ARLON (am Orolanum), a t. of Belgium, the capital of the province of Luxemburg, 24 m. w.n.w. from Luxemburg. It is a neat and prosperous town, and has a consider able trade in corn, woolen stuffs, leather, iron, etc. It has frequently suffered the ravages of war. The French pillaged it in 1793, after a victory won in its neighborhood over the Austrians. Pop. '70, about 5800.
AR11,the upper extremity of the human body, consists of two portions— the A.. strictly so called, and the forearm; the former having one bone, the humerus, which moves freely by a globular head upon the a .i ." scapula, forming the shoulder-joint; and the latter having two bones, the radius and ulna, which move on the lower end C! '' of the humerus, forming the elbow-joint, and below, with the b"x carpus, forming the wrist. it :, ." 4: ,Y' The humerus is attached by a loose capsular ligament to / the scapula, allowing great freedom of motion; and were it 1 - -4not for the muscles, would be frequently dislocated, but it is c.•-• ' A'' t supported by muscles on all sides except underneath or '., opposite the armpit, into which the head of the bone is often , - --r — l' Ydriven. The roundness of the shoulder is due to the head of • ti' ii the humerus, so that any displacement is accompanied by a !''' '4 ": '.
flattening, which at once suggests the nature of the accident. , , On the shoulder there is a large triangular muscle, the ' ^ i deltoid, which lifts the A. from the side. At the back is the triceps, which extends the forearm; in front are two muscles .° t — --.. r. a/W which flex or bend it—the biceps, and the brachialis anticus; and on each side below are muscles passing to the forearm ,p, and hand; while on each side, above the great muscle of the back (latissinius dorsi) and that of the chest (the pectoralis ti it ' .---tm major) are inserted on each side of a groove, wherein lies one of the tendons of the biceps (q.v.). The motions of the ulna o- .
are flexion or bending effected by the biceps, and extension k or straightening by the brachialis milieus and the triceps, its /. . 1 ...1 projections D and A being received in these movements into corresponding depressions on the humerus. The move ments of the hand are principally due to the radius, the r head of which rolls at C and upon the ulna at F and L, 1 ' thereby turning the palm downwards (pronation), or restor ing the palm upwards (supination), these movements being