Ch. 2 - Muscle Terminology/Contraction/Role/Action Flashcards
Tendon
tough yet flexible bands (rope-like) of fibrous connective tissue that connect muscles to bones and other structures
- transmit the force generated by the muscles to the bone
Origin
- proximal/closest attachment to the midline or center of body
- functional: the least movable/most stable part of attachment of a muscle
Insertion
- the distal/farthest from the midline or center of the body
- functional: the most movable part of a muscle
Contraction
tension that is developed in a muscle as a result of a stimulus
- can be used to cause/initiate, control (accelerate/decelerate), or prevent joint movement
Isometric/static movement
tension is developed within the muscle but the joint angles remain constant
- used to stabilize, or maintain the joint angle
Isotonic/dynamic movement
muscle developing tension to either cause or control joint movement
- cause joint angles to change
Concentric
- isotonic movement
- muscle developing active tension as it shortens, causing movement against gravity, accelerate a body part to a higher speed
Eccentric
- isotonic movement
- muscle lengthening under active tension, controlling the descent of the resistance, decelerate the movement of a body segment
- more likely to cause injury
Isokinetics
dynamic exercise using concentric and/or eccentric muscle contractions
- speed is constant
- muscular contraction (ideally maximum contraction) occurs
- not a type of contraction
Agonist
aid in the movement of a joint, through a specified plane when contracting concentrically
- prime mover: muscles that contribute significantly to causing a specific joint movement when contracting
Antagonist
located on the opposite side of the agonist, and assist in the movement; or will perform the opposite action of the agonist
- contralateral muscles
Stabilizer
contract to fixate or stabilize the area to enable another limb or bod segment to exert force and move
- ex: the shoulder muscles and triceps when doing a bicep curl
Synergist
assist in the action of an agonist but are not necessarily prime movers, usually guide muscles
Helping synergist
have an action common to each other, but also have action antagonistic to each other; help the muscle move a joint but also prevent undesired actions
True synergist
contract to prevent an undesired joint action of the agonist and have no effect on the agonist action
Neutralizer
counteract or neutralize the action of other muscles to prevent undesirable movements
Force couples
occur when two or more forces are pulling in different directions to make one movement on an object, causing the object to rotate about its axis
- ex: serratus anterior, middle and lower trap. causing the scapula to rotate
Tying roles of muscles together: kicking a ball
- hip flexors and knee extensors are agonists
- hamstrings are antagonists
- precision depends on many other muscles
How can muscle action be determined?
- line of pull
- description of the direction of force exerted by a muscle, depending on the orientation of its fibers, skeletal attachments, the disposition of its tendons, and the axis of movement of any joints affected
How else can muscle action be determined?
- palpation (limited by location of muscle, type of movement, legality)
- electromyography
- electrical muscle stimulation
All or none principle
All muscle fibers will be recruited/activated or none at all
Motor unit
Single motor neuron and all the muscle fibers it innervates
Latent period
Brief period of milliseconds following a stimulus
Contraction phase
Muscle fiber begins shortening, lasts about 40 ms
Relaxation phase
Follows contraction phase, lasts about 50 ms
Summation
Stimuli is provided before relaxation phase, produces sustained and greater tension
- the longer the fibers, the longer a summation can be
Tetanus
All muscle fibers have reached max tension, stimulus is being provided at a frequency high enough that no relaxation can occur btwn contraction
Supramaximal stimulus
All muscle fibers are recruited
