Flashcards in MSK S2 Deck (37)
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What are the muscle groups?
Agonists
Antagonists
Synergists
Fixators
1
What is the function of agonists?
The main muscles responsible for a particular movement
2
What is the function of antagonists?
Oppose agonists
3
What is the function of synergists?
Assist agonists (neutralise extra movement)
4
What is the function of fixators
Stabilises action of agonist (eg by fixing non moving joint whilst agonist acts over two joints)
5
What are the types of muscle contraction?
Isotonic contraction
Isometric contraction
6
What are the types of isotonic contraction?
Concentric
Eccentric
7
Define isotonic contraction
Constant tension but variable length - the muscle changes length and moves the load
8
Define isometric contraction and give an example
Constant length but variable tension eg hand grip
9
Describe concentric contraction and give an example
Muscle shortens eg lifting a load with the arm
10
Describe eccentric contraction and give an example
The muscle exerts a force whilst being extended eg walking down a hill.
This type of muscle action can cause delayed onset muscle soreness
11
What are the muscle fibre types?
I Slow twitch
IIa Fast twitch
IIb Fast twitch
12
What is spatial summation in relation to muscle?
The more neurones which stimulate the muscle, the more fibres will be activated so the greater the overall force of the contraction.
13
What is temporal summation in relation to muscle?
The more action potentials that arrive at a muscle per second, the greater the force of the contraction.
14
What is tetanic contraction?
When the muscle is at it's maximal contraction.
In the disease tetanus, this is caused by the toxin secreted by Clostridium tetani.
15
What is an EMG?
An electromyography
Electrodes may be placed above or in muscles to measure activity
Can be used to diagnose eg MND (motor neurone disease)
16
What is a marker for muscle damage?
Serum creatine kinase
17
Define 'contracture'
A state of constant contraction caused by ATP depletion
Myosin heads are unable to detach from actin filaments
Seen in rigor mortis
18
What components make up the axilla?
Axillary artery
Axillary vein
Lymphatic vessels
Axillary lymph nodes
Axillary fat
Brachial plexus
19
How are the sections of the Axillary artery and Axillary vein numbered?
In the direction of blood flow, ie in the artery, the 1st part is closest to the heart and the 3rd is furthest.
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Describe the first part of the Axillary artery
In the Axillary sheath
Has one branch - the superior thoracic artery
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Describe the second part of the Axillary artery
Posterior to pectoralis minor
Two branches: lateral thoracic artery and thoracocromial artery
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Describe the third part of the Axillary artery
Runs from pectoralis minor to teres major
Three branches: subscapular artery, and posterior and anterior circumflex humeral arteries
23
Describe the Axillary vein
On the anteromedial side of the Axillary artery
Formed by the union of the brachial and basilic veins at the inferior border of teres major
Very variable between individuals
Is a collateral route of venous return in case of vena cava obstruction
24
From which vertebrae do the roots of the brachial plexus originate?
C5, C6, C7, C8, T1
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What are the parts of the brachial plexus?
Roots
Trunk
Divisions
Cords
Branches
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What nerves branch off the roots of the brachial plexus and where do they originate?
The C5, C6 & C7 roots all have a branch which goes on to form the long thoracic nerve
The C5 root also branches to form the dorsal scapular nerve and to contribute to the phrenic nerve
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How do the roots of the brachial plexus form trunks?
The C5 and C6 roots merge to form the superior trunk
The C7 root forms the middle trunk
The C8 and T1 roots merge to form the inferior trunk
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What nerves branch off the superior trunk of the brachial plexus?
Suprascapular nerve and the nerve to the subclavius
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