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44 Cards in this Set
- Front
- Back
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Functions of Muscle Tissue
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-stabilize posture -assist circulation (thermogenesis) |
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Muscle Insertion |
-inserts at the more movable bone -tend to be closer to the distal end |
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Muscle Origin |
-originates at the more stable bone -tend to be closer to the trunk |
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Reversal of Muscle Action |
-instead of the insertion moving toward the origin, the origin moves toward the insertion -the proximal bone, which is usually more stable, has become more movable |
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Muscle Names |
-location (tibialis anterior) -shape (trapezius) -action (extensor carpi ulnaris) -number of heads or divisions (triceps brachii) -attachments (sternocleidomastoid) -direction of the fibers (external oblique) -size of the muscle (pectoralis major) |
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Parallel Muscle Fibers |
-tend to be longer and thus have a greater range of motion potential -can be strap, fusiform, rhomboidal, or triangular in shape |
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Oblique Muscle Fibers |
-tend to be shorter but are more numerous per given area than parallel fibers -tend to have a greater strength potential but a smaller ROM potential than parallel-fibered muscles -can be unipennate, bipennate, or multipennate |
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Strap Muscle |
-those that are long and thin with fibers running the entire length of the muscle -Ex: sartorius, rectus abdominis, SCM |
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Fusiform Muscle |
-shape is similar to that of a spindle -wider in the middle and tapers at both ends where it attaches to tendons -most, but not all, fibers run the length of the muscle -Ex: biceps, brachialis, brachioradialis |
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Rhomboidal Muscle |
-four-sided, usually flat, with broad attachments at each end -Ex: pronator quadratus, rhomboids, gluteus maximus |
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Triangular Muscle |
-flat and fan-shaped -fibers radiate from a narrow attachment at one end to a broad attachment at the other -Ex: pectoralis major |
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Unipennate Muscle |
-look like one side of a feather -series of short fibers attaching diagonally along the length of a central tendon -ex: tibialis posterior, semimembranosus, flexor pollicis longus |
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Bipennate Muscle |
-looks like that of a common feather -fibers are obliquely attached to both sides of a central tendon -Ex: rectus femoris, interossei |
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Multipennate Muscle |
-many tendons with oblique fibers in between -Ex: deltoid, subscapularis |
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Muscle Normal Resting Length |
length of a muscle when it is unstimulated (when there are no forces or stresses placed upon it) |
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Muscle Irritability |
-aka excitability -ability to respond to a stimulus -can be from a motor nerve (natural) or electrical current (artificial) |
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Muscle Contractility |
-ability to shorten or contract (develop tension) when it receives adequate stimulation -may result in the muscle shortening, staying the same length, or lengthening |
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Muscle Extensibility |
ability to stretch or lengthen when a force is applied |
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Muscle Elasticity |
-ability to recoil or return to normal resting length when the stretching or shortening force is removed -a muscle is able to shorten beyond its normal resting length |
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Summary of Muscle Properties |
-stretch a muscle and it will lengthen (extensibility) -remove the stretch, and it will return to its normal resting position (elasticity) -stimulate a muscle, and it will respond (irritability) by shortening (contractility) -remove the stimulus and it will return to its normal resting position (elasticity) |
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Muscle Tension |
-the force built up within a muscle -stretching a muscle builds up passive tension (involves noncontractile units) -active tension comes from the contractile units -total tension of a muscle is a combo of passive and active tension -somewhat determined by muscle length |
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Muscle Tone |
-slight tension that is present in a muscle at all times, even when the muscle is resting -state of readiness that allows the muscle to act more easily and quickly when needed |
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Muscle Excursion |
-distance from maximum elongation to maximum shortening -usually sufficient enough to allow the joint to move through its entire range -in a one-joint muscle, excursion will be greater than ROM -in a two-joint muscle, excursion is less than combined ROM |
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Active Insufficiency |
-the point at which a muscle cannot shorten any farther -occurs to the agonist (muscle that is contracting) |
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Passive Insufficiency |
-occurs when a muscle cannot be elongated any farther without damage to its fibers -occurs to the antagonist (muscle that is relaxed and on the opposite side of the joint from the agonist) |
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Muscle Stretching |
-lengthens the resting length of a muscle -should be performed on relaxed muscles |
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Tenodesis |
-AKA tendon action of a muscle -the functional use of passive insufficiency |
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Isometric Muscle Contraction |
-occurs when a muscle contracts, producing force without changing the length of a muscle -muscle generates internal torque equal to external torque with no motion or change in joint angle |
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Isotonic Muscle Contraction |
-occurs when a muscle contracts and the muscle length and the joint angle change -can be subdivided into concentric and eccentric contractions |
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Concentric Contraction |
-AKA shortening contraction -occurs when there is joint movement, the muscles shorten, and the muscle attachments move toward each other -usually occurs against gravity ("raising" motion) -acceleration activity -torque produced internally by the muscle is greater than external torque produced by outside force |
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Eccentric Contraction |
-AKA lengthening contraction -occurs when there is joint motion, but the muscle appears to lengthen -muscle attachments separate -can produce much greater forces than a concentric contraction -usually occurs with gravity ("lowering" motion) -deceleration activity |
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Isokinetic Contraction |
-can be done only with special equipment -resistance to the part varies, but the velocity stays the same -if the person pushes harder, the machine will give more resistance -more resistance should be given while the muscle is in midrange -can be beneficial when dealing with pain |
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Roles of Muscles |
-depends on such variables as motion being performed, direction of motion, and the amount of resistance the muscle must overcome -can be agonist, antagonist, stabilizer, or neutralizer |
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Agonist |
-AKA prime mover -muscle or muscle group that causes the moving -usually becomes actively insufficient before antagonist becomes passively insufficient |
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Assisting Mover |
-agonist that is not as effective but does assist in providing motion -factors that determine prime vs. assisting: size, angle of pull, leverage, and contractile potential |
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Antagonist |
-muscle that performs the opposite motion of the agonist -has the potential to oppose the agonist, but is usually relaxed while the agonist is working |
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Cocontraction |
-when the antagonist contracts at the same time as the agonist -occurs when there is a need for accuracy -common when a person learns a task, especially a difficult one (as the task is learned, cocontraction activity tends to disappear) |
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Stabilizer |
-AKA fixator -muscle or muscle group that supports, or makes firm, a part and allows the agonist to work more efficiently |
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Neutralizer |
-contracts to prevent an unwanted motion (when a muscle can do two or more actions, but only one is wanted) -may also allow a muscle to perform more than one role |
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Synergist |
-muscle that works with one or more other muscles to enhance a particular motion -encompasses agonist and assists movers, stabilizers, and neutralizers -most meaningful body movements involve synergists |
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Force-Couple
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-produces force in different linear directions, but produce torque in same rotary direction |
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Angle of Pull |
-a major factor to determine muscle action -most muscles pull at a diagonal, a result of a vertical force and a horizontal force |
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Closed Kinetic Chain |
-requires that the distal segment is fixed (closed) and the proximal segment(s) moves -limb segments move in limited and predictable directions |
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Open Kinetic Chain |
-distal segment is free to move while the proximal segment(s) can remain stationary -limb segments are free to move in many directions |
