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Depiction of smooth muscle contraction. Muscle contraction is the activation of tension-generating sites within muscle cells. [1] [2] In physiology, muscle contraction does not necessarily mean muscle shortening because muscle tension can be produced without changes in muscle length, such as when holding something heavy in the same position. [1]
Muscle injury (such as a large burn or surgery) can cause muscle contractures as internal scar tissue (adhesions and fibrosis) develops. Repetitive muscle injuries (e.g. sports injuries, major muscle strains) and micro-injuries (e.g. overuse injuries, minor muscle strains) can also cause this. Adhesions and fibrosis are made of dense fibrous ...
In pathology, a contracture is a shortening of muscles, tendons, skin, and nearby soft tissues that causes the joints to shorten and become very stiff, preventing normal movement. [ 1 ] [ 2 ] A contracture is usually permanent, but less commonly can be temporary (such as in McArdle disease ), [ 3 ] or resolve over time but reoccur later in life ...
The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. [1] According to the sliding filament theory, the myosin ( thick filaments ) of muscle fibers slide past the actin ( thin filaments ) during muscle contraction, while the two groups of filaments ...
Myofascial pain is associated with muscle tenderness that arises from trigger points, focal points of tenderness, a few millimeters in diameter, found at multiple sites in a muscle and the fascia of muscle tissue. Biopsy tests found that trigger points were hyperirritable and electrically active muscle spindles in general muscle tissue. [13]
The muscle fibers belonging to one motor unit can be spread throughout part, or most of the entire muscle, depending on the number of fibers and size of the muscle. [ 2 ] [ 3 ] When a motor neuron is activated, all of the muscle fibers innervated by the motor neuron are stimulated and contract.
Origin refers to a site where the muscle attaches to a bone that remains stationary during a contraction, and insertion refers to a site where a muscle attaches to a bone that moves during a ...
The stretch reflex (myotatic reflex), or more accurately "muscle stretch reflex", is a muscle contraction in response to stretching a muscle. The function of the reflex is generally thought to be maintaining the muscle at a constant length but the response is often coordinated across multiple muscles and even joints. [1]