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[14] [15] There are between 600 and 840 muscles within the typical human body, depending on how they are counted. [ 16 ] [ 17 ] [ 18 ] In the present table, using statistical counts of the instances of each muscle, and ignoring gender-specific muscles, there are 753 skeletal muscles.
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.
The heart, liver and red blood cells will also consume lactic acid produced and excreted by skeletal muscles during exercise. Skeletal muscle uses more calories than other organs. [69] At rest it consumes 54.4 kJ/kg (13.0 kcal/kg) per day. This is larger than adipose tissue (fat) at 18.8 kJ/kg (4.5 kcal/kg), and bone at 9.6 kJ/kg (2.3 kcal/kg).
Different skeletal muscle types: A: fusiform. B: unipennate. C: bipennate. (PCS: physiological cross-section) Muscles may also be described by the direction that the muscle fibers run, in their muscle architecture. Fusiform muscles have fibers that run parallel to the length of the muscle, and are spindle-shaped. [19]
Skeletal muscle is voluntary muscle, anchored by tendons or sometimes by aponeuroses to bones, and is used to effect skeletal movement such as locomotion and to maintain posture. Postural control is generally maintained as an unconscious reflex, but the responsible muscles can also react to conscious control.
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]
Physical activity is defined as any voluntary bodily movement produced by skeletal muscles that requires energy expenditure. [1] Physical activity encompasses all activities, at any intensity, performed during any time of day or night. [2] It includes both voluntary exercise and incidental activity integrated into the daily routine. [3]
Dorsiflexion of the foot: The muscles involved include those of the Anterior compartment of leg, specifically tibialis anterior muscle, extensor hallucis longus muscle, extensor digitorum longus muscle, and peroneus tertius. The range of motion for dorsiflexion indicated in the literature varies from 12.2 [8] to 18 [9] degrees. [10]