Week 4 Flashcards
the shape of the muscle detemines function depending on:
- length
- number of fibres
- arrangement
state 2 facts about the length of muscle fibres:
- they shorten upt to 50% at resting length
- large range of motion = long muscle fibres
what does CSA mean in relatipon to number of muscle fribres?
cross sectional area measures the number of fibres
how does CSA effect tension?
- tension (force) is proportional to cross sectional area
- more fibres = greater CSA = greater tension
how does arrangement of fibres effect function?
- the way they are arranged means they can fit more fibres into the same space (which means more force) = more efficient.
what are parralllel fibres?
fibres arranged veritcally between tendons
what are prennate fibres?
fibre that are slanting diagonal so that more fibres fit
- reduced shortening but greater CSA
what are the anatomical levers and what do they do?
- bones - lever
- joints - pivot or fulcrum
- muscle contraction - pull
- load - external or internal (eg. lifting something or weight of skull)
in types of levers with muscle attachement _________ determines the function
lever arrangement
what are the 3 classes of levers?
first - stabilise joint position
eg. neck extentsion at the alanto - occipital joint
second - effective at overcoming loads
eg. plantarflexion at the ankle joint
third - long muscle, large range of movement + speed
eg. flexion at the elbow joint.
what are the 3 ttypes of muscle action?
concentric
eccentric
isometric
what are the qualities of concentric muscle action?
- muscle is active, develops tension
- change in joint position
- shortening of the muscle
(using/moving the muscle)
what are the qualities of eccentric muscle action?
- muscle is active, develops tension
- change in joint position
- lengthening of muscle
(controlled release)
what are the qualities of isometric muscle action?
- equal/stays the same/maintains
- muscle is active, develops tension
- NO change in joint position
- NO change in length of muscle
what are the 4 types of muscle roles?
agonist
antagonist
stabiliser
nuetraliser
what are the roles of agonists and antagonists?
agonists act concetrically (bicep shortens)
antagonists act eccentrically to counterbalance (triceps brachii lengthens to stop flexing too fast)
what is the role of stabilisers?
- when a muscle is active to hold a joint still (eg. holding book)
eg. biceps brachii role is a stabiliser and its action is isometric as there is n change in length.
what is the role of a nuetraliser?
- muscle eliminates an unwanted movement caused by another muscle.
eg. drinking from a glass - flexion yes, supination no, so pronator muscles nuetralise supinating effect of biceps brachii.
what are the rules of concentric muscle actions?
- the muscle that is anterior to the joint produces flexion
- the muscle posterior to the joint produces extension
- the muscle lateral to the joint produces abduction
- muscle medial to the joint produces adduction
* this applies to all joints except for the knee.
* * there is NO adduction muscles in HUBS 191 (other than ligaments) and only 1 abductor.
Tell me about the Deltoid (6)
- coming from clavicle + scapular
- attaches to lateral shaft of the humerous
- flexion (anterior fibres)
- abduction (lateral fibres)
- extension (posterior fibres)
- attaches to pectoral girdle
Tell me about the Biceps brachii (4)
- shoulder (flexion)
- elbow (flexion)
- radioulna joint (supination)
- attaches to the scapular and radius
Tell me about the Triceps brachii (3)
- shoulder (extension)
- elbow (extension)
- crosses over shoulder and elbow joints
Tell me about the Iliopsoas (3)
- hip (flexion)
- ilialus + psoas major insert/weave together to cross hip joint and insert in fermur
- anterior to hip
Tell me about Gluteus maximus (2)
- hip (extension)
- attachment to femur + large tendon