabolism and ADP -> ATP
- Uses inefficient anaerobic glycolytic metabolism (produces 2 ATP)
197
Describe how muscles are supplied with energy in activities lasting longer than a few seconds up to 3 hours
- Glycogen metabolism:
- Glycogen -> glucose-1-phosphate -> glucose-6-phosphate (by enzymes glycogen phosphorlyase + phosphoglucomutase)
- Glucose-6-phosphate follows normal glycolysis to produce pyruvate (+ 2 ATP + 2NADH)
- Products of glycolysis go on to Krebs cycle + electron transport chain
- Net product = 36 ATP
198
Describe how muscles and supplied with energy in activities lasting longer than 3 hours (long duration/low power)
- Lipid metabolism starts after 90% of initial glycogen has been used
- Lipids come from adipocytes and intramuscular stores
- Very long duration activities utilise lipids almost entirely
1. Triglycerols -> fatty acids + glycerol
2. Fatty acids -> acetyl CoA
3. Acetyl CoA follows normal Krebs cycle + ETC
199
Strength training
- Small numbers of repetitions, high force contractions
- Loads close to max, 10-20 reps. per session
- Increases muscle mass (type 1 fibres)
200
Endurance training
- Large numbers of repetitions, low force contractions
| - Can decrease muscle mass (type 1 unused so will atrophy, type 2 don't increase muscle mass)
201
List the stages of strength training involved with muscle hypertrophy
1. Neural
| 2. Hypertrophic
202
Neural stage of strength training
- First 4-6 weeks
- Activation of motor units
- CNS response - increased recruitment of largest motor units + higher maximal firing rates
203
Hypertrophic stage of strength training
- Significant hormonal changes - After strenuous training, GH, local GFs (IGFs etc.), insulin and testosterone elevated
- Causes hypertrophy of muscle fibres
- Connective tissues also strengthen to cope w/ increasing forces
- Hypertrophy is slow - starts with development of new contractile filaments added laterally to existing myofibrils
- Later there is fibril splitting. Most enlarged fibrils divide longitudinally, fibrils become more numerous
204
Describe the effects of endurance training
- Mostly aerobic metabolism
- Improved cardiovascular performance
- Improved metabolic performance
- Selective hypertrophy of type 2A + B fibres
205
Describe the ways in which cardiovascular performance is improved by endurance training
Improves:
- Oxygen delivery
- Cardiac output
- Regional flow
- Capillary density
- Blood volume
206
Describe the ways in which metabolic performance is improved by endurance training
Improves:
- Enzyme concentrations
- Mitochondria density
- Substrate storage
- Mobilisation
207
List the types of muscle fibres
Type 1 = slow
Type 2A = fast fatigue resistant
Type 2B = fast fatiguing
208
Compare the twitch capabilities of:
a) Type 1
b) Type 2A
c) Type 2B
muscle fibres
a) Smaller twitch
b) Larger twitch
c) Largest twitch
209
Compare the rate of fatigue of:
a) Type 1
b) Type 2A
c) Type 2B
muscle fibres
a) Slower fatigue
b) Moderate fatigue
c) Fast fatigue
210
What colour are:
a) Type 1
b) Type 2A
c) Type 2B
muscle fibres
a) Red
b) Red
c) White
211
What type of respiration is used by:
a) Type 1
b) Type 2A
c) Type 2B
muscle fibres
a) Aerobic
b) Anaerobic + aerobic
c) Anaerobic
212
Compare the number of mitochondria and level of myoglobin found in:
a) Type 1
b) Type 2A
c) Type 2B
muscle fibres
a) Lots of myoglobin (therefore lots of oxygen) and high numbers of mitochondria
b) Moderate number of mitochondria and some myoglobin
c) Low level of myoglobin, few mitochondria
213
List the regions of the mesoderm
1. Paraxial mesoderm
2. Intermediate mesoderm
3. Lateral plate mesoderm
214
Paraxial mesoderm
- Forms from cells moving bilaterally and cranially from the primitive streak
- Lies adjacent to notochord and neural tube
- Forms somites
215
What is formed by the intermediate mesoderm
The genitourinary system
216
Lateral plate mesoderm
Split by a cavity (intraembryonic coelom) into two layers:
1. Somatic or parietal layer
2. Splanchnic or visceral layer
217
Which part of the mesoderm do skeletal muscles originate from?
