Muscle

Muscle is a contractile form of tissue. It is one of the four major tissue types, the other three being epithelium, connective tissue and nervous tissue. Muscle contraction is used to move parts of the body, as well as to move substances within the body.

Role in health and disease

Exercise

Exercise is often recommended as a means of improving motor skills, fitness and muscle strength. Exercise has several effects upon muscles, connective tissue and bone, and the nerves that stimulate the muscles.

Related Topics:
Exercise - Motor skill - Fitness - Bone

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Disease

Symptoms of muscle disease may include weakness or spasticity/rigidity, myoclonus (twitching) and myalgia (muscle pain). Diagnostic procedures that may reveal muscular disorders include testing creatine kinase levels in the blood and electromyography (measuring electrical activity in muscles).

Related Topics:
Weakness - Spasticity - Myoclonus - Myalgia - Creatine kinase - Electromyography

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Neuromuscular diseases are those that affect the muscles and/or their nervous control. In general, problems with nervous control can cause spasticity or paralysis, depending on the location and nature of the problem. A large proportion of neurological disorders leads to problems with movement, ranging from cerebrovascular accident (stroke) and Parkinson's disease to Creutzfeldt-Jakob disease.

Related Topics:
Neuromuscular disease - Spasticity - Paralysis - Cerebrovascular accident - Parkinson's disease - Creutzfeldt-Jakob disease

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Diseases of the motor end plate include myasthenia gravis, a form of muscle weakness due to antibodies to the acetylcholine receptor, and its related condition Lambert-Eaton myasthenic syndrome (LEMS). Tetanus and botulism are bacterial infections in which bacterial toxins cause increased or decreased muscle tone, respectively.

Related Topics:
Myasthenia gravis - Antibodies - Acetylcholine - Lambert-Eaton myasthenic syndrome - Tetanus - Botulism

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The myopathies are all diseases affecting the muscle itself, rather than its nervous control.

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Muscular dystrophy is a large group of diseases, many of them hereditary, where the muscle integrity is disrupted. It leads to progressive loss of strength, high dependence and decreased life span.

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Inflammatory muscle disorders:

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• Polymyalgia rheumatica (or "muscle rheumatism") is an inflammatory condition that mainly occurs in the elderly; it is associated with giant-cell arteritis. It often responds dramatically to glucocorticoids (e.g. prednisolone).
• Polymyositis, dermatomyositis and inclusion-body myositis are autoimmune conditions in which the muscle is affected.

Rhabdomyolysis is the breakdown of muscular tissue due to any cause. While it may not lead to any muscular symptoms at all, the myoglobin thus released may cause acute renal failure.

Related Topics:
Rhabdomyolysis - Myoglobin - Acute renal failure

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Tumors of muscle include:

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• Smooth muscle: leiomyoma (benign, very common in the uterus), leiomyosarcoma (malignant, very rare)
• Striated muscle: rhabdomyoma (benign) and rhabdomyosarcoma (malignant) - both very rare
• Metastasis from elsewhere (e.g. lung cancer)

Smooth muscle has been implicated to play a role in a large number of diseases affecting blood vessels, the respiratory tract (e.g. asthma), the digestive system (e.g. irritable bowel syndrome) and the urinary tract (e.g. urinary incontinence). These disease processes are not usually confined to the muscular tissue.

Related Topics:
Blood vessel - Respiratory tract - Asthma - Digestive system - Irritable bowel syndrome - Urinary tract - Urinary incontinence

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