What are myofilaments?
Myofilaments are protein in nature, present in muscle fibre.
Within each muscle fiber are hundreds of parallely arranged myofibrils. Each myofibril is made up of bundles of the protein filaments (myofilaments) that are responsible for muscle contraction.
The 2 types of myofilaments are: thin filaments: made of the protein actin , and thick filaments: made of the protein myosin . Myofilaments are arranged to form repeating units termed sarcomeres .
During a contraction, myosin heads interact with actin filaments to form cross-bridges. The myosin head pivots, producing motion. This motion "pulls" the actin.
The actin is attached at the ends of the sarcomere. The ends do not move but actins are pulled closer towards the middle of sarcomere by the myosin heads.
Click here for an animation that will help explain this. Note that calcium is necessary for this action. sliding filament