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a condition in which a muscle loses its ability to contract as a result of overactivity. It is usually a period after stimulation during which the muscle is unresponsive to a second stimulus.
1. pertaining to a muscle.
2. having well developed muscles.
due usually to neuronal or disuse atrophy on one side of the body.
wasting away of muscle or a muscle because of reduction in cross sectional area of muscle fibers; may be due to disease of the muscle or its nerve supply, or to disuse or nutritional inadequacy. See also hereditary spinal muscular atrophy (below).
varies in severity from degeneration of only the myofibrils or degeneration of the myofibrils plus sarcoplasm, leaving satellite cells and myonuclei and sarcolemmal laminae unaffected, or further levels of increasing severity.
destruction or congenital absence of the motor nerve supply to the muscle; manifested by paralysis and atrophy and absence of spinal reflexes.
muscular denervation atrophy
progressive shrinkage of muscle fibers when the nerve supply to the muscle is severed.
Duchenne muscular dystrophy
an X-linked inherited disease in humans, which is believed to be due to a deficiency of a membrane-associated protein, dystrophin. An analogous disease has been identified in Irish terriers, Golden retrievers and mice.
any degenerative muscular disorder due to faulty nutrition of the muscles. Causes muscle weakness, liberation of myoglobin into the circulation from skeletal muscle and subsequent wasting and possible contracture. In humans there are a group of genetically determined, painless, degenerative myopathies that are progressively crippling because muscles are gradually weakened and eventually atrophy. In food animals the principal disease in this group is enzootic muscular dystrophy caused by a nutritional deficiency of selenium and/or vitamin E. Sporadic cases of muscular dystrophy of unknown etiology occur rarely in dogs.
during brief, intense exercise probably due in large part to the accumulation of lactate.
hereditary spinal muscular atrophy
progressive degeneration of the motor cells of the spinal cord. It is an inherited, slowly progressive flaccid tetraparesis from an early age, with muscular atrophy. Occurs as an autosomal recessive trait in Swedish lapland dogs, a dominant trait in Brittany spaniels. Also reported in German shepherd dogs, English pointers and Rottweilers. See also hereditary neuronal abiotrophy of Swedish Lapland dogs. In cattle, inherited as an autosomal recessive trait and reported in Brown Swiss, Holstein-Friesian and Red Danish calves with an onset at 3 to 8 weeks of age. There is hind limb ataxia progressing to recumbancy. Associated with lesions in the lower motor neurons of the cervical and lumbar spinal cord.
hernia through an enclosing muscle sheath.
an increase in the size of a muscle mass due to an increase in the number of muscle cells. See also myofiber hyperplasia, ileal muscular hypertrophy.
an increase in the size of a muscle mass due to an increase in the length and thickness of each muscle cell without any increase in the number of cells.
muscular ischemic necrosis
see ischemic myonecrosis.
ectopic deposition of minerals in muscle. See mineralization.
myelopathic muscular atrophy
muscular atrophy due to a lesion of the spinal cord, as in spinal muscular atrophy.
nutritional muscular dystrophy
see muscular dystrophy (above).
muscular parasitic diseases
includes cysticercosis, hepatozoonosis, Neosprum caninum myositis, sarcocystosis, toxoplasmosis, trichenellosis.
muscle spindles which respond to stretch.
excess fat deposits in muscle; a problem only at meat hygiene inspection.
muscular vascular occlusive syndrome
see ischemic myonecrosis.
X-linked muscular dystrophy
see Duchenne muscular dystrophy (above).