Muscles and Bones Dictionary

lipid storage disorders: A group of inherited metabolic disorders in which harmful amounts of lipids, or fats, accumulate in some of the body’s cells and tissues. Victims of this disorder fail to produce enough of one of the enzymes needed to metabolize lipids or they produce enzymes that do not work properly.

limb-girdle muscular dystrophy: An autosomal class of muscular dystrophy that is similar but distinct from Duchenne and Becker’s muscular dystrophy. It affects muscles of the hips and the shoulders or limb-girdle muscles.

mitochondria: Cellular structures that control energy.

mitochondrial myopathies: A type of myopathy caused by genetic abnormalities in mitochondria.

muscular dystrophies: A group of genetic and hereditary muscle diseases characterized by progressive weakness in voluntary muscles, which is sometimes evident at birth.

myoglobinurias: A myopathy caused by disorders in the metabolism of a fuel (myoglobin) necessary for muscle work.

myopathy: A neuromuscular disorder in which the primary symptom is muscle weakness due to dysfunction of muscle fiber. Symptoms include muscle cramps, stiffness and spasms.

myositis ossificans: A myopathy characterized by bone growing in muscle tissue.

myotonia: A symptom of certain neuromuscular disorders characterized by the slow relaxation of the muscles after voluntary contraction or electrical stimulation.

myotonic dystrophy: A chronic, slowly progressing, highly variable inherited multisystemic disease that can manifest at any age. It is characterized by wasting of the muscles, posterior subcapsular iridescent cataracts, heart conduction defects, endocrine changes and myotonia.

nemaline myopathy: A group of congenital and hereditary neuromuscular disorders that cause muscle weakness of varying severity.

nemaline rod myopathy: An autosomal dominant or recessive genetic disease characterized by infantile muscle weakness, loss of muscle tone and the presence of nemaline rods in the muscle. It is usually accompanied by problems in suckling or feeding, a delay in walking and occasionally respiratory problems.

neuromyotonia: Spontaneous muscular activity such as alternating episodes of twitching and stiffness resulting from repetitive motor unit action potentials of peripheral origin.