red muscle

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red mus·cle

slow-twitch muscle in which small dark "red" muscle fibers predominate; myoglobin is abundant and great numbers of mitochondria occur, characterized by slow, sustained (tonic) contraction. Contrast with white muscle.
One of the two main types of skeletal muscle, which contains abundant mitochondria and myoglobin. Red muscle fibres contract and fatigue more slowly than white fibres and generate ATP by aerobic catabolism of glucose and fats, utilizing myoglobin-bound O2

red mus·cle

(red mŭs'ĕl)
Slow-twitch muscle in which small dark "red" muscle fibers predominate; myoglobin is abundant and great numbers of mitochondria occur, characterized by slow, sustained (tonic) contraction.

muscle fibre types

categories of muscle fibre adapted for various modes of use. Normally taken to refer to skeletal muscle unless specified otherwise. The main types found in stable human skeletal muscles after infancy are shown in the table. Intermediate 'hybrid' forms also occur, commonly in non-stable states such as during intensive or recently changed training regimes, or in recovery from injury. Types termed 1, 2A and 2B, containing myosins similarly designated, have been recognized since about 1970; however, the separate existence in many mammals of type 2X (initially also known as 2D), distinguishable from 2B only by sophisticated techniques, was recognized during the 1990s and it is now accepted that most, if not all, human fibres formerly called 2B in fact have 2X myosin. The slower-contracting muscles have a majority of type 1 fibres (typically approaching 90% in the extreme instance, soleus), while the faster-contracting ones have rather more, and often rather larger, type 2. Only some small specialist muscles (e.g. extraocular) have 80-85% fast fibres; in large limb muscles above 60% fast is reported only for sprint athletes. See also muscle enzymes. See table below .
Table 1: Characteristics of the three main types of stable human skeletal muscle fibres
Fibre type and myosin type12A2X (formerly '2B')
DescriptionSlow (-twitch) redFast (-twitch) redFast (-twitch) white
Principal energy supply systemOxidativeOxidative and glycolyticGlycolytic (anaerobic)
Abbreviated descriptionSOFOGFG
Mitochondrial densityHighMedium to very highLow
Motor neuron sizeSmallMediumLarge
Contraction speedSlowFairly fastFast
Fatigue resistanceHighMedium to highLow
Myosin ATPase activity after pH ∼ 10.3 pre-treatmentLowFairly highHigh
Ditto, after pH 4.6 pretreatmentHighLowMedium
Ditto, after pH 4.3 pretreatmentHighLowLow


an organ composed of bundles of fibers that has the power to contract and hence to produce movement. Muscles are responsible for locomotion and help support the body, generate heat and perform a number of other functions. They are of two varieties: striated (or striped, voluntary or skeletal), which makes up most of the meat of a carcass, and smooth (unstriated), which includes all the involuntary muscle of the viscera, heart and blood vessels.
Skeletal muscle fibers range in length from a few millimeters to many centimeters. They also vary in color from white to deep red. Each muscle fiber receives its own nerve impulses, which trigger fine and varied motions. At the signal of an impulse traveling down the nerve, the muscle fiber changes chemical energy into mechanical energy, and the result is muscle contraction. At least two major types of muscle fiber have been identified by histochemical techniques: type I (red) fibers, which have a slow contraction; and type II (white) fibers, which have a fast contraction.
Some muscles are attached to bones by tendons. Others are attached to other muscles, and to skin, producing, for example, the skin twitch, the eye blink and hair erection. Parts of the walls of hollow internal organs, such as the heart, stomach and intestines and also blood vessels, are composed of muscles. See also muscular. For a complete list of named muscles see Table 13.

