Arm (redirected from Arm (disambiguation))

arm, upper limb in humans. Three long bones form the framework of the arm: the humerus of the upper arm, and the radius (outer bone) and ulna (inner bone) of the forearm. The radius and ulna run parallel but meet at their ends in such a manner that the radius can rotate around the ulna. This arrangement permits turning the forearm to bring the hand palm up (supination) or palm down (pronation). The radius and ulna hinge with the bones of the hand at the wrist, and with the humerus at the elbow. The biceps brachii, a muscle of the upper arm, bends the arm at the elbow; the triceps brachii straightens the arm. Movement of the arm across the chest and above the head is accomplished by the pectoral muscles of the chest and deltoid muscles of the shoulder, respectively. In an adult the arm is normally five sixths as long as the leg.

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arm

Upper limb of a biped, particularly a primate. Primate arms have one long bone, the humerus, in the upper arm above the elbow, and two thinner bones, the radius and ulna, in the forearm. The triceps muscle straightens the forearm at the elbow joint; the brachialis and biceps muscles bend it. Forearm and small muscles in the hand move the hand and fingers. The term may also denote the limb or the locomotive or prehensile organ of an invertebrate (e.g., the ray of a starfish or the tentacle of an octopus).

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arm [ärm]

(anatomy)

The upper or superior limb in humans which comprises the upper arm with one bone and the forearm with two bones.

(control systems)

A robot component consiting of an interconnected set of links and powered joints that move and support the wrist socket and end effector.

(electricity)

branch

(engineering acoustics)

tone arm

(geology)

A ridge or a spur that extends from a mountain.

(mathematics)

A side of an angle.

(naval architecture)

The part of an anchor extending from the crown to one of the flukes.

(oceanography)

A long, narrow inlet of water extending from another body of water.

(ordnance)

A combat branch of a military force; specifically, a branch of the U.S. Army, such as the Infantry Armored Cavalry, the primary function of which is combat.

(Often plural)Weapons for use in war.

To supply with arms.

To ready ammunition for detonation, as by removal of safety devices or alignment of the explosive elements in the explosive train of the fuse.

(physics)

The perpendicular distance from the line along which a force is applied to a reference point.

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1.	(processor)	ARM - Advanced RISC Machine. Originally Acorn RISC Machine.
2.	(company)	ARM - Advanced RISC Machines Ltd.
3.	(publication)	ARM - ["The Annotated C++ Reference Manual", Margaret A. Ellis and Bjarne Stroustrup, Addison-Wesley, 1990].
4.	(hardware)	ARM - Active Reconfiguring Message.

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Arm 

the upper extremity in man consisting of the shoulder, forearm, and hand (carpus, metacarpus, and phalanges of the fingers). The arm is a more developed grasping extremity in man than in man’s ancient ancestors, the Anthropomorphidae.

The transformation from Anthropomorphidae to man was largely promoted by freeing the anterior extremities, or arms, from locomotion and body-support functions and converting them into organs capable of performing work operations. As the arm became adapted to work, its structure substantially changed, becoming sharply distinct from the structure of the anterior extremity of Anthropomorphidae.

The most significant structural changes occurred in the hand. In Anthropomorphidae the hand has an underdeveloped thumb and the remaining fingers are greatly elongated; in contrast, the human hand is characterized by a powerfully developed thumb that is essential in performing all work operations. The remaining fingers of the human hand are significantly shorter than those of Anthropoidea but are nevertheless capable of the most delicate and differentiated movements.

In man’s development, the development of the arm as a work organ occurred simultaneously with the progressive development of the brain.

The body processes in brachiopods, the tentacles in cephalopods, and the mobile or nonmobile rays of echinoderms are sometimes called arms.