Answer: Well, cats normally land on their feet after a fall, provide what is called the head on body righting reflex function correctly.
In the inner ear on both sides of the head are three fluid filled semicircular tubes (called the semi circular canals), each of which is arranged at right angles to the others, i.e. each is one of the three planes of space. In their walls are never ending (vestibular receptors) which detect movement of the fluid and send information about their relative spatial positions to the brain. This means that even when the cat is unable to see it is aware of the position of its head in relation to the ground.
If the cat should happen to fall from height, it first twists its head so that the stop of the head is directed upwards (head righting reflex). Then it twists its neck and the rest of its body so that they ‘line up’ in the normal way with the head the feet will thus be downwards towards the ground. Simultaneous rotation of the body in one direction and rotation of the tail in the other (one moving clockwise and the other counter clockwise) allows this stage to occur rapidly, even through the cat has nothing to grip on to whilst falling.
The entire series of reflex (automatic) movements takes only mille-seconds to happen so that the cat is ‘righted’ very quickly and can land on its feet, thereby avoiding and minimizing any injury. In day light, when the cat can see, visual orientation will inevitably also play a part, but these righting reflexes are not dependant on vision and will occur in total darkness.
Of course, at times these reflexes may not function correctly, or the animal may sustain an injury during its fall, such as hitting a projecting object, with the result that it does not land on its feet. Even if it is correctly righted, the force of the impact with a hard surface, such as concrete, after a lengthy fall can produce serious injuries, especially fractures of the lower jaw and limb bones and damage to initial organs.
