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 erected a monument, or trophy, in Rhodes, to commemorate her conquest of that island. When the Rhodians regained their freedom they built round this trophy so as to render it inaccessible, whence it was known as the Abaton. There are statues of Mausolus and Artemisia in the British Museum.

Vitruvius ii. 8; Diodorus Siculus xvi. 36; Cicero, Tusc. iii. 31; Val. Max. iv. 6.

ARTEMON (fl. c. 230), a prominent Christian teacher at Rome, who held Adoptianist (see ), or humanitarian views, of the same type as his elder contemporaries the Theodotians, though perhaps asserting more definitely than they the superiority of Christ to the prophets in respect of His supernatural birth and sinlessness. He was excommunicated by Zephyrinus, despite his remarkable claim that all that bishop’s predecessors in the see of Rome had held the humanitarian position. (See also .) ARTENA, a village of Italy, in the province of Rome, situated at the N.N.W. extremity of the Volscian Mountains; it is 36 m. S.E. by rail, and 24 m. direct from Rome. Pop. (1901) 5016. On the mountain above it (2073 ft.) are the fine remains of the fortifications of a city built in a very primitive style, in cyclopean blocks of local limestone; within the walls are traces of buildings, and a massive terrace which supported some edifice of importance. The name of this city is quite uncertain; Ecetra is a possible suggestion. The modern village, which was called Monte Fortino until 1870, owes its present name to an unwarrantable identification of the site with the ancient Volscian Artena, destroyed in 404 Another Artena, which belonged to the district of Caere, and lay between it and Veii, was destroyed in the period of the kings, and its site is quite unknown.

See T. Ashby and G. J. Pfeiffer in Supplementary Papers of the American School in Rome, i. 87 seq.

ARTERIES (Gr. , probably from  , to raise, but popularly connected by the ancients with  , air), in anatomy, the elastic tubes which carry the blood away from the heart to the tissues. As, after death, they are always found empty, the older anatomists believed that they contained air, and to this belief they owe the name, which was originally given to the windpipe (trachea). Two great trunks, the aorta and pulmonary artery, leave the heart and divide again and again, until they become minute vessels to which the name of arterioles is given. The larger trunks are fairly constant in position and receive definite names, but as the smaller branches are reached there is an increasing inconstancy in their position, and anatomists are still undecided as to the normal, i.e. most frequent, arrangement of many of the smaller arteries. From a common-sense point of view it is probably of greater importance to realize how variable the distribution of small arteries is than to remember the names of twigs which are of neither surgical nor morphological importance. Arteries adapt themselves more quickly than most other structures to any mechanical obstruction, and many of the differences between the arterial systems of Man and other animals are due to the assumption of the erect position. Many arteries are tortuous, especially when they supply movable parts such as the face or scalp, but when one or two sharp bends are found they are generally due to the artery going out of its way to give off a constant and important branch. Small arteries unite or anastomose with others near them very freely, so that when even a large artery is obliterated a collateral circulation is carried on by the rapid increase in size of the communications between the branches coming off above and below the point of obstruction. Some branches, however, such as those going to the basal ganglia of the brain and to the spleen, are known as “end arteries,” and these do not anastomose with their neighbours at all; thus, if one is blocked, arterial blood is cut off from its area of supply. As a rule, there is little arterial anastomosis across the middle line of the body near the surface, though the scalp, lips and thyroid body are exceptions.

The distribution of the pulmonary artery is considered in connexion with the anatomy of the lungs (see ). That of the aorta will now be briefly described.

The Aorta lies in the cavities of the thorax and abdomen, and arises from the base of the left ventricle of the heart. It ascends forward, upward, and to the right as far as the level of the second right costal cartilage, then runs backward, and to the left to reach the left side of the body of the 4th thoracic vertebra, and then descends almost vertically. It thus forms the arch of the aorta, which arches over the root of the left lung, and which has attached to its concave surface a fibrous cord, known as the obliterated ductus arteriosus, which connects it with the left branch of the pulmonary artery. The aorta continues its course downward in close relation to the bodies of the thoracic vertebrae, then passes through an opening in the (q.v.), enters the abdomen, and descends in front of the bodies of the lumbar vertebrae as low as the 4th, where it usually divides into two terminal branches, the common iliac arteries. Above and behind the angle of bifurcation, however, a long slender artery, called the middle sacral, is prolonged downward in front of the sacrum to the end of the coccyx.