Paraxial mesoderm
218
Which part of the mesoderm does smooth muscle (gut and derivatives) originate from?
Visceral layer, lateral plate mesoderm around gut tube
219
Which part of the mesoderm does smooth muscle (pupil, mammary and sweat glands) originate from?
Ectoderm
220
Which part of the mesoderm does cardiac muscle originate from?
Visceral layer, lateral plate mesoderm around heart tube
221
Which genes control somitogenesis?
- FGF family
- Wnt
- Notch
222
Which part of the mesoderm forms somites?
Paraxial mesoderm gets organised into segments - somites
223
How can the number of somites be used to determine the age of an embryo?
- Somites appear at a rate of approximately 3 pairs a day until the end of week 5
- Can accurately determine the age of an embryo by the number of pairs
224
How many pairs of somites are present by the end of week 5 of development?
42-44 pairs
- 4 occipital
- 8 cervical
- 12 thoracic
- 5 sacral
- 5-7 coccygeal
225
What is a somite?
A block of paraxial mesoderm which gives rise to skeletal muscles
226
Describe the process of epithelialisation of somites
- Segmented blocks of paraxial mesoderm are transformed into spheres
- Epithelial cells around a lumen
227
Describe differentiation of somites
- Cells in the ventral and medial area undergo and epithelial mesenchymal transition - become sclerotome (form vertebrae and ribs)
- Cells in dorsal half form dermomyotome
- Dermomyotome splits again to form dermatome (dermis of back) and myotome (muscles)
228
What is responsible for regulation of muscle development in embryos?
MYOD and MY45
- Transcription factors
- Activate muscle-specific genes
- Enable the differentiation of myogenic precursor cells in the dermomyotome into myoblasts
229
Myoblasts
- Myotome cells - committed muscle cell precursors
| - Undergo cell division under the influence of growth factors
230
What happens to myoblasts when growth factors are depleted?
- Stop dividing
- Secrete fibronectin onto ECM bind to it via an integrin - crucial step
- Align into chains and fuse, cell membranes disappear - multinucleated myotubes - primary myotubes
231
How is differentiation of of myoblasts mediated?
Myogenin mediates the differentiation of myoblasts
232
MYF5
- Required for myoblast formation
| - Inactivates MYF5 in mice results in delayed development in the intercostal and paraspinal regions
233
What is the effect of mutation in MYF5 and MYOD1
Loss of function mutation results in a complete lack of skeletal muscle formation
234
Where is smooth muscle found?
- Walls of GI tract
- Walls of arteries and veins
- Around glands
235
Describe smooth muscle development
- Originates from splanchnic mesoderm (except ciliary musce, sphincter pupilae of eye - ectoderm)
- Serum response factor (SRF) is responsible for smooth muscle cell differentiation
- SRF upregulated by kinase phosphorylation pathways
- Myocardin/myocardin related transcription factors enhance SRF activity
236
How do myoblasts for skeletal muscle?
- Myoblasts fuse to form long multinucleated fibres - myotubes
- Skeletal muscle = striated, contain many mitochondria
237
Describe the the development of tendons
Tendons are derived from the sclerotome under the control of the transcription factor scleraxis
238
Describe the development of cardiac muscles
- Originates from splanchnic mesoderm surrounding the developing heart tube
- Striated - different from skeletal
- Myoblasts adhere to each other via intercalated discs
239
List the articulations of the elbow joint
1. Humeroulnar -trochlear notch of the ulna and trochlea of the humerus
2. Humeroradial -head of the radius and capitulum of the humerus
240
List the important bony landmarks of the elbow joint
- Medial epicondyle (medial side of distal humerus)
- Lateral epicondyle (lateral side of distal humerus)
- Olecranon (proximal end of ulnar, point of elbow)
241
List the ligaments found in the elbow
- Radial collateral ligament (from lateral epicondyle)
| - Ulnar collateral ligament (from medial epicondyle)
242
Describe the blood supply to the elbow joint
Arterial supply = cubital anastamosis (branches of the brachial and deep brachial arteries)
243
Describe the innervation of the elbow joint
Median, musculocutaneous and radial nerves anteriorly and ulnar nerve posterior;y
244
List the movements of the elbow joint
```
Extension = triceps brachii and anconeus
Flexion = Brachialis, biceps brachii, brachioradialis
```
245
Which joints are responsible for movements of the forearm?
