How do muscles move bones?
When a muscle acts to move a bone, it's point of origin (which is usually the end of the muscle closest to the axial skeleton) is held fairly stable so that the contraction of the muscle pulls the bone to which it inserts into towards it, in a lever-like action across the joint, which acts as a pivot.
Every muscle works with another muscle (or several others). The acting muscle is known as the agonist, and the 'partner' muscles are called the antagonists. The antagonist's action is the opposite of the agonist's action, and helps to control the movement and prevent injury.
In reality muscles usually work in groups rather than individually, to increase the stability and control of movement. For example the deltoid and supraspinatus work together to abduct the arm by contracting over the shoulder joint to pull on the humerus, as below :
The action of the deltoid
As another example, the brachioradialis and the biceps brachii work together across the elbow joint to flex the arm :
Reference : Human Physiology - Silverthorn (Amazon link)
Resources :
In this section we've added a few alternative study aids to help you along.
- Articles - Here you'll find a range of short articles on basic anatomy and physiology topics, complete with a few 'test yourself' questions for each one.
- Images and pdf's - Just in case you get tired of looking at the screen we've provided images and pdf files that you can print out and use for 'off-line' practice.
- Word Roots - When you learn the word roots, prefixes and suffixes contained within anatomical and medical terms, you can often work out what they mean. This can be a useful skill as you progress in your studies, so we've provided a dictionary to help you!
- Games - Finally in the resources section, we've added some simple games to make anatomy and physiology practice a little bit more fun.