The process of straitening or the state of being strait. Extension of the hip and knee joints is necessary to stand up from the sitting position.
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1. The act of bringing the distal portion of a joint in continuity (though only parallel) with the long axis of the proximal portion. 2. A pulling or dragging force exerted on a limb in a distal direction. 3. Obsolete term for traction. [L. extensio, a stretching out]
- Buck e. SYN: Buck traction.
- primer e. a technique for determining the 5′-untranslated region of a specific mRNA molecule. Uses an oligonucleotide complementary to the known RNA sequence as a primer for cDNA synthesis via reverse transcriptase.
- ridge e. an intraoral surgical operation for deepening the labial, buccal, and/or lingual sulci; it is performed to increase the intraoral height of the alveolar ridge in order to assist denture retention.
- skeletal e. SYN: skeletal traction.

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ex·ten·sion ik-'sten-chən n
1) the stretching of a fractured or dislocated limb so as to restore it to its natural position
2) an unbending movement around a joint in a limb (as the knee or elbow) that increases the angle between the bones of the limb at the joint compare FLEXION (1)

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1. the act of extending or stretching, especially the muscular movement by which a limb is straightened.
2. the application of traction to a fractured or dislocated limb in order to restore it to its normal position.

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ex·ten·sion (ek-stenґshən) [L. extensio] 1. the movement that straightens or increases the angle between the bones or parts of the body. 2. the bringing of the members of a limb into or toward a straight relation. 3. enlargement or prolongation.

Medical dictionary. 2011.