Page:The New International Encyclopædia 1st ed. v. 02.djvu/104

ARTEMISIA. stomachic, and are also used in anodyne fomentations. Moxa (q.v.) is prepared by the Chinese from the leaves of Artemisia moxa and other species, the whole surface of whose leaves is covered with a thick down. In the western United States many shrubby species exist and are known as 'sage brush.' One of the most common is Artemisia tridentata, with small, wedge-shaped leaves, three to seven-notched. These plants are important forage for cattle and sheep, especially the latter. See.

ARTEMISIA (Gk. Ἀρτεμισία) (c. 350 B.C.). A queen of Caria. She was the wife of Mausolus, and is celebrated for the magnificent monument which she caused to be erected to her husband's memory. (See .) Another Artemisia, a queen of Halicarnassus in Caria, and a vassal of the Persian King, joined the fleet of Xerxes in the expedition against Greece, and distinguished herself by bravery and skill at the battle of Salamis (B.C. 480). The Athenians, indignant that a woman should appear in arms against them, offered a reward of 10,000 drachms for her capture, but she escaped. According to a doubtful tradition, Artemisia afterwards jumped from the Leucadian Rock, in consequence of a disappointment in love.

ARTEMISIUM, ar'tc-mlsh'i-um (Gk. Ἀρτεμίσιον, Artemision). — (1) The stretch of coast at the northern extremity of Eubœa, opposite the Thessalian Magnesia. It belonged to the town of Histiæa, and was named from the temple of Artemis, which stood here. Off this point occurred the first naval conflict between the Greeks and the Persians at the time of the invasion of Xerxes. — (2) A mountain between Argolis and Arcadia, now called Malewo. On the summit was a temple of Artemis. — (3) A promontory and temple of Artemis in Caria.

AR'TERIES, See.

ARTE'RIO-SCLERO'SIS (Gk. ἀρτηρία, artēria, artery + σκλήρωσις, sklērōsis, induration). A disease of the arteries, resulting in hardening of the muscular elastic coat. The connective tissue of the walls is increased in quantity. This produces a contraction, by pressure, on the blood-vessels supplying the artery, which in turn causes weakening and degeneration of the walls of the vessel. It loses its elasticity, becomes hard and rigid, and is easily ruptured. If the degeneration takes place in spots or mainly involves one of the arterial coats, with the production of fatty degeneration and subsequent deposit of lime salts in the walls of the vessel, it is termed atheromatous, from atheroma (Greek athērē, meal), the name of the fatty or chalky substance. At times the increase in the amount of connective tissue is so great that the lumen of the blood vessels is obliterated. The causes of arteriosclerosis are chronic alcoholism, gout, lead-poisoning, syphilis, deficient metabolism from habitual overeating, overwork of the heart, and kidney diseases. See.

AR'TERY (Lat. arteria, Gk. ἀρτηρία, artēria, wind-pipe, artery). An anatomical term designating any one of the vessels through which the blood passes from the left side of the heart to the tissues, named from the old idea that these tubes were air-carriers because they are empty after death. The structure of an arterial tube is very complex, and a section of it may be roughly subdivided into three layers, called the coats of the artery: an external, which is elastic and distensible, the tunica adventitia; a middle, which is muscular, contractile, and brittle, the tunica media; an internal, also brittle, smooth, and transparent, being lined within by endothelium, the tunica intima. The tube is also enveloped in cellular tissue, termed the sheath of the artery. When an artery is wounded by a sharp instrument, the effect varies with the direction of the cut. Thus, if longitudinal, the edges may not separate, and the wound may heal without much bleeding; if oblique or transverse the edges gape, and a nearly circular orifice allows of a profuse hemorrhage. If the artery be completely divided, its walls do not collapse like those of a vein, but pass through certain changes provided by nature to limit hemorrhage. The cut orifice contracts, and also retracts into its cellular sheath; this checks the flow of blood, a clot of which shortly forms on the outer side; then another forms inside the vessel, and together they stem the flow till the cut edges of the artery have time to throw out lymph (see ), and heal as wounds of other tissues. When an artery is compressed by a ligature, the brittle inner and middle coats crack, curl inwards, and unite. See.

SUBDIVISIONS OF ARTERIAL WALLS. 1. Enduthelial layer. 2. Fenestrated membrane. y. Muscular layer. 4. Elastic layer. 5, Fibro-connective layer. 6. Areolar sheath.

The arteries of the human body are all offsets, more or less direct, of the aorta. As each main trunk passes into a portion of the body, it divides into two principal divisions: one, which breaks up into branches for the supply of the tissues in the vicinity — the artery of supply; and another, which passes almost branchless to supply the parts beyond — the artery of transmission. These, however, anastomose freely, so that the distant tissues are not solely dependent for their supply on only one arterial trunk. Thus, the femoral artery divides in the groin into the profunda, or deep femoral, to supply the thigh, and the superficial femoral, to supply the leg below the knee. Again, the common carotid divides into external carotid, to supply the neck and head, and the internal carotid to supply the brain, although arteries have generally the same distribution or arrangement of branches, they occasionally vary, and may in this way be misleading to the student or the surgeon. Comparative anatomy goes far to explain these apparent discrepancies in arterial distribution.