Extension
Extensio
Definition
Extension is defined as a movement which occurs across a joint and leads to an increase in the angle between two body parts or surfaces. For instance, the extension at the knee joint moves apart the posterior surface of the leg from the hamstring region in the thigh, thus increasing the angle between the femur (above) and tibia and fibula (below).
The opposite of extension is flexion which decreases the angle between two body parts or surfaces. Both flexion and extension usually happen along a sagittal plane.
References
Text by Antoine Micheau, MD and reviewed by Muhammad A. Javaid, MD, PhD © 2023 IMAIOS.
Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 6: Lower Limb’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp. 513-516.
Jones, O. (2020). Anatomical terms of movement in ‘TeachMeAnatomy’. Available at URL: https://teachmeanatomy.info/the-basics/anatomical-terminology/terms-of-movement/ [accessed on Feb 11th, 2023]
