Why do muscles need multiple heads? and are all the heads in some muscles attached all on the same bone, as far as I remember the triceps attaches at least in two different places at the superior end. into the coracoid process and the clavicle.but i wonder other muscules like one of the facial muscles that is a bipennate muscle probably has to attachments would it cause something to move in two different directions depending on which tendon it pulls on?

Pretty much the functional definition of a head is that it attaches differently and has a altered somatic action. Take a look at the different motion created by the long and short head of biceps brachii - it is a good example as the head end is fairly simple mechanically (the tendon connection to the lower arm is less simple) . Actually triceps might be a better example as it is almost alone as a single muscle group - but the connexions and thus functions are less easy to follow.

 

I mentioned Triceps as it is fairly isolated and can act solely - but this is very rare; muscles do not tend to be stimulated as individuals - they are stimulted in functional groups. This is particularly important in complex areas with numerous muscles many of which are complex in of themselves - such as the area of the face and hands. there are very few movements that can be tracked to the certain stimulation of an individual muscle - most movements are a combination of agonist muscles often with antagonists thrown in to stabilise.

now I understand thank you