Types of Movements at Synovial Joints PDF

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Types of Movements at Synovial Joints...

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Types of Movements at Synovial Joints To describe human movement, we need a frame of reference that enables accurate and precise communication. In descriptions of movement at synovial joints, phrases such as “bend the leg” or “raise the arm” are imprecise. Anatomists use descriptive terms that have specific meanings. Spotlight Figure 9–2a (p. 272) provides a simple way to model these different types of movements with a pencil and representative articular surface. Gliding Movement In a gliding movement, two opposing surfaces slide past one another in one plane. Gliding occurs between the flat or nearly flat surfaces of articulating carpal bones, between tarsal bones, and between the clavicles and the sternum. The movement can occur in almost any direction, but the amount of movement is slight, and rotation is generally prevented by the capsule and associated ligaments. Angular Movement Examples of angular movement include flexion, extension, abduction, and adduction (Figure 9–3). Descriptions of these movements are based on reference to an individual in the anatomical position. Linear motion Possible movement 1 shows the pencil can move. If you hold the pencil upright, without securing the point, you can push the pencil across the surface. This kind of motion is called gliding. You could slide the point forward or backward, from side to side, or diagonally. Circumduction

A more complex angular motion is possible. Grasp the pencil eraser and move the pencil in any direction until it is no longer vertical. Now, swing the eraser through a complete circle in a movement called circumduction. Rotation Possible movement 3 shows that the pencil shaft can rotate. If you keep the shaft vertical and the point at one location, you can still spin the pencil around its longitudinal axis in a movement called rotation. No joint can freely rotate because this would tangle blood vessels, nerves, and muscles, as they crossed the joint....