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Terms in this set (91)
Bundles of muscle cells or fibers
Arrangement of the fasciculi
Muscles may be classified by their shape based on the __________ _____ _____ __________.
-Parallel (muscle fiber configuration)
-Pennate (muscle fiber configuration)
Muscle Fiber Configuration
Parallel (muscle fiber configuration)
The fibers or fasciculi are parallel to the tendon's long axis
Pennate (muscle fiber configuration)
The fibers lie at a non-parallel angle to the tendon's long axis; the tendon tends to run along the full length of the muscle
Pennate Configuration Types:
The muscle fibers lie along one side of the tendon
The muscle fibers lie on both sides of the tendon
The muscle fibers converge from several tendons
Angle of Pennation
The angle between pennate muscle fibers and the long axis of the tendon; determines forces directed to the tendon
Parallel Fiber Arrangement Example:
Penniform Fiber Arrangement Example:
Bipenniform Fiber Arrangement Example:
Multipenniform Fiber Arrangement Example:
Parallel Fibered Muscles
The muscle shortens as a direct relationship of the shortening of the muscle fibers (ex. if the fibers shorten by 3cm, then the entire muscle will shorten by 3cm)
Pennate Fibered Muscles
They rotate about their tendon attachment or attachments, progressively increasing their angle relative to the tendon (ex. if the fibers shorten by 3cm, then the entire muscle will shorten by 2cm)
SPEED of muscle contraction
-Faster contraction rate because they all shorten at the same time
FORCE of muscle contraction
-Higher concentration of fibers (fiber density)
-Can generate more force because there are a greater number of fibers
The amount of __________ in a contracted muscle is __________ throughout the muscle and it's active tendons from origin to insertions; force is uniform throughout the tendon.
Some __________ muscles may not develop tension in __________ heads during certain actions.
Torque; joints; resistance
The force produced by muscles creates __________ at the __________ (Tm) which is balanced against the torque produced by any __________ (Tr), including the resistance of the limb or body segment itself.
The type of contraction in the muscle is dependent on the relationship between torque produced by __________ and torque produced by __________.
If Tm>Tr the muscle __________ (__________ contraction)
If Tm<Tr the muscle __________ (__________ contraction)
Doesn't change; static/isometric
If Tm=Tr the muscle length __________ __________ (__________/__________ contraction)
Motor units in a given muscle are not all __________ at the same time, this allows for better __________ over movements.
Motor units are only activated as __________.
Activation order is generally determined by the __________ __________ of the fibers.
__________ __________ is generally determined by the twitch characteristics of the fibers.
Order of Recruitment:
Slow twitch oxidative
During low intensity activity __________ __________ __________ fibers may be recruited exclusively.
Fast twitch oxidative glycolytic; fast twitch glycolytic
As fatigue sets in, __________ __________ __________ __________ and then __________ __________ __________ fibers may become active until all fibers are activated.
Muscles which produce movement by concentric contraction
Primary Movers (Primary Agonists)
Always recruited for a given movement
Secondary Movers (Assistant Movers/Assistant Agonists)
Recruited when there is excess or additional resistance
Slow down or resist movement caused by agonists or an external force by means of eccentric contraction
Keep a limb or body segment in a rigid or fixed position by static or isometric contraction
Stabilizers keep a limb or body segment in a rigid or fixed position by __________ or __________ contraction.
Change the effect or direction of movement when a muscle or muscle group contracts
Neutralizers change the __________ or __________ of movement when a muscle or muscle group contracts
Lifting a weight
Lowering a weight
When muscles are producing movement by contracting concentrically they are said to be acting as __________.
When muscles slow down or control movement by contracting eccentrically, they are acting as __________.
Keeping a part of the body in a fixed position
When muscles lock a body segment in position by contracting statically or isometrically, they are acting as __________.
When muscles change or alter the direction of movement produced by another muscle or muscle group, they are acting as __________.
