How skeletal muscles work
Skeletal muscles work in pairs & contract to create movement, this is possible due to the protein myofilaments known as actin & myosin which move over each other, shortening the myofibril in a process known as the sliding filament theory. Many myofibrils contracting and shortening together in multiple muscle fibres produce a shortening of the muscle fasciculi which results in the contraction of the whole muscle belly enabling movement to occur
Watch this blog post here...
You are now looking at a close up of a muscle fibre which includes many myofibrils within it. Each individual myofibril consist of chains of sarcomeres, it is these sarcomeres which are the contractile units of muscle & consist of the protein myofilaments (actin & myosin). Actin are the thin, outer filaments that are drawn together during a concentric contraction, myosin are the thicker, inner filaments which have projecting heads for connecting, to the actin filaments during muscle contraction.
This contraction is known as the sliding filament theory, and is triggered by the somatic nervous system and powered by the high energy molecule adenosine triphosphate (or ATP) which is present at the myofilament site. The actin and myosin myofilaments do not decrease in length themselves during muscular contraction, they slide over each other, shortening the length of the sarcomere as seen in the here.