n. any muscle that causes the straightening of a limb or other part.
– although lead-containing paints are no longer used for items that children may be in contact with.
Acute poisonings are rare. Clinical features include metallic taste, abdominal pain, vomiting, diarrhoea, ANOREXIA, fatigue, muscle weakness and SHOCK. Neurological effects may include headache, drowsiness, CONVULSIONS and COMA. Inhalation results in severe respiratory-tract irritation and systemic symptoms as above.
Chronic poisonings cause gastrointestinal disturbances and constipation. Other effects are ANAEMIA, weakness, pallor, anorexia, insomnia, renal HYPERTENSION and mental fatigue. There may be a bluish ‘lead line’ on the gums, although this is rarely seen. Neuromuscular dysfunction may result in motor weakness and paralysis of the extensor muscles of the wrist and ankles. ENCEPHALOPATHY and nephropathy are severe effects. Chronic low-level exposures in children are linked with reduced intelligence and behavioural and learning disorders.
Treatment Management of patients who have been poisoned is supportive, with removal from source, gastric decontamination if required, and X-RAYS to monitor the passage of metallic lead through the gut if ingested. It is essential to ensure adequate hydration and renal function. Concentrations of lead in the blood should be monitored; where these are found to be toxic, chelation therapy should be started. Several CHELATING AGENTS are now available, such as DMSA (Meso-2,3dimercaptosuccinic acid), sodium calcium edetate (see EDTA) and PENICILLAMINE. (See also POISONS.)... lead poisoning
There are more than 600 muscles in the body, classified according to the type of movement they produce.
An extensor opens out a joint, a flexor closes it; an adductor draws a part of the body inwards, an abductor moves it outwards; a levator raises it, a depressor lowers it; and constrictor or sphincter muscles surround and close orifices.... muscular system
Structure of muscle Skeletal or voluntary muscle forms the bulk of the body’s musculature and contains more than 600 such muscles. They are classi?ed according to their methods of action. A ?exor muscle closes a joint, an extensor opens it; an abductor moves a body part outwards, an adductor moves it in; a depressor lowers a body part and an elevator raises it; while a constrictor (sphincter) muscle surrounds an ori?ce, closing and opening it. Each muscle is enclosed in a sheath of ?brous tissue, known as fascia or epimysium, and, from this, partitions of ?brous tissue, known as perimysium, run into the substance of the muscle, dividing it up into small bundles. Each of these bundles consists in turn of a collection of ?bres, which form the units of the muscle. Each ?bre is about 50 micrometres in thickness and ranges in length from a few millimetres to 300 millimetres. If the ?bre is cut across and examined under a high-powered microscope, it is seen to be further divided into ?brils. Each ?bre is enclosed in an elastic sheath of its own, which allows it to lengthen and shorten, and is known as the sarcolemma. Within the sarcolemma lie numerous nuclei belonging to the muscle ?bre, which was originally developed from a simple cell. To the sarcolemma, at either end, is attached a minute bundle of connective-tissue ?bres which unites the muscle ?bre to its neighbours, or to one of the connective-tissue partitions in the muscle, and by means of these connections the ?bre affects muscle contraction. Between the muscle ?bres, and enveloped in a sheath of connective tissue, lie here and there special structures known as muscle-spindles. Each of these contains thin muscle ?bres, numerous nuclei, and the endings of sensory nerves. (See TOUCH.) The heart muscle comprises short ?bres which communicate with their neighbours via short branches and have no sarcolemma.
Plain or unstriped muscle is found in the following positions: the inner and middle coats of the STOMACH and INTESTINE; the ureters (see URETER) and URINARY BLADDER; the TRACHEA and bronchial tubes; the ducts of glands; the GALL-BLADDER; the UTERUS and FALLOPIAN TUBES; the middle coat of the blood and lymph vessels; the iris and ciliary muscle of the EYE; the dartos muscle of the SCROTUM; and in association with the various glands and hairs in the SKIN. The ?bres are very much smaller than those of striped muscle, although they vary greatly in size. Each has one or more oval nuclei and a delicate sheath of sarcolemma enveloping it. The ?bres are grouped in bundles, much as are the striped ?bres, but they adhere to one another by cement material, not by the tendon bundles found in voluntary muscle.