agonistic muscle
prime mover; a muscle opposed in action by another muscle, called the antagonist.
antagonistic muscle
one that counteracts the action of another muscle (the agonist).
appendicular muscle
one of the muscles of a limb.
arrector pili muscle
small, smooth muscle attached to the bulb of the hair which causes erection of the hair and compression of the attending sebaceous gland when it contracts.
arterial muscle
part of the tunica media; smooth muscle fibers arranged in a circular pattern around the lumen.
articular muscle
one that has one end attached to the capsule of a joint.
axial muscle
1. muscles derived from the somites in the embryo.
2. the muscles around the vertebral column.
muscle biopsy
sample of living muscle obtained by excision or punch.
cardiac muscle
striated involuntary muscle with branched fibers and containing modified fibers which act as cardiac conducting cells.
congenital muscle defects
may be environmental, e.g. nutritional muscular dystrophy, or inherited, e.g. splayleg of piglets.
congenital type II muscle fiber hypertrophy
occurs in the hip joint musculature in German shepherd dogs but there is no detectable abnormality of gait.
cutaneous muscle
striated muscle that inserts into the skin.
double muscle
see myofiber hyperplasia.
esophageal muscle
the tunica muscularis of the esophagus in most domestic animals is mostly striated; in pigs, horses and cats there are small segments of smooth muscle; in birds the entire tunic is smooth muscle.
extraocular m's
the six or seven voluntary muscles that move the eyeball: dorsal, ventral, medial and lateral recti, dorsal and ventral oblique, and retractor bulbi muscles.
extrinsic muscle
one that originates in another part than that of its insertion, e.g. those originating outside the eye, which move the eyeball.
fast-twitch skeletal muscle
two of the three types of skeletal muscle are pale in color and fast-twitch—type IIa (fast-twitch oxidative-glycolytic), type IIb (fast-twitch glycolytic). Type IIa fibers are fatigue-resistant, type IIb fatigue easily.
muscle fiber
see muscle (above).
fixation m's, fixator m's
accessory muscles that serve to steady a part.
hamstring m's
the biceps, semimembranosus and semitendinosus muscles. See also hamstring.
intraocular m's
the intrinsic muscles of the eyeball.
intrinsic muscle
one whose origin and insertion are both in the same part or organ, such as those entirely within the eye.
involuntary muscle
see smooth muscle (below).
iridial muscle
layers of circular (sphincter) and radial (dilator) muscles. See also iris.
jaw muscle
see Table 13.1H muscles of mastication.
laryngeal muscle
see Table 13.1E muscles of the larynx.
limb muscle
see Table 13.3, 13.4 muscles of the fore- and hindlimbs.
masseter muscle
the principal muscle of mastication. See also Table 13.1H.
mylohyoid muscle
see Table 13.1D muscles of the hyoid apparatus.
muscle neoplasms
of striated muscle—rhabdomyoma, rhabdomyosarcoma; of plain muscle—leiomyoma, leiomyosarcoma.
muscle nonstriated
see smooth muscle (below).
orbicular muscle
one that encircles a body opening, e.g. the eye or mouth.
muscle-paralyzing drugs
drugs which produce neuromuscular blockade, used as muscle relaxants during surgical procedures. Include d-tubocurarine, alcuronium chloride, pancuronium, vecuronium, atracurium besylate, succinylcholine.
red muscle
type 1 fibers predominate with slow contraction cycles and aerobic metabolism.
muscle rupture
the muscle may have torn away from its insertion, in which case the tendon will be slack, or it may be a complete or partial separation of the belly of the muscle, when the muscle will be swollen and hard. Structural and conformational changes may result, e.g. in rupture of the gastrocnemius muscle, and the hernias caused by rupture of the ventral abdominal muscles or the diaphragm.
skeletal m's
striated muscles that are attached to bones and typically cross at least one joint. Called also voluntary or striated muscles.
slow-twitch skeletal muscle
type 1 skeletal muscle fibers are bright red and contain large amounts of myoglobin; not easily fatigued.
smooth muscle
plain or involuntary muscle which powers the internal organs and is controlled by the autonomic nervous system; slow contracting cycles and fatigue resistant. Two types listed, visceral and vascular.
sphincter muscle
a ringlike muscle that closes a natural orifice; called also sphincter.
muscle spindle
sensory end-organ attached to the perimysial connective tissue of the muscle.
muscle strain
soreness and stiffness in a muscle due to overexertion or contusion, especially in muscles that have not been conditioned for hard use; some of the muscle fibers may actually tear.
striated muscle
see skeletal muscles (above).
synergic m's
those that assist one another in action.
temporal muscle
a significant muscle of mastication. See also Table 13.1H.
muscle-tendon junction
the union between connective tissue investing muscles and anchoring connective tissue.
type I muscle fiber
see slow-twitch skeletal muscle (above).
type II muscle fiber
see fast-twitch skeletal muscle (above).
type II muscle fiber deficiency
a relative deficiency of type II muscle fibers, with a predominance of type I fibers. An inherited defect in Labrador retrievers. Clinical signs include stunted growth, and muscle weakness and abnormal gait, which subside with rest, from an early age.
voluntary muscle
see skeletal muscle (above).
white muscle
consist of type II fibers; fast contraction fibers and aerobic metabolism are characteristic.
yoked m's
those that normally act simultaneously and equally, as in moving the eyes.
References in periodicals archive ?
Data collected permit an analysis of how pink and red muscle are used during steady swimming in scup over a range of speeds.
The placement of electrodes into either the thin pink layer or the overlying red muscle was verified through dissection after each experiment.
Positive values indicate that the activity of red muscle occurred before that of pink muscle; negative values indicate that pink muscle activity had an earlier onset.
At the MID position, red muscle and pink muscle were initially recruited at the lowest steady swimming speed, 2.
The stimulation of red muscle during each tailbeat cycle occurred at the same time as or just prior to stimulation of pink muscle for most swimming conditions at 20 [degrees] C ([ILLUSTRATION FOR FIGURE 4 OMITTED], Table III).
Red muscle had longer duty cycles than pink muscle.
Whereas red muscle is active at most positions at all swimming speeds, pink muscle activity is restricted on the basis of both longitudinal position and swimming speed.
Initial recruitment of pink muscle occurs at swimming speeds the same as or higher than recruitment speed of red muscle for all longitudinal positions.
At the lowest steady swimming speed, red muscle was active at the POST (Rome, unpubl.
A recent report on muscle function in swimming eels (Gillis, 1998) describes a pattern of recruitment for red muscle similar to that in scup.
For most swimming speeds and at most positions, the duty cycle of red muscle is longer than that of pink muscle.