MSK Session 2 Flashcards
(117 cards)
0
Q
What type of muscle is the diaphragm?
A
Skeletal
1
Q
What two types of muscle are there?
A
Striated
Non-striated
2
Q
Give an example of each type of skeletal muscle arrangement.
A
Circular: orbicularis oris Convergent: pec. major Parallel: sartorius Unipennate: extensor digitorum longus Multipennate: deltoid Fusiform: biceps brachii Bipennate: rectus femoris
3
Q
How are skeletal muscles attached to bones?
A
By tendons
4
Q
What does skeletal muscle continually contract?
A
To maintain posture
5
Q
What is the mechanical efficiency of skeletal muscle?
A
~20%, rest dissipated as heat
6
Q
What is the gross anatomy of skeletal muscle?
A
Epimysium –> perimysium –> endomysium
Muscle –> fascicle –> muscle fibre
7
Q
What is fasciculation?
A
Low level muscle twitch often seen in the face when tired/nervous or more severely in motor neurone disease
8
Q
What is a first class lever?
A
Where the force and load are on opposite sides of the fulcrum like a see-saw e.g. neck
9
Q
What is a second class lever?
A
Where the force and load are to the left of the fulcrum like a wheelbarrow e.g. in the foot where the ball is the fulcrum
10
Q
What is a third class lever?
A
Most common type of lever where the force and load are to the right of the fulcrum, like a fishing rod
11
Q
What can be said about the length along which force acts in a third class lever?
A
Large
12
Q
What are agonists?
A
Prime movers
13
Q
What are antagonists?
A
Oppose prime movers
14
Q
What act together to allow fine, smooth movement?
A
Agonists and antagonists
15
Q
What are synergists?
A
Muscles that assist prime movers by neutralising extra motion to keep motion in one direction
16
Q
What are fixators?
A
Muscles that stabilise the action of prime movers by fixing non-moving joints when prime mover is acting over two joints
17
Q
What are compartments?
A
Groups of muscles surrounded by connective tissue
18
Q
What is compartment syndrome?
A
When pressure builds up inside a compartment due to the inability of the surrounding CT to undergo rapid expansion and causes nerve compression
19
Q
What can cause compartment syndrome?
A
Bleeding
20
Q
What effect can long-term training have on the connective tissue surrounding a compartment?
A
Expansion
21
Q
What is isotonic muscle contraction?
A
Constant tension with variable muscle length that changes to move a load
22
Q
What happens in concentric isotonic muscle contraction?
A
Muscle shortens
23
Q
What happens in eccentric isotonic muscle contraction?
A
Muscle exerts force whilst extended e.g. walking downhill
24
What is isometric muscle contraction?
Muscle remains a constant length but has variable tension
25
Describe isometric contraction in hand grip.
Forearm muscles do not change length but exert force
| Small muscles also used which rapidly increase BP - risky for elderly and hypertensive
26
What are the three types of muscle fibre?
Type I - slow oxidative
Type IIa - fast oxidative
Type IIb - fast glycolytic
27
What is used to identify muscle type?
Mitochondrial staining on post mortem/needle biopsy sample
28
What characterises slow oxidative muscle?
```
Aerobic
High myoglobin levels
Red colour
Lots of mitochondria
Rich capillary supply
Fatigue resistant - used in endurance activities and posture
```
29
What characterises fast oxidative muscle?
```
Aerobic
High myoglobin levels
Red to pink colour
Many mitochondria
Rich capillary supply
Moderate fatigue resistance - used for walking and sprinting
```
30
What characterises type IIb muscle?
```
Anaerobic glycolysis
Low myoglobin levels
White (pale) colour
Few mitochondria
Poorer capillary supply
Rapidly fatiguable - used for short intense movement
```
31
What is proprioception?
Awareness of self
32
How do specialised muscle fibres in the belly of a muscle allow proprioception to take place?
Sense stretch and send signals back to brain reporting tension and strain levels in the muscle
33
What can be considered as the feedback control of movement as well as feedback from the joints?
Proprioception
34
What is a motor unit?
Motor neurone and the muscle fibre it innervates
35
Where is the output of a motor neurone?
Through ventral root
36
How does the number of muscle fibres controlled by a motor neurone vary with control?
More control = fewer fibres innervated by a single neurone
37
What is cross talk?
Method of communication b/w neurones and muscle using signalling molecules
38
How does atrophy of a neurone or a muscle cause atrophy of its corresponding component?