- Elbow joint (humeroulnar and humeroradial)
- Proximal radioulnar
- Distal radiaoulnar
246
Describe the position of the proximal radioulnar joint
Located immediately distal to the elbow joint, enclosed within the same articular capsule
247
Describe the articulation of the proximal radioulnar joint
Articulation between the head of the radius and the radial notch of the ulnar
248
Which ligament stabilises the proximal radioulnar joint?
The annular radial ligament - forms a collar around the joint
249
List the types of movement possible at the proximal radioulnar joint
1. Pronation = pronator quadratus and pronator teres
| 2. Supination = supinator and biceps brachii
250
Describe the location of the distal radioulnar joint
Located just proximally to the wrist joint
251
Describe the articulation of the distal radioulnar joint
Articulation is between the ulnar notch of the radius and the ulnar head
252
Describe the ligament which stabilises the distal radioulnar joint
Articular disk:
- Fibrocartilaginous ligament
- Binds the radius and ulna together, holds them together during movement at the joint
- Separates the distal radioulnar joint from the wrist joint
253
List the movements possible at the distal radioulnar joint
1. Pronations -pronator quadratus and pronator teres
| 2. Supination - supinator and biceps brachii
254
Interosseous membrane
- Sheet of connective tissue that joins the radius and ulna together between the radioulnar joints
- Spans between the medial radial border and the lateral ulnar border
255
List the functions of the interosseous membrane
1. Holds the radius and ulnar together during pronation and supination, provides stability
2. Acts as a site of attachment for muscles of the forearm
3. Transfers forces from radius to ulna
256
List the divisions of the muscles in the anterior department of the forearm
1. Superficial
2. Intermediate
3. Deep
257
In general, what movements are the muscles of the anterior compartment of the forearm responsible for?
Flexion at the wrist and fingers and pronation of the forearm
258
List the muscles of the superficial compartment of the anterior forearm
1. Flexor carpi ulnaris
2. Palmaris longus
3. Flexor carpi radialis
4. Pronator teres
259
Where do the superficial muscles of the anterior forearm originate from?
All originate from the medial epicondyle of the humerus
260
Describe the innervation of the superficial muscles of the anterior forearm
Ulnar nerve = flexor carpi ulnaris
Median nerve = Palmaris longus, flexor carpi radialis, pronator teres
261
List the movements of the superficial muscles of the anterior forearm
Flexor carpi ulnaris = flexion/adduction at wrist
Palmaris longus = flexion at wrist
Flexor carpi radialis = flexion and abduction at wrist
Pronator teres = pronation of forearm
262
List the muscles of the intermediate compartment of the anterior forearm
Flexor digitorum superficialis
263
Why is the flexor digitorum superficialis a good anatomical landmark?
The median nerve and ulnar artery pass between its two heads, then travel posterior
264
List the attachments of the flexor digitorum superficialis
- 2 heads - one from medial epicondyle of humerus, one from radius
- Splits into 4 tendons in wrist, travel through carpal tunnel, attaches to middle phalanges of fingers
265
Describe the actions of the flexor digitorum superficialis
Flexion of metacarpophalangeal joints and proximal interphalangeal joints and flexion of the wrist
266
Describe the innervation of the flexor digitorum superficialis
Median nerve
267
List the muscles of the deep compartment of the anterior forearm
1. Flexor digitorum profundus
2. Flexor pollicis longus
3. Pronator quadratus
268
Describe the actions of the muscles of the deep compartment of the anterior forearm
1. Flexor digitorum profundus = flexion of distal interphalangeal joints, metacarpophalageal joints and wrist
2. Flexor pollicis longus = Flexion of interphalangeal joint and metacarpophalangeal joint of the thumb
3. Pronator quadratus = pronation of the forearm
269
Describe the innervation of the muscles of the deep compartment of the anterior forearm
1. Flexor digitorum profundus = medial half by ulnar nerve, lateral half by median nerve
2. Flexor pollicis longus = median nerve
3. Pronator quadratus = median nerve
270
What is the general function of the muscles of the posterior forearm?
