003 Muscles and movement Flashcards
1
Q
what 2 systems is the musculoskeletal system made out of?
A
- skeletal system
- muscular system
2
Q
what is the role/function of the skeletal system?
A
- bones, cartilages, joints
- protection, support
- body movement
- produces blood cells
- stores minerals and fats
3
Q
what is the role/function of the muscular system?
A
- muscles attached to the skeletal system
- maintains posture and balance
- produces body movement
- generates body heat
4
Q
in basic terms, how do we move?
A
- muscles pull on bones
- joints between bones allow either no movement, little movement or free movement
5
Q
what are the 3 different types of joints?
A
- fibrous
- cartilaginous
- synovial
6
Q
describe fibrous joints and give an example
A
- bones linked by fibrous connective tissue
- little or no movement
- e.g. sutures in cranium of skull
7
Q
describe cartilaginous joints and give an example
A
- bones linked by hyaline cartilage or fibrocartilage
- elasticity allows some movementy
- e.g. pubic symphysis, intervertebral discs
8
Q
describe synovial joints and give an example
A
- joints enclosed by a fluid filled synovial capsule
- allows a lot of movement
- e.g. knee joint
9
Q
what are the 6 different types of synovial joints?
A
- plane joint
- saddle joint
- hinge joint
- pivot joint
- ball and socket joint
- ellipsoid joint
10
Q
what is a plane joint and give an example
A
- very slight movement
- e.g. intervertebral
11
Q
what is a saddle joint and give an example
A
- 2 axis movement
- e.g. carpometacarpal pollicis (thumb joint)
12
Q
what is a hinge joint and give an example
A
- 1 axis movement
- e.g. elbow
13
Q
what is pivot joint and give an example
A
- rotational movement
- e.g. proximal radioulnar in elbow
14
Q
what is ball and socket joint and give an example
A
- multiple axis movement and some rotational movement
- e.g. shoulder joint
15
Q
what is ellipsoid joint and give an example
A
- 2 axes movement, but can be also 1 axis ( metacarpophalangeal) or multiple axes (radiocarpal) movement
- e.g. atlantooccipital joint between spine and skull
16
Q
what is extension in the elbow, shoulder, neck, trunk, knee and foot?
A
- elbow = opening/increasing the joint angle = arm straight
- shoulder = moving arm posterior to coronal plane
- neck = moving neck backwards, posterior to coronal plane
- trunk = moving body backwards
- knee = increasing joining angle = leg straight
- foot = both directions are flexion, pointing down = plantar flexion, pointing towards shin = dorsiflexion
17
Q
what is abduction?
A
- move away from the midline
- e.g. raise arms up and out
18
Q
what is adduction?
A
- move towards the midline/bring together
- e.g. bring arms down by torso sides
19
Q
what is lateral rotation?
A
rotating the limb away from the midline from the joint/bend
- e.g. rotating the forearm away from the trunk at the elbow
20
Q
what is medial rotation?
A
- rotating the limb towards the midline from the joint/bend
- e.g. rotating the forearm towards the trunk at the elbow
21
Q
what is pronation?
A
- lying face down
- rotating palm until face down
- ulna and radius are crossed
22
Q
what is supination?
A
- facing upwards
- rotating palm until facing up
- ulna and radius are uncrossed
23
Q
what is Dysdiadochokinesia?
A
- when you cannot rapidly change between pronation and supination due to cerebellum injury
24
Q
what is circumduction?
A
- a combination of flexion, extension, abduction and adduction
- shoulder movements
- imagine moving arm in the shape of a cone
25
what is the relationship with muscle length when contracting?
- when muscles are activated they contract, but they do not always shorten
- muscle length depends on the level of activation and load on it
- muscles always generate a force but it may be isotonic or isometric contractions
e.g. lifting a table stuck to the ground - cant lift, muscles contracting but not shortening
26
what is an isotonic contraction?
- (same force)
- the force/tension generated by the muscle is greater than the load, so the muscle shortens
- the load is lifted against gravity
27
what is an isometric contraction?