Signals are either not released or not needed
39
Which signalling molecule maintains communication b/w motor neurone and muscle and is very important in the NMJ?
Neutrophin-3
40
What causes baseline muscle tone in muscles at rest?
Motor neurone activity
| Muscle elasticity due to protein content
41
What controls baseline muscle tone?
Motor control centres in the brain
| Afferent fibre signals originating from the muscle
42
What is hypotonia?
Low level of muscle tone
43
What can cause hypotonia?
Primary degradation of the muscle
Lesions of cerebellum and cerebral/shock causing damage to motor cortex involved in feedback mechanism
Lesion of sensory afferents from the muscle spindles
Lesions of lower motor neurones e.g. polyneuritis
Spinal neural shock
44
What does polyneuritis affect?
Multiple motor neurones in body in different places
45
How is ACh exocytosed from the NMJ?
AP sweeps around membrane --> opens calcium channels --> calcium in
46
What happens when 2 ACh bind to the alpha-subunit of nicotinic receptors on the effector muscle?
Conformational change of ligand gated sodium --> sodium in --> depolarisation --> calcium release from SR
47
Why are anaesthetics used?
Less tissue damage is caused if the tissue is relaxed
48
What is given in addition to anaesthetics to counteract the initial contraction they cause by inhibiting AChE?
Neuromuscular block
49
What is spatial summation?
Type of recruitment learned throughout life
50
How does spatial summation work?
More motor neurones are activated so more muscle fibres are recruited to develop more force
51
Where do reflex pathways in spatial summation come from?
Muscle spindles
Joint receptors
Golgi tendon organs of muscle fibres
52
What do Golgi tendon organs sense?
Changes in muscle tension
53
What is temporal summation?
Recruitment where increased frequency of AP to muscle fibres causes summation
54
What is the difference between fused and infused tetanus?
```
Unfused = twitch
Fused = continuous force = no relaxation
```
55
What is present in all soil that interferes with feedback control of muscle tension to cause continual contraction?
Clostridium tetani
56
What is electromyography?
Electrodes placed above/in muscles to record their electrical activity
57
Why is the amplitude in an electromyography equivalent to the force of contraction?
Increased recruitment of motor units
58
What is seen in an EMG that indicates MND?
Graph doesn't match up
59
How is relaxation of a muscle achieved by lower cytoplasm calcium content?
Pumping calcium back into SR via calcium pumps
| Binding to calmodulin
60
What are sources of energy for muscle contraction?
Short term ATP stores in muscle fibre
Creatine phosphate
Aerobic and anaerobic glycolysis
Oxidative phosphorylation
61
What energy source for muscle contraction can be measured for suspected muscle damage?
Creatine phosphate
62
How does anaerobic glycolysis cause muscle cramp?
Conversion by LDH of pyruvate to lactate which acts on nerve endings coupled with a decrease in pH
63
When does peripheral fatigue occur?
Muscle glycogen stores are depleted
| Within one minute of blood flow interruption
64
What is contracture?
State of continuous contraction when ATP is depleted
65
What causes rigor mortis?
Myosin X-bridges unable to detach from actin filaments
66
What is the time frame of rigor mortis?
Slow onset, peaks at 12-13 hours and can give v. exact time of death
67
What forms the anterior border of the axilla?
Pec. minor and major
68
What makes up the medial border of the axilla?
Serratus anterior
| Thoracic wall
69
What forms the posterior border of the axilla?
Scapularis
Teres major
Latissimus dorsi
70
What forms the lateral border of the axilla?
Intertubecular sulcus
71
What forms the apex of the axilla?
Cervico-axillary canal bounded by the first rib, clavicle and superior edge of scapula a
72
What transverses the apex of the axilla?
Arteries
Veins
Lympahtics
Nerves
73
What forms the base of the axilla?
Concave skin
Subcutaneous tissue
Axillary fascia from 4th rib to axillary fossa
74
What enters and leaves the clavipectoral triangle?
Cephalic vein enters
| Medial and lateral pectoral nerves leave
75
What is found in the quadrangular space?
Post-circumflex humeral artery
| Axillary nerve
76
What is the main artery supplying the upper limb?
Axillary artery
77
What are the parts of the axillary artery?
Medial, posterior and lateral to pec. minor
78
Describe the path of the axillary artery.
Lateral border of 1st rib --> medial border of pec. minor --> lateral border of pec. minor --> inferior border of teres major
79
What arteries branch off from the axillary artery?
