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37 Cards in this Set
- Front
- Back
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What are the roles of the muscles? |
-dynamic stability -joint protection -work in (in at least) pairs |
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the name of a muscle is determined by what features? |
-Shape-deltoid, rhomboid -size-gluteis maximus, teres minor -number of divisions-triceps brachii -direction of muscle fibers-external abdominal oblique -location-rectus femoris, palamris longus points of attachment-coracobrachialis, extensor -action-erector spinae, supinator, extensor digitorimini -any combination of the above |
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what is the effect of the muscle shape? |
-effects the ability to exert force -effects the range of motion to effectively produce force -cross sectional diameter (increase in diameter=increase in force) -muscle length (increase in length=increase in range of motion |
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how can muscles be arranged? |
-parallel -pennate |
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what is parallel muscle arrangement and what are the benefits from this arrangement? |
-arranged parallel to the length -produce larger range of motion |
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what is pennate muscle arrangement and what are the benefits from this arrangement? |
-shorter fibers -arranged obliquely -increased force production -uni and bi-pennate produce the strongest contractions |
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what are the properties of a muscle? |
-irritablity/excitability -contractility -extensibility -elasticity |
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define action of a muscle |
specific movement of the joint resulting from a concentric contraction that crosses a joint |
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define origin of a muscle |
proximal attachment of a muscle |
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define insertion of a muscle |
distal attachment |
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define intrinsic |
pertaining usually to muscles within or belonging solely to the body part on which they act. The small intrinsic muscles found entirely within the hand are examples |
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define extrinsic |
pertaining usually to muscles that arise or originate outside of (proximal to) the body part on which they act. The forearm muscles that attach proximally in the distal humerus and insert on the fingers are examples of extrinsic muscles of the hand |
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define innervation |
the nervous system responsible for providing stimuli |
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define lines of pull |
-helpful for understanding joint action -based on joint function -based on muscle location and organization |
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define amplitude |
the amplitude is the range of muscle fiber length between maximal and minimal lengthening |
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define gaster |
-belly or body -the central, fleshy portion of the muscle. This contractile portion of the muscle generally increases in diameter as the muscle contracts |
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what are muscle actions based on? |
the tension in the muscle |
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muscle actions______, ________, or __________ joint movement |
-cause -control -prevent |
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muscle actions can either be ________ or _______ |
isometric or isotonic |
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isometric |
-the joint angle remains constant "static" -preventing motion |
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isotonic |
change in joint angle "dynamic" |
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Isotonic contractions can either be______ or _______ |
-concentric: Causing motion -eccentric: controlling motion |
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concentric contractions |
-cause muscle shortening -overcome resistance -joint velocity and joint angle agree -+contraction |
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eccentric contractions |
-results in muscle lengthening -controls the descent of resistance -joint velocity and joint angle do NOT agree - -contractions |
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Agonist |
-causes joint motion through specified plane of motion when contracting concentrically -known as primary or prime movers if they contribute significantly more to the movement -the muscles most involved -can be assistant movers if they are less significant to the movement |
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Antagonist |
-located on opposite side of joint from agonist -known as contralateral muscles -cooperates with agonist by relaxing and allowing movement -perform opposite joint motion of agonist
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Stabilizer |
-surround joint or body part -contract to fixate or stabilize the area to enable another limb or segment to move -known as fixators -essential in establishing a relatively firm base for the more distal joints to work from |
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synergists |
-assist in the action of agonists -not necessarily prime movers for action -known as guiding muscles -assist in refined movement -rule out undesired motions -there are helping synergists and true synergists |
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describe a helping synergist |
-have action in common but also actions antagonistic to each other -help another muscle move the joint in the desired manner while simultaneously preventing undesired actions |
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describe a true synergist |
-contract to prevent an undesired joint action of agonist -no direct effect on agonist action |
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neutralizers |
-counteract or neutralize the action of another muscle to prevent undesirable movements such as inappropriate muscle substitutions -referred to as neutralizing -contract to resist specific actions of other muscles |
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force couple |
-two or more forces are pulling in different directions on an object, causing the object to rotate about its axis -can result in more efficient movement |
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what does it mean if a muscle has multiple agonist actions? |
-attempt to perform all of their actions when contracting -cannot determine which actions are appropriate for the task |
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actions performed by a muscle depends upon what factors? |
-motor units activated -joint position at time of contraction -planes of motion allowed int he joint -axis of rotation possible in the joint -muscle length -relative contraction or relaxation of other muscles acting on the joint |
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two muscles may work in synergy by counteracting.... |
their opposing actions to accomplish a common action |
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explain reversal of a muscle function |
a muscle group described to perform a given function can contract to control the exact opposite motion |
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how can you determine muscle action? |
-consideration of anatomical lines of pull -anatomical dissection -palpation -models -electromyography -electrical stimulation |