Development of muscle All the muscles of the developing individual arise from the central layer (mesoderm) of the EMBRYO, each ?bre taking origin from a single cell. Later on in life, muscles have the power both of increasing in size – as the result of use, for example, in athletes – and also of healing, after parts of them have been destroyed by injury. An example of the great extent to which unstriped muscle can develop to meet the demands made on it is the uterus, whose muscular wall develops so much during pregnancy that the organ increases from the weight of 30–40 g (1–1••• oz.) to a weight of around 1 kg (2 lb.), decreasing again to its former small size in the course of a month after childbirth.
Physiology of contraction A muscle is an elaborate chemico-physical system for producing heat and mechanical work. The total energy liberated by a contracting muscle can be exactly measured. From 25–30 per cent of the total energy expended is used in mechanical work. The heat of contracting muscle makes an important contribution to the maintenance of the heat of the body. (See also MYOGLOBIN.)
The energy of muscular contraction is derived from a complicated series of chemical reactions. Complex substances are broken down and built up again, supplying each other with energy for this purpose. The ?rst reaction is the breakdown of adenyl-pyrophosphate into phosphoric acid and adenylic acid (derived from nucleic acid); this supplies the immediate energy for contraction. Next phosphocreatine breaks down into creatine and phosphoric acid, giving energy for the resynthesis of adenyl-pyrophosphate. Creatine is a normal nitrogenous constituent of muscle. Then glycogen through the intermediary stage of sugar bound to phosphate breaks down into lactic acid to supply energy for the resynthesis of phosphocreatine. Finally part of the lactic acid is oxidised to supply energy for building up the rest of the lactic acid into glycogen again. If there is not enough oxygen, lactic acid accumulates and fatigue results.
All of the chemical changes are mediated by the action of several enzymes (see ENZYME).
Involuntary muscle has several peculiarities of contraction. In the heart, rhythmicality is an important feature – one beat appearing to be, in a sense, the cause of the next beat. Tonus is a character of all muscle, but particularly of unstriped muscle in some localities, as in the walls of arteries.
Fatigue occurs when a muscle is made to act for some time and is due to the accumulation of waste products, especially sarcolactic acid (see LACTIC ACID). These substances affect the end-plates of the nerve controlling the muscle, and so prevent destructive overaction of the muscle. As they are rapidly swept away by the blood, the muscle, after a rest (and particularly if the rest is accompanied by massage or by gentle contractions to quicken the circulation) recovers rapidly from the fatigue. Muscular activity over the whole body causes prolonged fatigue which is remedied by rest to allow for metabolic balance to be re-established.... muscle
– an early graded return to activity gives the best long-term results, but doing too much too soon runs the risk of exacerbating the original injury.
Chronic (overuse) injuries affecting the bones (see BONE), tendons (see TENDON) or BURSAE of the JOINTS are common in many sports. Examples include chronic INFLAMMATION of the common extensor tendon where it
attaches to the later EPICONDYLE of the humerus – common in throwers and racquet sportspeople – and stress fractures of the TIBIA or METATARSAL BONES of the foot in runners. After an initial period of rest, management often involves coaching that enables the athlete to perform the repetitive movement in a less injury-susceptible manner.
Exercise physiology is the science of measuring athletic performance and physical ?tness for exercise. This knowledge is applied to devising and supervising training regimens based on scienti?c principles. Physical ?tness depends upon the rate at which the body can deliver oxygen to the muscles, known as the VO2max, which is technically di?cult to measure. The PULSE rate during and after a bout of exercise serves as a good proxy of this measurement.
