Foot inversion and eversion movements in stance and swing - some comparative-anatomical and functional morphological aspects (R-3500)

In the lower leg of the common opossum Didelphis marsupialis, the spatium interosseum cruris between tibia and fibula widens in stance during the power stroke, reflecting external rotations of these bones, coupled to extreme inversion of the foot, which lasts until the end of push-off. Although denied in marsupials until recently the strong ligamentum astragalocalcaneum interosseum underlines the importance of our observations. From the very onset of recovery the opossum foot shows eversion. This eversion is coupled to internal rotations of both fibula and tibia in the free leg as is also reflected by the narrowing of the spatium interosseum cruris in the opossum. The precise course of m. interosseus cruris in Didelphis ursina Shaw, suggests its possible active role in this process of repositioning before and during touchdown In man, the foot at the end of stance at push-off shows but a modest inversion which however can be exaggerated to a more extreme inversion of the foot. Then tarsal joints like Chopart's joint and sinus tarsi clearly show their joint spaces on routine radiography. Normally our ligamentum talocalcaneum interosseum restrains this widening. In normal gait, a foot landing after its recovery phase may accidentally do so in a position of inversion, risking a so-called inversion traumatism, the most common ankle sprain. Training proactively e.g. the peroneus muscles, the evertors of the foot, may prevent the incidence of such traumatisms, as suggested by a pilot-study in gymnasts. Extrapolating such methods to the disabled, e.g. in early diagnosed neuropathies, implies possibilities to train these muscles thus protecting Multiple Sclerosis patients from e.g. stumbling and falling.

Keywords:ANATOMY (COMPARATIVE)

Disciplines:Basic sciences, Clinical sciences, Paramedical sciences, Translational sciences