MSK S2

Question 0

What is the function of agonists?

Answer 0

The main muscles responsible for a particular movement

Question 1

What are the muscle groups?

Answer 1

Agonists
Antagonists
Synergists
Fixators

Question 2

What is the function of antagonists?

Answer 2

Oppose agonists

Question 3

What is the function of synergists?

Answer 3

Assist agonists (neutralise extra movement)

Question 4

What is the function of fixators

Answer 4

Stabilises action of agonist (eg by fixing non moving joint whilst agonist acts over two joints)

Question 5

What are the types of muscle contraction?

Answer 5

Isotonic contraction

Isometric contraction

Question 6

What are the types of isotonic contraction?

Answer 6

Concentric

Eccentric

Question 7

Define isotonic contraction

Answer 7

Constant tension but variable length - the muscle changes length and moves the load

Question 8

Define isometric contraction and give an example

Answer 8

Constant length but variable tension eg hand grip

Question 9

Describe concentric contraction and give an example

Answer 9

Muscle shortens eg lifting a load with the arm

Question 10

Describe eccentric contraction and give an example

Answer 10

The muscle exerts a force whilst being extended eg walking down a hill.
This type of muscle action can cause delayed onset muscle soreness

Question 11

What are the muscle fibre types?

Answer 11

I Slow twitch
IIa Fast twitch
IIb Fast twitch

Question 12

What is spatial summation in relation to muscle?

Answer 12

The more neurones which stimulate the muscle, the more fibres will be activated so the greater the overall force of the contraction.

Question 13

What is temporal summation in relation to muscle?

Answer 13

The more action potentials that arrive at a muscle per second, the greater the force of the contraction.

Question 14

What is tetanic contraction?

Answer 14

When the muscle is at it’s maximal contraction.

In the disease tetanus, this is caused by the toxin secreted by Clostridium tetani.

Question 15

What is an EMG?

Answer 15

An electromyography
Electrodes may be placed above or in muscles to measure activity
Can be used to diagnose eg MND (motor neurone disease)

Question 16

What is a marker for muscle damage?

Answer 16

Serum creatine kinase

Question 17

Define ‘contracture’

Answer 17

A state of constant contraction caused by ATP depletion
Myosin heads are unable to detach from actin filaments
Seen in rigor mortis

Question 18

What components make up the axilla?

Answer 18

Axillary artery
Axillary vein
Lymphatic vessels
Axillary lymph nodes
Axillary fat
Brachial plexus

Question 19

How are the sections of the Axillary artery and Axillary vein numbered?

Answer 19

In the direction of blood flow, ie in the artery, the 1st part is closest to the heart and the 3rd is furthest.

Question 20

Describe the first part of the Axillary artery

Answer 20

In the Axillary sheath

Has one branch - the superior thoracic artery

Question 21

Describe the second part of the Axillary artery

Answer 21

Posterior to pectoralis minor

Two branches: lateral thoracic artery and thoracocromial artery

Question 22

Describe the third part of the Axillary artery

Answer 22

Runs from pectoralis minor to teres major

Three branches: subscapular artery, and posterior and anterior circumflex humeral arteries

Question 23

Describe the Axillary vein

Answer 23

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

Question 24

From which vertebrae do the roots of the brachial plexus originate?

Answer 24

C5, C6, C7, C8, T1

Question 25

What are the parts of the brachial plexus?

Answer 25

``` Roots Trunk Divisions Cords Branches ```

Question 26

What nerves branch off the roots of the brachial plexus and where do they originate?

Answer 26

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

Question 27

How do the roots of the brachial plexus form trunks?

Answer 27

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

Question 28

What nerves branch off the superior trunk of the brachial plexus?

Answer 28

Suprascapular nerve and the nerve to the subclavius

Question 29

How do the trunks of the brachial plexus divide?

Answer 29

The superior, middle and inferior trunks all branch into posterior and anterior. The anterior branches of the superior and middle trunks join to form the lateral cord The posterior branches of the superior, middle and inferior trunks join to form the posterior cord The anterior branch of the inferior trunk becomes the medial cord

Question 30

How is the lateral cord formed?

Answer 30

The anterior branches of the superior and middle trunks join to form the lateral cord

Question 31

What nerve(s) originate(s) from the lateral cord?

Answer 31

The lateral pectoral nerve

Question 32

How is the posterior cord formed?

Answer 32

The posterior branches of the superior, middle and inferior trunks join to form the posterior cord

Question 33

What nerve(s) originate(s) from the posterior cord?

Answer 33

AXILLARY NERVE Thoracodorsal nerve Inferior subscapular nerve Superior subscapular nerve

Question 34

How is the medial cord of the brachial plexus formed?

Answer 34

The anterior branch of the inferior trunk becomes the medial cord

Question 35

What nerve(s) originate(s) from the medial cord?

Answer 35

Medial pectoral nerve Medial cutaneous nerve of arm Medial cutaneous nerve of forearm

Question 36

How do the cords of the brachial plexus become the terminal nerves?

Answer 36

The lateral and medial cords split. A branch of each join together to form the median nerve The other branch of the lateral cord forms the musculocutaneous nerve The other branch of the medial cord forms the ulnar nerve The posterior cord becomes the radial nerve