Regulation of sport Sports medicine’s role is to minimise hazards for participants by, for example, framing rule-changes which forbid collapsing the scrum, which has reduced the risk of neck injury in rugby; and in the detection of the use of drugs taken to enhance athletic performance. Such attempts to gain an edge in competition undermine the sporting ideal and are banned by leading sports regulatory bodies. The Olympic Movement Anti-Doping Code lists prohibited substances and methods that could be used to enhance performance. These include some prohibited in certain circumstances as well as those completely banned. The latter include:
stimulants such as AMPHETAMINES, bromantan, ca?eine, carphedon, COCAINE, EPHEDRINE and certain beta-2 agonists.
NARCOTICS such as DIAMORPHINE (heroin), MORPHINE, METHADONE HYDROCHLORIDE and PETHIDINE HYDROCHLORIDE.
ANABOLIC STEROIDS such as methandione, NANDROLONE, stanazol, TESTOSTERONE, clenbuterol, androstenedone and certain beta-2 agonists.
peptide HORMONES, mimetics and analogues such as GROWTH HORMONE, CORTICOTROPHIN, CHORIONIC GONADOTROPHIC HORMONE, pituitary and synthetic GONADOTROPHINS, ERYTHROPOIETIN and INSULIN. (The list produced above is not comprehen
sive: full details are available from the governing bodies of relevant sports.) Among banned methods are blood doping (pre-competition administration of an athlete’s own previously provided and stored blood), administration of arti?cial oxygen carriers or plasma expanders. Also forbidden is any pharmacological, chemical or physical manipulation to affect the results of authorised testing.
Drug use can be detected by analysis of the URINE, but testing only at the time of competition is unlikely to detect drug use designed to enhance early-season training; hence random testing of competitive athletes is also used.
The increasing professionalism and competitiveness (among amateurs and juveniles as well as professionals) in sports sometimes results in pressures on participants to get ?t quickly after injury or illness. This can lead to
players returning to their activity before they are properly ?t – sometimes by using physical or pharmaceutical aids. This practice can adversely affect their long-term physical capabilities and perhaps their general health.... sports medicine
Atopic eczema. Allergic eczema. May run in families together with hay fever, asthma or inflamed nasal membrane. May appear anywhere but prefers elbows, knees (flexures), ankles or face. Often seen in infants. May return again and again throughout adult life. Scratching exacerbates.
As regards babies, some paediatricians believe breast-feeding to be protective. A stronger case follows investigation into pollutants from the atmosphere or as additives in food. Industrial chemicals find their way into breast milk that may not be easily excreted but stored in fat.
Cow’s milk is particularly suspect because of exposure of the animal to herbicides and pesticides. For this reason, goat’s milk has met with some success in treatment of this condition, as has Soya milk. Now known that food plays an important part in effective treatment. Chief allergy-stimulators: dairy produce, eggs, cow’s milk. Each individual case must identify those foods that are responsible.
Seborrhoeic eczema leads to scaling of the scalp and redness of the ears, eyebrows, side of the nose and possibly armpits and groin.
Stasis eczema (or varicose eczema) may arise from varicose vein problems, usually limited to the lower third of the leg.
Discoid eczema has coin-shaped patches preferring extensor surfaces of arms and legs.
Contact eczema may be caused by washing-up detergents, etc. See: CONTACT DERMATITIS.
While emotional or psychic disturbance may worsen, eczema is seldom a psychosomatic disorder arising from stressful situations. Contact with water may worsen. Hairdressers and those allergic to dyes may require patch tests.
Eczema patients, especially atopic, have a metabolic deficiency of linoleic acid (a dietary fatty acid) to y-linolenic acid, which is found in Evening Primrose oil. Eczema may develop in bottle-fed babies due to absence of GLA (gamma-linolenic acid) in commercial powdered milk. GLA is present in Evening Primrose.
A cross-over trial in 99 patients (adults and children) by Bristol (England) dermatologists found Evening Primrose oil (Efamol capsules) produced an overall 43 per cent improvement in eczema severity: doses – 4 to 6 capsules twice daily (adults); 2 capsules twice daily (children). Lower doses were not effective.