Produce extension at the wrist and fingers
271
Describe the innervation of the muscles of the posterior forearm
Radial nerve
272
How can the muscles of the posterior forearm be divided?
2 layers - deep and superficial, separated by a layer of fascia
273
List the muscles of the superficial layer of the posterior forearm
1. Extensor carpi radialis brevis
2. Extensor digitorum
3. Extensor carpi ulnaris
4. Extensor digiti minimi
5. Extensor carpi radialis longus
6. Anconeus
7. Brachioradialis
274
Which of the four muscles of the superficial layer of the posterior forearm attach to the lateral epicondyle?
1. Extensor carpi radialis brevis
2. Extensor digitorum
3. Extensor carpi ulnaris
4. Extensor digiti minimi
275
Describe the actions of the muscles of the superficial layer of the posterior forearm
Brachioradialus = Flexes elbow
Extensor carpi radialis longus/brevis = extend and abduct the wrist
Extensor digitorum = Extends fingers at MCP and IP joints
Extensor digiti minimi = Extends little finger, contributes to extension of wrist
Extensor carpi ulnaris = extension and adduction of wrist
Anconeus = extends elbow joint, abducts ulna during pronation
276
List the muscles of the deep layer of the posterior forearm
1. Supinator
2. Abductor pollicis longus
3. Extensor pollicis brevis
4. Extensor pollicis longus
5. Extensor indicis proprius
277
Describe the actions of the muscles of the deep layer of the posterior forearm
Supinator = supination
Abductor pollicis longus = abducts the thumb
Extensor pollicis brevis = extension at MCP and CM joints of thumb
Extensor pollicis longus = extends all joints of thumb
Extensor indicis proprius = extends index finger
278
Describe the arterial supply to the forearm and hand
In the distal cubital fossa the brachial artery bifurcates into radial (posterior) and ulnar (anterior) arteries which anastomose in the hand, forming two arches - superficial palmar arch and deep palmar arch
279
List the types of nerve cells which peripheral nerves contain axons from
1. Sensory neurones (afferents)
| 2. Motor neurones (efferents)
280
How many pairs of cranial nerves are there?
12 pairs
281
How many pairs of spinal nerves are there?
31 pairs
282
Describe the segmental arrangement of the spinal nerves
```
Cervical = 8
Thoracic = 12
Lumbar = 5
Sacral = 5
Coccygeal = 1
```
283
List the plexuses formed by the spinal nerves
- Cervical plexus (C1-C5)
- Brachial plexus (C5-T1)
- Lumbosacral plexus (T12-S5)
284
What is innervated by the brachial plexus and which nerves does it form?
```
Innervation of the upper limb
Nerves =
- Axillary
- Musculocutaneous
- Radial
- Ulnar
- Median
```
285
Describe the types of axons in peripheral nerves
Myelinated = large axon diameter, fast conduction velocities, for touch, vibration, motor
Unmyelinated = small axon diameter, slow conduction velocities, for pain, cold, hot
286
List the types of peripheral receptors and their modalities
- Mechanoreceptors = mechanical deflection, touch
- Thermoreceptors = hot/col
- Nociceptors = noxious (pain)
- Special sensory = vision, taste, olfaction
287
Myotome
Each muscle is supplied by a particular level/segment of the spinal cord and by its corresponding spinal nerve
288
Dermatome
An area of skin innervated by a particular level/segment of the spinal cord and its corresponding spinal nerve
289
Describe the pathway for voluntary movement
Motor cortex (upper motor neurone) -> brainstem/spinal cord (lower motor neurone) -> muscle -> movement
290
Describe the reflex pathway
No upper motor neurone component
Brainstem/spinal cord -> muscle
291
Proprioception
Sensations arising from the deep field (muscles and joints) as a result of the actions of the organism
Movement sense = awareness of joint movement
Position sense = awareness of static joint position
