| Muller's muscle | <anatomy> A rudimentary nonstriated muscle, crossing the infraorbital groove and sphenomaxillary fissure, intimately united with the periosteum of the orbit. Synonym: musculus orbitalis, Muller's muscle, orbital muscle. (05 Mar 2000) |
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| pleuroesophageal muscle | <anatomy> Muscular fasciculi, arising from the mediastinal pleura, which reinforce musculature of oesophagus. Synonym: musculus pleuroesophageus. (05 Mar 2000) |
| multipennate muscle | <anatomy> A muscle with several central tendons toward which the muscle fibres converge like the barbs of feathers. Synonym: musculus multipennatus. (05 Mar 2000) |
| wrinkler muscle of eyebrow | <anatomy, muscle> Origin, from orbital portion of musculus orbicularis oculi and nasal prominence; insertion, skin of eyebrow; action, draws medial end of eyebrow downward and wrinkles forehead vertically; nerve supply, facial. Synonym: musculus corrugator supercilii, Coiter's muscle, corrugator muscle, wrinkler muscle of eyebrow. (05 Mar 2000) |
| muscle | <anatomy> Tissue specialised for contraction. See twitch muscle, catch muscle: Cardiac muscle (heart muscle) is a striated but involuntary muscle responsible for the pumping activity of the vertebrate heart. The individual muscle cells are joined through a junctional complex known as the intercalated disc and are not fused together into multinucleate structures as they are in skeletal muscle. Skeletal muscle is a rather non-specific term usually applied to the striated muscle of vertebrates that is under voluntary control. The muscle fibres are syncytial and contain myofibrils, tandem arrays of sarcomeres. Smooth muscle is muscle tissue in vertebrates made up from long tapering cells that may be anything from 20-500m long. Smooth muscle is generally involuntary and differs from striated muscle in the much higher actin/myosin ratio, the absence of conspicuous sarcomeres and the ability to contract to a much smaller fraction of its resting length. Smooth muscle cells are found particularly in blood vessel walls, surrounding the intestine (especially the gizzard in birds) and in the uterus. The contractile system and its control resemble those of motile tissue cells (for example fibroblasts, leucocytes) and antibodies against smooth muscle myosin will cross react with myosin from tissue cells, whereas antibodies against skeletal muscle myosin will not. See: dense bodies. (18 Nov 1997) |
| muscle, adductor | Any muscle that pulls inward toward the midline of the body. For example, the adductor muscles of the leg serve to pull the legs together. The opposite of adductor is abductor. To keep these similar sounding terms straight, medical students learn to speak of a b ductors versus a d ductors. (12 Dec 1998) |
| muscle biopsy | <investigation, procedure, surgery> A procedure which involves the removal of a small specimen of muscle tissue for microscopic analysis. A muscle biopsy is used to distinguish between neurological and myopathic (muscle disease) disorders, identify muscular dystrophy, diagnose muscle infections and identify connective tissue disorders (necrotising vasculitis). (21 Mar 1998) |
| muscle-bound | Denoting a condition in which individual muscles are overdeveloped but dyssynergic in concerted action. (05 Mar 2000) |
| muscle bundle | A group of muscle fibres ensheathed by connective tissue (perimysium). (05 Mar 2000) |
| muscle cell | <cell biology, pathology> Cell of muscle tissue, in striated (skeletal) muscle it comprises a syncytium formed by the fusion of embryonic myoblasts, in cardiac muscle a cell linked to the others by specialise d junctional complexes (intercalated discs), in smooth muscle a single cell with large amounts of actin and myosin capable of contracting to a small fraction of its resting length. (07 Apr 1998) |
| muscle, central core disease of | One of the conditions that produces 'floppy baby' syndrome. Ccd causes hypotonia (inadequately toned muscles characterised by floppiness) in the newborn baby, slowly progressive muscle weakness, and muscle cramps after exercise. Muscle biopsy shows a key diagnostic finding (absent mitochondria in the centre of many type i muscle fibres). Ccd is inherited as a dominant trait. The ccd gene is on chromosome 19 (and involves ryanodine receptor-1). (12 Dec 1998) |
| muscle contraction | A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments. (12 Dec 1998) |
| muscle curve | <investigation, physiology> A test which measures muscle response to nerve stimulation. Used to evaluate muscle weakness and to determine if the weakness is related to the muscles themselves or a problem with the nerves that supply the muscles. Abnormal results may be seen in myasthenia gravis, polymyositis, carpal tunnel syndrome, amyotrophic lateral sclerosis, alcoholic neuropathy, cervical spondylosis, dermatomyositis, familial periodic paralysis, Guillain-Barre syndrome, Lambert-Eaton syndrome, Friedreich's ataxia, mononeuritis multiplex, peripheral neuropathy, sciatic nerve disease and a variety of peripheral nerve disorders. (27 Sep 1997) |
| muscle denervation | The resection or removal of the innervation of a muscle or muscle tissue. (12 Dec 1998) |
| muscle epithelium | Spindle-shaped, contractile, smooth muscle-like cells of epithelial origin that are arranged longitudinally or obliquely around sweat glands and the secretory alveoli of the mammary gland; stellate myoepithelial cells occur around lacrimal and some salivary gland secretory units. Synonym: muscle epithelium. Origin: myo-+ epithelium (05 Mar 2000) |