Alternatives. Barberry, Bladderwrack, Blood root, Blue Flag root, Bogbean, Burdock, Clivers, Devil’s Claw, Echinacea, Figwort, Fringe Tree, Fumitory, Garlic, Guaiacum, Goldenseal, Mountain Grape, Gotu Kola, Nettles, Plantain, Poke root, Queen’s Delight, Red Clover, Sarsaparilla, Sassafras, Wild Indigo, Heartsease, Yellow Dock.
Tea. Combine herbs: equal parts: Gotu Kola, Clivers, Red Clover. 1-2 teaspoons to each cup boiling water; infuse 5-10 minutes; 1 cup thrice daily, before meals (Dry eczema).
Formula: equal parts, Burdock root, Yellow Dock root, Valerian root. Dose. Liquid Extracts, 1 teaspoon. Tinctures, 1-2 teaspoons. Powders, two 00 capsules or one-third teaspoon. Thrice daily, before meals. Practitioner: specific medication.
Dry eczema. Equal parts, tinctures: Yarrow, Dandelion, Calendula, Echinacea.
Weeping eczema. Combine tinctures: Barberry 1; Clivers 2; Echinacea 2.
Seborrhoeic eczema. Combine tinctures: Blue Flag root 1; Meadowsweet 2; Boneset 1.
Discoid eczema. Combine tinctures: Yellow Dock 2; Mountain Grape 1; Echinacea 1.
Varicose eczema. Combine tinctures: Echinacea 2; Calendula (Marigold) 1; Hawthorn 1.
Dosage for the above: One to two 5ml teaspoons in water thrice daily before meals.
Skin Care. May reduce necessity for steroid creams. It is best to avoid: lanolin and Coconut oil compounds that may contain coal tar. Wash in soft water (rain water) or water not containing chemical softeners.
Indicated: soothing softening herbal lotions, ointments or creams: Marshmallow, Chickweed, Comfrey, Witch Hazel, Aloe Vera gel, Jojoba oil, Evening Primrose oil. For seborrhoeic eczema: Bran Bath or Bran Wash, twice weekly, soapless, followed by Rosemary shampoo. Vitamin E lotion or cream.
Note: A study carried out at the University of Manchester, England, found that children with eczema had significantly low levels of serum zinc than control-cases. (British Journal of Dermatology, 1984, 111, 597)
Evening Primrose oil. For Omega 6 fatty acids.
Diet. Gluten-free. Oily fish: see entry. Avoid cow’s milk, wheat products.
Supplements. Daily. Vitamins: A (7500iu). C (500mg). E (400iu). Bioflavonoids (500mg). Zinc (15mg). Betaine hydrochloride.
Note: The disorder may be due to a deficiency of essential fatty acids (EFAs) brought about by a deficiency of zinc which is necessary for EFA metabolism.
Chinese herbs. A study has shown herbal treatment to be far superior to placebo in clinical trials. British children with (dry) atopic eczema responded favourably to treatment which included the following herbs known as Formula PSE101.
Ledebouriella sesloides, Potentilla chinesis, Anebia clematidis, Rehmannia glutinosa, Peonia lactiflora, Lophatherum gracile, Dictamnus dasycarpus, Tribulus terrestris, Glycyrrhiza uralensis, Schizonepta tenuifolia. Non-toxicity confirms their safety. (Sheeham M et al. “A controlled trial of traditional Chinese medicinal plants in widespread non-exudative atopic dermatitis”, British Journal of Dermatology, 126: 179-184 1992)
When 10 Chinese herbs were analysed by a team at the Great Ormond Street Hospital, London, it was revealed that no single active ingredient or herb was responsible for success. “It was a combination of all 10 herbs that gave the medicine its healing properties.” This is an example of the synergistic effect of combined plant remedies and supports the herbalist’s belief in use of the whole plant. ... eczema
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