Also called a stretch-mark, a line on the skin caused by thinning and loss of elasticity in the dermis. Striae first appear as red, raised lines. Later they become purple, eventually fading to shiny streaks.
Striae often develop on the hips and thighs during the adolescent growth spurt, especially in athletic girls. They are a common feature of pregnancy, occurring on the breasts, thighs, and lower abdomen. Purple striae are a characteristic feature of Cushing’s syndrome.
Striae are thought to be caused by an excess of corticosteroid hormones.
There is no means of prevention, but in some cases laser treatment may be used.
n. (pl. striae) (in anatomy) a streak, line, or thin band. The striae gravidarum (stretch marks) are the lines that appear on the skin of the abdomen of pregnant women, due to excessive stretching of the elastic fibres. Red or purple during pregnancy, they become white after delivery. The stria terminalis is a white band that separates the thalamus from the ventricular surface of the caudate nucleus in the brain.
Stretch-marks seen in the skin, common in adolescent boys and girls owing to stretching of the skin by rapid growth (striae distensae). In boys, striae occur around the shoulders and thighs; in girls the breasts and hips are affected. In both sexes horizontal striae on the back may be mistaken for signs of trauma. Striae are common in women in late pregnancy, especially on the lower abdomen (striae gravidarum). Injudicious prolonged use of potent topical CORTICOSTEROIDS can induce striae, particularly about the groins, inner thighs or armpits. Prolonged high-dose oral STEROID therapy may cause widespread striae.... striae
a tissue comprising the bulk of the body’s musculature. It is also known as skeletal muscle, because it is attached to the skeleton and is responsible for the movement of bones, and voluntary muscle, because it is under voluntary control. Striated muscle is composed of parallel bundles of multinucleate fibres (each containing many myofibrils), which reveal cross-banding when viewed under the microscope. This effect is caused by the alternation of actin and myosin protein filaments within each myofibril (see illustration). According to the ‘sliding filament’ theory, when muscle contraction takes place, the two sets of filaments slide past each other, so reducing the length of each unit (sarcomere) of the myofibril. The sliding is caused by a series of cyclic reactions, requiring ATP, resulting in a change in orientation of projections on the myosin filaments; each projection is first attached to an actin filament but contracts and releases it to become reattached at a different site.... striated muscle
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