It will be convenient to describe the distribution of the arteries under the following headings:—(1) Branches for the head, neck and upper limbs; (2) branches for the viscera of the thorax and abdomen; (3) branches for the walls of the thorax and abdomen; (4) branches for the pelvis and lower limbs.

The branches for the head, neck and upper limbs arise as three large arteries from the transverse part of the aorta; they are named innominate, left common carotid and left subclavian. The innominate artery is the largest and passes upward and to the right, to the root of the neck, where it divides into the right common carotid and the right subclavian. The carotid arteries supply the two sides of the head and neck; the subclavian arteries the two upper extremities.

The common carotid artery runs up the neck by the side of the windpipe, and on a level with the upper border of the thyroid cartilage divides into the internal and external carotid arteries.

The internal carotid artery ascends through the carotid canal in the temporal bone into the cranial cavity. It gives off an ophthalmic branch to the eyeball and other contents of the orbit, and then divides into the anterior and middle cerebral arteries. The middle cerebral artery extends outward into the Sylvian fissure of the brain, and supplies the island of Reil, the orbital part, and the outer face of the frontal lobe, the parietal lobe, and the temporo-sphenoidal lobe; it also gives a choroid branch to the choroid plexus of the velum interpositum. The anterior cerebral artery supplies the inner face of the hemisphere from the anterior end of the frontal lobe as far back as the internal parieto-occipital fissure. At the base of the brain not only do the two internal carotids anastomose with each other through the anterior communicating artery, which passes between their anterior cerebral branches, but the internal carotid on each side anastomoses with the posterior cerebral branch of the basilar, by a posterior communicating artery. In this manner a vascular circle, the circle of Willis, is formed, which permits of freedom of the arterial circulation by the anastomoses between arteries not only on the same side, but on opposite sides of the mesial plane. The vertebral and internal carotid arteries, which are the arteries of supply for the brain, are distinguished by lying at some depth from the surface in their course to the organ, by having curves or twists in their course, and by the absence of large collateral branches.

The external carotid artery ascends through the upper part of the side of the neck, and behind the lower jaw into the parotid gland, where it divides into the internal maxillary and superficial temporal branches. This artery gives off the following branches:—(a) Superior thyroid to the larynx and thyroid body; (b) Lingual to the tongue and sublingual gland; (c) Facial to the face, palate, tonsil and sub-maxillary gland; (d) Occipital to the sterno-mastoid muscle and back of the scalp; (e) Posterior auricular to the back of the ear and the adjacent part of the scalp; (f) Superficial temporal to the scalp in front of the ear, and by its transverse facial branch to the back part of the face; (g) Internal maxillary, giving muscular branches to the muscles of mastication, meningeal branches to the dura mater, dental branches to the teeth, and other branches to the nose, palate and tympanum; (h) Ascending pharyngeal, which gives branches to the pharynx, palate, tonsils and dura mater.

The subclavian artery is the commencement of the great arterial trunk for the upper limb. It passes across the root of the neck and behind the clavicle, where it enters the armpit, and becomes the axillary artery; by that name it extends as far as the posterior fold of the axilla, where it enters the upper arm, takes the name of brachial, and courses as far as the bend of the elbow; here it bifurcates into the radial and ulnar arteries. From the subclavian part of the trunk the following branches arise:—(a) Vertebral, which enters the foramen at the root of the transverse process of the 6th cervical vertebra, ascends through the corresponding foramina in the vertebrae above, lies in a groove on the arch of the atlas, and enters the skull through the foramen magnum, where it joins its fellow to form the basilar artery; it gives off muscular branches to the deep muscles of the neck, spinal branches to the spinal cord, meningeal branches to the dura mater, and an inferior cerebellar branch to the under surface of the cerebellum. The basilar artery, formed by the junction of the two vertebrals, extends from the lower to the upper border of the pons Varolii; it gives off transverse branches to the pons, auditory branches