Muscle is a soft tissue of animals. Muscle cells contain protein filaments that slide past one another, producing a contraction that changes both the length and the shape of the cell. Muscles function to produce force and cause motion. They are primarily responsible for maintenance of and changes in posture, locomotion of the organism itself, as well as movement of internal organs, such as the contraction of the heart and movement of food through the digestive system via peristalsis.
Muscle tissues are derived from the mesodermal layer of embryonic germ cells. They are classified as skeletal, cardiac, or smooth muscles. Cardiac and smooth muscle contraction occurs without conscious thought and is necessary for survival. Voluntary contraction of the skeletal muscles is used to move the body and can be finely controlled. Examples are movements of the eye, or gross movements like the quadriceps muscle of the thigh.
Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules which are used to power the movement of the myosin heads.
The term muscle is derived from the Latin musculus meaning "little mouse" perhaps because of the shape of certain muscles or because contracting muscles look like mice moving under the skin.
Other articles related to "muscles, muscle":
... Muscles have evolved at least twice, once in cnidaria and once in bilateria they seem to have evolved from contractile cells in sponge-grade organisms ... Evolutionarily, specialized forms of skeletal and cardiac muscles predated the divergence of the vertebrate/arthropod evolutionary line ... This indicates that these types of muscle developed in a common ancestor sometime before 700 million years ago (mya) ...
... even crossing, in a scissors-like movement while the opposing muscles, the abductors, become comparatively weak from lack of use ... palsy, the individual is often also forced to walk on tiptoe unless the plantarflexor muscles are released by an orthaepedic surgical procedure ... at the knee adduction and internal rotation at the hip progressive contractures of all spastic muscles complicated assisting movements of the upper limbs when walking ...
... of the arterial blood … we suggest that, in the body (either in the heart muscle itself or in the nervous system), there is some mechanism which causes a slowing of the circulation as soon as a ... a mechanical failure of the exercising muscles ("peripheral muscle fatigue") ... by an inadequate oxygen supply to the exercising muscles, lactic acid buildup, or total energy depletion in the exhausted muscles ...
... L5 supplies many muscles, either directly or through nerves originating from L5 ... The muscles are gluteus maximus muscle mainly S1 gluteus medius muscle gluteus minimus muscle tensor fasciae latae tibialis anterior tibialis posterior extensor digitorum brevis extensor hallucis ...
... Muscle force is proportional to physiologic cross-sectional area (PCSA), and muscle velocity is proportional to muscle fiber length ... parameters, including the distance between muscle insertions and pivot points and muscle size ... Muscles are normally arranged in opposition so that as one group of muscles contract, another group relaxes or lengthens ...
Famous quotes containing the word muscles:
Flashed from his matted head and marble feet,
He grappled at the net
With the coiled, hurdling muscles of his thighs:
The corpse was bloodless, a botch of reds and whites,”
—Robert Lowell (19171977)
“Biological possibility and desire are not the same as biological need. Women have childbearing equipment. For them to choose not to use the equipment is no more blocking what is instinctive than it is for a man who, muscles or no, chooses not to be a weightlifter.”
—Betty Rollin (b. 1936)
“What is this beast, she thought,
with muscles on his arms
like a bag of snakes?
What is this moss on his legs?
What prickly plant grows on his cheeks?
What is this voice as deep as a dog?”
—Anne Sexton (19281974)