|Cat righting reflex|
This sense is governed by the semicircular canals – six little fluid-bearing canals, three in each ear – that enable cats (and humans) to keep in balance. However, if they played any special part in the wonderful feat of the cat we should expect to find these balancing canals very highly developed in cats; but they are not. Scientists say that man also would be able to alight on their feet when falling if they could think quickly enough. Some men dive head-foremost from a trapeze, turn somersaults in the air and land safely. Others vault over the backs of horses, whirling round in midair as they go, yet drop safely on their feet. All these skills are perfected by much practice so that they become almost instinctive.
Cat righting reflex (Wikipedia)