Pain arising from bodily positions must be distinguished from postural discomfort. Posture, physiologically speaking, is the active maintenance of an animal's station in its environment. It is a manifestation of muscular activity sustained largely by proprioceptive reflexes in accordance with inherited nervous patterns, modified by social customs and personal approbations or taboos. It connotes resistance to external forces, such as air currents and gravity. Position, on the other hand, is imposed on a part, and the station is maintained by passive factors. It connotes relaxation and rest. In bed, when one puts one's hands over one's head the arms lie inertly on the pillow. They have position, not posture, because they are not muscularly active but at rest.
Pain may arise from the position imposed on a part if the position is long or frequently maintained. For example, there may be pain in the region of the internal lateral ligament