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Humerus

Last updated: July 15, 2018

What Does Humerus Mean?

The humerus is the long bone of the arm that extends from the shoulder to the elbow. The bone connects to the bones of the lower arm at the elbow and the scapula at the shoulder. The humerus serves as the support and anchoring system for the major muscles of the upper arm. Movements of both the upper and lower arm and flexion of the elbow involve the exertion of muscles connected to the humerus. The humerus is part of a musculoskeletal system that is particularly sensitive to repetitive motion and stress-related injury although the humerus itself is most likely to be injured through impact or stressors than purely repetitive motion.

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WorkplaceTesting Explains Humerus

The humerus bone is the only bone of the upper arm. It is a long bone, consisting of a narrow body with two terminal points. This single bone is the primary structural support for the muscles of the upper arm and thus is essential for arm movement. The head of the humerus is at its proximal end and meets the shoulder where it forms the most flexible joint in the human body. The ball-and-socket joint formed by the humerus and scapula is called the glenohumeral joint. This joint is surrounded by a ring of cartilage and the muscles of the rotator cuff.

While this skeletal construction allows for great flexibility and range of movement, it also makes the shoulder joint susceptible to weakness and dislocation. The shaft of the humerus is smooth with a shallow groove called the bicipital or intertubercular groove along its upper length that channels the bicep muscles toward the scapula. A bump near the midpoint is called the deltoid tuberosity. This bony protrusion serves as a connector for the large deltoid muscle. At the distal end of the humerus are two points that connect to the radius and ulna of the lower arm. The hinge joint between the ulna and humerus controls the flexion of the elbow, while the joint between the humerus and radius permits supination and pronation of the arm.

Wear or injury to these connections at the elbow can significantly impair movement. In the workplace setting, ergonomic design must ensure that the upper arm is not subject to awkward positioning or repetitive strain to avoid painful injuries and loss of productivity.

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