- ( same length)
- the force/tension generated y the muscle is less that the load so it cannot shorten
- the load is not raised against gravity
( the muscle may 'shorten' due to elasticity of tendons )
28
what is the structure of muscle?
actin and myosin filaments --> sarcomeres --> myofibrils --> muscle fibre/cells --> fascicles --> muscle
29
what is the mechanism of how actin and myosin cause contractions called?
- sliding filament mechanism/cross-bridge formation
30
briefly describe the sliding filament mechanism/cross-bridge formation
- myosin thick filaments grabbing onto actin thin filaments and sliding them over the myosin filaments to bring them together, shorten the sarcomere and contract the muscle
31
how are muscles activated?
- motor neurons of the spinal cord or brainstem receive an electrical impulse from glutamate neurotransmitter which then transmits a signal to the muscle with acetlycholine neurotransmitter to the muscle
- each motor neurone controls more than one muscle fibre via neuromuscular junctions
32
what is a motor unit?
- motorneurone and its associated muscle fibres
33
what is the relationship with the size of the motor neuron and the size of force/tension produced?
- the larger the motor unit, the larger the force/tension produced
34
how can a higher force be generated from a motor unit?
- by increasing the rate of firing motorneurons
35
what is the relationship between sarcomere length and muscle tension?
- the optimal overlap of actin and myosin is 2-2.05 distance betweenthe z lines
- the greater the actin and myosin overlap, the greater the contraction = greater force/tension, until it reaches its optimum, after when actin and myosin overlap too much there can be no contraction = little or no force
- think about flexing wrist and trying to grab something, if you overstretch/over contract a muscle, less force is produced
- so despite motor commands, the muscle may not have as much force depending on muscle length and velocity of shortening
36
what pairing are muscles normally aranged into?
- agonist and antagonist = opposite actions
- e.g. bicep and tricep
37
how does the motor system deal with non-linearities with the muscle (e.g. muscle length)?
- feedback (proprioception)
38
what is proprioception?
- feedback from the muscles for the motor control system
- length and tension information is proprioception (self sensation)
- information from the muscle is detected in the muscle and sent to the nervous system to alter the motor neuron firing
39
what 2 features in muscles contribute to proprioception?
- muscle spindle = specialised muscle cells which detect muscle stretch and shortening
- golgi tendon organ = detects change in muscle tension
40
You are walking across a flat floor and then begin to ascend a staircase. What class or
classes (postural/voluntary etc) of movement control are likely to be involved.
This set of actions will involve all of the types of movement control. (i) The stepping
part of walking is rhythmic and there will be (ii) postural components associated with
the stepping action. The staircase will be detected with vision, in most cases, and (iii)
voluntary movements will superimpose on the rhythmic actions walking to direct the
stepping to the first staircase step and fit the stepping pattern to the size of the stairs.
Raising the body for each step will require (iv) balance control to avoid pitching forward
or toppling backwards
41
What are the essential features of a synovial joint?
The joint is enclosed in a fluid-filled capsule
42
Define a flexion of the elbow joint
A movement that reduces the angle of the joint
43
Define an extension movement of the trunk
A movement of the trunk towards the space posterior to the mid-coronal plane
44
In muscle action, are there differences between contraction and shortening?
Yes, important differences. Contraction is the development of tension by the muscle in
response to its activation. Shortening is the result of muscle contraction if the tension is
greater than the load.
45
Define the motor unit
The motor unit is the motoneuron, its axon and all of the muscle fibres that it
innervates (controls). When a motoneuron signals to the muscle fibres it innervates, all
of those fibres will be activated. This motoneuron cannot activate more or fewer than
the fibres it contacts.
46
Which is the agonist muscle and which is the antagonist muscle for elbow extension?
Agonist – triceps; antagonist – biceps
47
Name two proprioceptors and define which properties of muscle contraction they
detect.
The muscle spindle detects length changes, stretch. It increases its firing rate to stretch
(lengthening).
The Golgi Tendon Organ detects tension in the muscle. Tension is a force. GTO firing rate
increases with increases in tension.