```
Super thoracic
Thoraco-acromial
Lateral thoracic
Subscapula artery
Anterior and posterior circumflex humeral arteries
```
80
What is the collateral route enabling venous return if IVC is obstructed?
Thoraco-epigastric veins
81
Brachial and basilic vein --> subclavian vein --> second part of axillary vein --> initial distal end
Describe the path of the axillary vein.
82
Which veins drain into the axillary vein?
Thoraco-epigastric
Cephalic
Corresponding veins to the thoraco-acromial artery
83
Moving anteriorly to posteriorly in the axilla, how are the artery, nerve and vein arranged?
Vein
Artery
Nerve
(VAN)
84
What 5 groups of lymph nodes are present in the axilla?
```
Pectoral
Subscapular
Humeral
Central
Apical
```
85
Where are the pectoral lymph nodes found and what area do they drain?
3-5 nodes on medial wall
| Breast
86
Where are the subscapular lymph nodes located and what do they drain?
6-7 nodes on posterior axillary fold
| Posterior wall and scapula
87
Where are the humeral lymph nodes found and what do they drain?
4-6 nodes on lateral wall
| UL
88
Where are central and apical lymph nodes found?
```
Central = 3-4 nodes deep to pec. minor
Apical = all other groups and lympahtics not already classified
```
89
What are the components of the brachial plexus?
```
Roots
Trunks
Divisions
Cords
Terminal branches
```
90
Where do the roots of the brachial plexus arise?
Paired spinal nerves that leave the spinal cord via the intervertebral foramen of the vertebral column which divide into an anterior part
91
What is the fate of the posterior division of the spinal nerves that have left the spinal cord?
Innervate skin and musculature of the trunk
92
What do the roots of the brachial plexus pass between to enter the base of the neck?
Anterior and medial scalene muscles
93
What happens in the brachial plexus at the base of the neck?
Roots converge to form three trunks
94
What path do the trunks of the brachial plexus take?
Move laterally crossing the posterior triangle of the neck
95
What happens to the brachial plexus within the posterior triangle of the neck?
Each trunk divides into anterior and posterior branches
96
What path do the divisions of the brachial plexus take?
Pass into the axilla
97
What happens to the brachial plexus in the axilla?
Divisions combine to form three nerves which are the cross of the brachial plexus
98
What are the cords of the brachial plexus named relative to?
Axillary artery
99
What do the cords of the brachial plexus give rise to?
Major branches
100
What happens to the brachial plexus in the axilla and proximal part of the UL?
3 cords become 5 branches
101
What is the function of the five major branches of the brachial plexus?
Provide innervation to the muscle and skin they pass over
102
What are the five major branches of the brachial plexus?
```
Ulnar nerve
Radial nerve
Median nerve
Axillary nerve
Musculocutaneous nerve
```
103
What are the nerve roots of the ulnar nerve?
C8 and T1
104
What are the nerve roots of the radial nerve?
C5-8 and T1
105
What are the nerve roots of the median nerve?
C6-8 and T1
106
What are the nerve roots of the axillary nerve?
C5 and 6
107
What are the nerve roots of the musculocutaneous nerve?
C5-7
108
What does the ulnar nerve innervate?
Muscles of hand
Flexor carpi ulnaris
Medial half of flexor digitorum profundus
Sense in anterior and posterior medial 1.5 fingers and palm area
109
What does the radial nerve innervate?
Triceps brachii
Extensor muscles in posterior compartment of forearm
Sense in posterior aspect of arm and forearm
Sense in posterior and lateral aspect of hand
110
What does the median nerve innervate?
Flexor muscles in forearm
Thenar muscles
2 lateral lumbricals that move index and middle fingers
Sense in lateral palm and lateral 3.5 fingers on palmar surface of hand
111
What branches does the median nerve give rise to?
Palmar cutaneous branch
| Digital cutaneous branch
112
What does the axillary nerve innervate?
Deltoid
Teres major
Long head of biceps brachii
Sense in regimental badge area
113
What branch does the axillary nerve give rise to?
Superior lateral cutaneous nerve of arm
114
What does the musculocutaneous nerve innervate?
Brachialis
Biceps brachii
Corachobrachialis
Sense in lateral half of anterior forearm and small lateral portion of posterior forearm
115
What branch does the musculocutaneous nerve give rise to?
Lateral cutaneous branch of forearm
116
What shape do the musculocutaneous, median and ulnar nerve form in the brachial plexus?
M