Multi-joint muscles are sometimes called __________ __________ if they cross two joints.
Multi-joint muscles are sometimes called __________ __________ if they cross two or more joints.
Muscles can produce or affect movement at any joint they cross
-Hamstring (knee flexion and hip extension)
-Gastrocnemius (knee flexion and plantar flexion)
-Rectus femoris (knee extension and hip flexion)
Examples of multi-joint muscles...
Multi-joint muscles can __________ to __________ movement.
The muscles thought to oppose each other actually assist each other when they act together
Disadvantages of Multi-Joint Muscles:
Occurs when multi-joint muscles can't contract enough to produce a full range of motion at all joints crossed (ex. the gastrocnemius produces little force in seated calf raises)
Occurs when tension in a multi-joint muscle reduces the range of motion in the opposite direction (ex. moving the wrist into a flexed position restricts finger flexion due to tension in the extensors of the fingers)
-Velocity (of muscle shortening)
-Length (of the muscle when it is stimulated)
-Electromechanical Delay (time interval between muscle stimulation and tension development)
Factors Affecting the Magnitude of Muscle Force
As concentric muscle force output __________ the rate at with it is capable of shortening __________.
A muscle shortens more __________ against __________ resistance.
For a concentric contraction, as velocity of shortening __________, force output __________.
In an eccentric contraction, as resistance __________ beyond the isometric limit, the muscle begins to __________.
For an eccentric contraction, as resistance __________, the rate of lengthening __________.
-More effective increase in muscle size and strength than with concentric training
-More soreness and structural damage than with concentric or isometric training
Effects of Eccentric Training
Effective increase; size; strength; soreness; structural damage
Effects of Eccentric Training:
-More __________ __________ in muscle __________ and ___________ than with concentric training
-More __________ and __________ __________ than with concentric and isometric training
Maximum potential isometric force is partly dependent on muscle length
Maximum potential __________ force is partly dependent on muscle __________.
Produced by activation of the motor unitis
__________ __________ is greatest when the muscle is at its resting length.
Greatest; resting length
Active tension is __________ when the muscle is at its __________ __________.
__________ __________ decreases as muscle length goes above or below resting length.
Decreases; above; below
Active tension __________ as muscle length goes __________ or __________ resting length.
Muscle length; resting length
Active tension decreases as __________ __________ goes above or below __________ __________.
Produced by the parallel elastic component and the series elastic component
Parallel elastic component; series elastic component
Passive tension is produced by the __________ __________ __________ and the __________ __________ __________.
__________ __________ increases as the muscle is stretched beyond its resting length (this is primarily due to the series elastic component)
Increases; stretched beyond; resting length
Passive tension __________ as the muscle is __________ __________ its __________ __________.
Series elastic component
Passive tension is primarily due to the __________ __________ __________.
Total muscle tension is a result of the addition of __________ and __________ tension.
__________ __________ muscles generate maximum tension when stretched to slightly more than resting length.
__________ __________ muscles generate maximum tension when stretched over 100% of resting length.
The lapse in time between electrical activation of a muscle and the development of tension
Time; electrical activation; tension
The electromechanical delay is the lapse in __________ between __________ __________ of a muscle and the development of __________.
Series elastic component; laxity
The electromechanical delay is believed to be the time required to stretch the __________ __________ __________, therefore removing __________ from the muscle.
Fast twitch fibers
A shorter electromechanical delay is related to a higher percentage of __________ __________ __________.
Higher contraction forces are associated with __________ electromechanical delays.
-Type of contraction
-Velocity of contraction
Doesn't affect Electromechanical Delay...
It may take a full __________ for a muscle to develop maximum isometric tension following the electromechanical delay.
Electromechanical delay in __________ is significantly longer than in __________.
Electromechanical delay in children is significantly __________ than in adults.
The force generated by a muscle depends on the total number of __________ __________ __________.
Higher __________ produce greater __________.
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