# Muscles Part 2

## muscle tension

* isotonic, movement
	* concentric - shorten
	* eccentric - lengthen	
* isometric, no movement

always needs nervous system input

difference between stability and movement basically

## Motor units and recruitment

neurons that go to specific fibers

motor unit - plus muscle fibers that it communicate with. allows for changing value of force used.

activate muscles in rotation - so we avoid over stressing

dont use till it is no longer working. just rotate so that the transitions are less jaring

## Muscles rarely completly relax
muscle tone when not flexing is because of higher muscle density

hypertonia - too few recruited muscles (unable to move)

hypertonia - too muchj muscle stress (unable to relax)


## Skeletal Muscle Movement
* form dictates function
	* muscles are attached to bones to allow for movement
* muscle origin - anchor point (bicept on the humerous /scapulus)
* muscle insertion - (bicept to radius)


you will have a chart of origin, insertion, action

elbow hinge joint
muscles are with joints

## Muscles (almost) never work alone
* aiding, opposite work together

prime mover/ agonist -> main muscle moving things

synergist -> assits movement

antagonist -> opposite movement of agonist
* maintains body position
* needed for rapid movement