Mod 4 Musculoskeletal system 3

Question 1

What influences force?

Answer 1

skeletal muscle contraction influence force

Question 2

How to produce force?

Answer 2

Produces force to power movement (converts ATP into mechanical energy)

Question 3

What are the three types of muscle tissue?

Answer 3

1) skeletal
2) cardiac
3) smooth

Question 4

What are the functions of the skeletal muscle

Answer 4

1) Produce movement: responsible for locomotion and balance
2) maintain posture and body position
3) stabilize joints
4) generate heat (contract) (maintain body temp)

Question 5

The ORDER

Answer 5

Muscle –> fascicle –> fiber –> myfibrils –>sacromeres –> basic contractile unit of skeletal muscles

Question 6

What do muscles recieve?

Answer 6

a nerve, artery and vein

Question 7

What are the three levels of muscle tissue?

Answer 7

1) Epimysium, 2) Perimysium 3) Endomysium

Question 8

Epimysium?

Answer 8

dense irregular, the connective tissue surrounding the entire muscle, may blend with fascia

Question 9

Perimysium?

Answer 9

Fibrous dense connective tissue surrounding fascicles (groups of muscle fibers)

Question 10

Endomysium?

Answer 10

Fine areolar connective tissue surrounding each fibre

Question 11

How do muscles attach to the skeleton?

Answer 11

Muscles span joints (attach to bones at least 2 places, but origin and insertion, they can be direct and indirect

Question 12

Origin?

Answer 12

The attachment that is relatively fixed (typically proximal)

Question 13

Insertion?

Answer 13

The attachment that is more moveable, usually distal

Question 14

Direct attachment?

Answer 14

Fleshy: epimysium fused to the periosteum of bone or perichondrium of cartilage

Question 15

Indirect attachment?

Answer 15

Indirect: connective tissue wrapping extend beyond muscle as rope-like tendon/sheet-like aponeurosis

Question 16

Tendon?

Answer 16

Tendons are rope-like bands of connective tissue

Question 17

What makes up a muscle?

Answer 17

Together a muscle and its tendon made up a muscle-tendon pair

Question 18

What can muscles do?

Answer 18

Muscles can only pull on tendons or skeletal (never push)

Question 19

What are the muscle action, functional groups?

Answer 19

1) Agonist
2) Antagonist
3) Synergist
(antagonist and agonist are located on the opposite sides of joint)

The muscle that is contracting is called the agonist and the muscle that is relaxing or lengthening is called the antagonist. One way to remember which muscle is the agonist – it’s the one that’s in ‘agony’ when you are doing the movement as it is the one that is doing all the work.

Question 20

What is individual muscle force influenced by?

Answer 20

Influenced by muscle architecture and function

Question 21

What are the different types of muscle arrangements (architecture)

Answer 21

1) parallel 2) Pennate 3)circular

Question 22

What is meant by parallel?

Answer 22

Fascicles lie in parallel to muscles line of action: strap and fusiform
- long muscle fascicles mean more muscle shortening =larger ROM at joint (lower PCSA)

Question 23

What is meant by pennate?

Answer 23

Fascicles at an angle relative to the line of action
- uni-pennate
- bi- pennate
- multi-pennate
(PICTURE)
Short angle fibres (smaller ROM)
- more fibre packed within a given volume = higher forces are more power (higher PCSA)

Question 24

What is the muscle’s physiological cross-sectional area?

Answer 24

Different muscles have different force- muscle physiological cross-sectional area

Question 25

What is the greatest predictor of force?

Answer 25

The greatest predictor of force is the muscle's physiological cross-sectional area ( the cross-sectional area of the muscle is perpendicular to its fiber direction)

Question 26

PCSA?

Answer 26

muscle volume/fiber length

Question 27

How does sarcomere length influence force?

Answer 27

some overlap or actin and myosin in 'relaxed muscle', the greater the overlap in actin and myosin with active and passive shortening of the muscle -- the more possible actin and myosin cross-bridges available Influences the amount of force that can be developed, length-tension and force-length relationship

Question 28

What makes up the muscle-tendon unit and why are these components important when considering muscle force?

Answer 28

- Contractile component (CC)- muscle fibers actin, myosin cross-bridges - series elastic component (SEC) intracellular titin, tendon - parallel elastic component (PEC) connective tissue (epimysium), perimysium, endomysium, passive cross-bridge connections

Question 29

Passive force?

Answer 29

parallel elastic component (PEC) connective tissue within the muscle- epimysium, perimysium and endomysium

Question 30

Why is connective tissue important?

Answer 30

it is important for generation of passive force and limits overstretch

Question 31

What is the motor unit?

Answer 31

A single motor unit is the smallest functional unit in the musculoskeletal system, 1 motor unit= 1 motor neuron, its motor axon and all of the muscle fibers it innervates

Question 32

Degree of excitatory influences recruitment

Answer 32

lots of excitatory input in a motor neuron= many motor neurons being recruited

Question 33

What is force influenced by?

Answer 33

Force is influenced by the discharge rate of active motor units and the fibre type of the motor units

Question 34

what are slow types of fibres?

Answer 34

Oxidative fibres rely on aerobic respiration, oxygen is the energy source Slow type 1 fibres: cinderella fibres (long and fatigue), the high proportion in postural muscle, smaller force magnitude and longer force duration.

Question 35

Glycolytic fibers?

Answer 35

use glycolysis for energy source, break down of glucose into ATP

Question 36

Types glycolytic fibres?

Answer 36

Fast-twitch, type 2B fibers, larger force, shorter duration, and faster fatigue

Question 37

What are the intermediate fibers?

Answer 37

Intermediate fibers use oxygen as an energy source (ATP), uses aerobic respiration, use many mitochondria and have high myoglobin

Question 38

Types of intermediate fibers?

Answer 38

Fast-twitch type 2A fibers, a larger force than type 1, fatigue faster than type 1

Question 39

Order of fibers?

Answer 39

slow-twitch, low force, fatigue resistant, intermediate, fast-twitch, more force, fatigues more quickly

Question 40

What is Henneman's size principle

Answer 40

the smaller the units are usually recruited first, the larger units are recruited later

Question 41

Types of contraction?

Answer 41

Static --> isometric (same length) and dynamic - concentric (shortening) movement up - eccentric (lengthening) movement down

Question 42

Notes

Answer 42

the maximum force that can be produced is dependent on the direction such that eccentric is > isometric >concentric

Question 43

Why does the contraction type matter?

Answer 43

- the absolute force produced depends on the motor task - an eccentrically contracting muscle can produce more force at the same muscle length than a concentrically muscle * * you can hold more load than you can lift, and the lower more load, than you can hold steady

Question 44

What is a parallel fascicle length?

Answer 44

Where fibers are parallel to the force-generating axis

Question 45

What is a uni-pennate fascicle length?

Answer 45

Where fibers at an angle to the force-generating axis

Question 46

What is a multi-pennate fascicle length

Answer 46

where fibers are at multiple angles to the force-generating axis