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Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the voluntary muscular system [ 1 ] and typically are attached by tendons to bones of a skeleton .
Skeletal muscle, is a type of striated muscle, composed of muscle cells, called muscle fibers, which are in turn composed of myofibrils. Myofibrils are composed of sarcomeres, the basic building blocks of striated muscle tissue. Upon stimulation by an action potential, skeletal muscles perform a coordinated contraction by shortening each sarcomere.
Striated or skeletal muscle only contracts voluntarily, upon the influence of the central nervous system. Reflexes are a form of non-conscious activation of skeletal muscles, but nonetheless arise through activation of the central nervous system, albeit not engaging cortical structures until after the contraction has occurred. [citation needed]
The movement performed by the muscle from the standard anatomical position. In other positions, other actions may be performed. Antagonist The muscle which can 'cancel' or to some degree reverse the action of the muscle. Muscle synergies are noted in parentheses when relevant. O (Occurrences)
Only skeletal and smooth muscles are part of the musculoskeletal system and only the muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood; like the smooth muscles, these muscles are not under conscious control. Skeletal muscles are attached to bones and arranged in opposing groups around joints. [8]
Diagram of skeletal muscle fiber structure. Skeletal muscle cells are the individual contractile cells within a muscle and are more usually known as muscle fibers because of their longer threadlike appearance. [10] Broadly there are two types of muscle fiber performing in muscle contraction, either as slow twitch or fast twitch .
A diagram of the structure of a myofibril (consisting of many myofilaments in parallel, and sarcomeres in series) Sliding filament model of muscle contraction. The myosin heads form cross bridges with the actin myofilaments; this is where they carry out a 'rowing' action along the actin. When the muscle fibre is relaxed (before contraction ...
Movement is powered by skeletal muscles, which are attached to the skeleton at various sites on bones. Muscles, bones, and joints provide the principal mechanics for movement, all coordinated by the nervous system. It is believed that the reduction of human bone density in prehistoric times reduced the agility and dexterity of human movement.