Exercise Science chap 2
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movement of a joint from a concentric contraction of a muscle that crosses the joint.
ex. biceps brachii
Range of muscle fiber length btwn maximal and minimal lengthening
belly or body. central fleshy portion of the muscle that generally increases in diameter as the muscle contracts.
muscles that arise or originate outside of (proximal to) the body part on which the act.
segment of the nervous system responsible for providing a stimulus to muscle fibers within a specific muscle or portion of a muscle.
muscles within the body part on which they act.
ex. the small intrinsic muscles found entirely within the hand
fibrous connective tissue. cordlike, connects muscles to bones and other structures. 2 muscles may share a common tendon ex. achilles tendon of the gastrocnemius and soleus muscles
A muscle can also have multiple tendons connecting it to one or more bones. ex. the 3 proximal attachments of the triceps brachii.
structurally: the proximal attachment of a muscle or the part that attaches closest to the midline of the body
functionally: the least movable part or attachment of the muscle.
structurally: distal attachment or the part that attaches farthest from the midline of the body.
functionally: the most movable part.
Example of Origin and Insertion: Bicep curls
Muscle: Biceps Brachii
- Origin: scapula (least movable)
- Insertion: radius (most movable)
these movements can be reveresed. ex doing pull ups instead of curls.
tension is developed within the muscle, but joint angles remain constant. aka static contractions because it can be used to stabilize a body segment to prevent it from being moved by external forces
the muscle develops tension to either cause or control joint movement. aka dynamic contractions because the varying degrees of tension in the muscles are causing the joint angles to change.
the muscle developing tension as it shortens and occurs when the muscle develops enough force to overcome the applied resistance. A causing movement against gravity or resistance. Positive contractions. The joint angle is changed in the direction of the applied force.
eccentric contraction (muscle action)
muscle lengthening under tension. occurs when the muscle gradually lessens in tension to control the descent of the resistance. control movements with gravity or resistance. negative contractions. force developed by the muscle is less than that of the resistance. joint angle is changed in the direction of the resistance or external force.
a specific technique that may use any or all of the different types of contractions. A type of dynamic exercise using concentric and/or eccentric muscle contractions
muscles that, when contracting concentrically, cause joint motion through a specified plane of motion. aka prime movers or muscles most involved.
muscles that are located on the opposite side of the joint from the agonist and have the opposite concentric action. aka contralateral muscles. They work in cooperation w agonist muscles by relaxing and allowing movement, but when contracting concentrically they perform the opposite joint motion of the agonist.
muscles that surround the joint or body part and contract to fixate or stabilize the area to enable another limb or body segment to exert force and move. aka fixators. essential for more distal joints
muscles that assist in the action of agonists but are not prime movers for the action. aka guiding muscles. they assist in refined movement and rule out undesired motions.
muscles that counteract or neutralize the action of other muscles to prevent undesirable movements such as inappropriate muscle substitutions
highest level of control. provides for the creation of voluntary movement as aggregate muscle action, but not as specific muscle activity.
level after C.C. controls the maintenance of postures and equilibrium and learned movements such as driving a car. sensory integration for balance and rhythmic activities is controlled here.
3rd. a major integrator of sensory impulses and provides feedback relative to motion. it controls the timind and intensity of muscle activity to assist in the refinement of movements.
last. integrates all CNS activity through excitation and inhibition of desired neuromuscular actions and functions in arousal or maintaining a wakeful state.
or sensory nerves bring impulses from receptors in the skin, joints, muscles, and other peripheral aspects of the body to the CNS
or motor nerves carry impulses to the outlying regions of the body.
the subconscious mechanism by which the body is able to regulate posture and movement by responding to stimuli originating in the proprioceptors imbedded in the joints, tendons, muscles, and inner ear.
ex. stepping on unlevel ground unexpectedly and your muscles adapt to the situation.
the conscious awareness of the position and movement of the body in space.
a single motor neuron and all of the muscle fibers it innervates. They function as a single unit.
stimuli that are stronger to the point of producing action potentials in additional motor units.
when the stimulus becomes strong enough to produce an action potential in a single motor unit contract. all of the muscle fibers in the motor unit contract.
a stimulus via an electrical signal from the brain and spinal cord through its axons.
another phenomenon of muscle contraction that occurs when multiple maximal stimuli are provided at a low enough frequency to allow complete relaxation btwn contractions to rested muscle.
stimuli are provided at a frequency high enough that no relaxiation can occur btwn contractions.
lasts about 50 milliseconds
2nd phase. begins in which the muscle fiber begins shortening. lasts about 40 milliseconds. followed by the relaxation phase.
to simplify the phases of a single muscle fiber contraction or twitch, a stimulus is provided and followed by a latent perod.
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