L4 Flashcards
The deltoid muscle crosses the shoulder joint and can do which joint actions?
Flexion, Extension, and Abduction
The soleus muscle crosses the ankle joint and can do which joint actions?
Plantarflexion
Internal Motors that contribute to movement
Skeletal muscle
-voluntary tissue
4 Tissue properties of skeletal muscle?
Irritability (excitability), Contractibility, Extensibility, Elasticity
ICEE
Irritability (excitability)
Permits muscles the ability to respond to stimulation
Contractibility
Permits muscles the ability to shorten and produce the necessary tension to move the skeletal system
Extensibility
Permits muscle the ability to lengthen or stretch past its normal resting length
Elasticity
Permits the muscle to return to its resting length after the stretch is removed
Functions of Muscle
Produce Movement, Maintain Postures and Positions, Stabilize Joints, support and protect organs, produce tension
Muscles can attach:
Directly to the bone by attaching to the periosteum (a thin covering on the outside of bone)
Via a tendon that is fused with the muscle fascia
Via aponeurosis (fibrous connective tissue sheath that remits muscles to increase attachment to bone by widening the area of attachment)
Fusiform/ Parallel Muscle
The fiber force is in the same direction as the musculature-muscles are generally long and thin
-greater ROM and greater movement velocity
Pennate Muscle
-fibers run diagonally running the length of the muscle (greater cross-sectional area)
-generally short and thick
-utilize Contractibility property to provide greater force production in movements
2 Classifications on how muscles cross joints:
Uniarticular and Multiarticular
Uniarticular Muscles:
Cross only one joint
Advantage: can contribute every part of it to the intended joint without becoming an opponent to itself
-majority of muscles in human body
Multiarticular Muscles
Cross multiple joints in the human body
Advantages: transfer mechanical energy between segments (concentrically contract at one end and eccentrically coontract at the other) -allows muscle to store elastic energy
-redistribute loads placed upon joint (reduce/ absorb or increase stored mechanical energy)
Functional Roles of Muscles (4)
Agonist: muscles produce force in same direction as the joint action
Antagonist: muscles produce force opposite to the agonists joint angle
Stabilizer: stabilize a bone at one end so that a movement in an adjacent segment can occur
Neutralizer: contract to eliminate an undesired joint action of another muscle
In shoulder abduction:
The deltoid is the agonist because responsible for abduction
The lets are antagonistic because it resists ab
The traps stabilize and hold the scapula
Teres minor neutralizes
Torque:
The tendency of a force to produce rotation about a specific axis
How is force generated in the muscle
Along the line of action of the force and applied to bone
Concentric muscle action
Shortening, least muscle force, muscles overcome external resistance
Eccentric muscle action
Lengthening,greatest force production, muscle can’t overcome external force
Isometric muscle action
Length stays the same, medium force, no movement
Muscle structure properties (4)
Muscle connects to bones via tendon or aponeurosis
Fibers are bundled into fascicles
Fibers contain myofibril strands that run the length of the fiber
The actual contractile unit is the sarcomere
3 types of muscle fibers: type 1
Type I: oxidative - slow contraction times und prolonged, low intensity work, fatigue resistant
3 types of muscle fibers: type 2a
Intermediate fast twitch and are consistent for lung periods with a burst of force and then fatigue more force than type I
3 muscle fiber types: type 2b
Rapid force production but fatigue quickly
Sliding filament theory:
Sarcomere contracts, cross bridges are formed between the head of the myosin and a prepared site on the actin filament
Myosin head pulls on actin, filaments move toward each other causing shortening/ contraction
3 Components of Mechanical Model of Muscle: Contractile
Converts stimulation of NS into force and reflects shortening of muscle through actin and myosin structures
Series Elastic Component: SEC
-all elastic elements in series with the force generating structures of the muscle
Parallel elastic component: PEC
-displays elasticity when CC is not producing force
Stretch Shortening Cycle
(Preloading of Muscle)
Stretch on muscle increases tension through storage of toenail elastic energy
-following concentric contraction is enhanced by previously stored elastic energy
Maximum tension of muscle is reached where
Isometric state
-most cross bridges
-shortens and lengthens hard
