Joints and Muscles

What kind of muscles are responsible for movement?

striated voluntary muscles

What do muscle attachments tell us?

The connection of muscle to bone and help tell you motion

isometric

holds
muscle does not change length

eccentric

muscle lengthens

the muscle is exerting more (internal) torque on the joints than the external torque caused by external forces

concentric activation

what muscle activation is when you go up in a push up?

concentric (muscle is winning)
elbow extension
elbow extensors

what muscle activation is when you go down in a push up?

eccentric
elbow flexion
elbow extensors

extensibility

stretching movement of a muscle

irritability

response to stimuli (excitability)

contractability

ability to shorten

parallel "fusiform" muscle fibers

fewer muscle fibers in an area (less force, less strength)

active tension

occurs during activation of muscle tissue (moving)

passive tension

occurs due to the elongation or during lengthening of muscle tissue (stretch)

passive insufficiency

when a multi-joint muscle cannot be ELONGATED further without damage to fibers (or body compensates)

What do muscle names tell you?

location
attachments
shape
action
# of heads

how does muscle force and joints interact?

movement
stability
instability

concentric

muscle shortens

occurs when the external torque is greater than the internal torque of the muscle

eccentric activation
muscles are still working! controlled, active motion

internal and external torques are equal

isometric activation
muscles are still working! no motion at the joint

agonist

prime mover
producing muscle activation

antagonist

muscle opposite to the prime mover

synergist

muscle helping the prime mover
produces motion, stabilizes during motion, and prevents unwanted motion of antagonists

elasticity

ability to return to resting length (without damage)

viscosity

resistance to external forces (heat, ice)

what is the difference between men and women in force production?

men: more muscle bulk and fiber
women: less than men, but if had same -- could produce equal force

slower concentric activation --> ________?

greater force (more time to form actin-myosin bonds)

faster concentric activation --> _______?

less force (less time to form actin-myosin bonds)

pennate "oblique" muscle fibers

more muscle fibers in an area (greater force, greater strength)

what determines strength of muscle activation?

physiological cross-sectional area of fibers

what is the optimal length for developing maximal active force?

close to the resting length

active insufficiency

when a multi-joint muscle cannot produce additional ACTIVE force due to SHORTENED length

tenodesis

passive tendon action
muscles or tendons cross multiple joints
can be used functionally to provide grasp (wrist flexion/finger extension and wrist extension/finger flexion)
uses passive insufficiency

what are passive components that influence strength?

fascia, muscle tissue, and tendons