Ok, so it might not be what most people mean by a "sixth sense," but proprioception can at least stake a claim.
It's how the brain senses where each part of the body is, allowing coordinated movement.
It's linked to the fine motor control that enables us to learn and carry out complex physical tasks.
When we're first learning an activity (like learning to drive, playing the piano or learning to play golf), we can be "ham-fisted" - our bodies haven't learned the necessary proprioception. It needs rehearsal and practice to build up.
These are easy to spot (though not necessarily easy to fix!):
There's another obvious time when proprioception is impaired - when we're tired. Then we all get clumsy!
Proprioception relies on constant feedback from the muscles on how contracted they are, so that the brain knows the relative position of every muscle and joint, at any point in time.
All our muscles contain proprioceptors - part of the nervous system that feed back to the brain information about that muscle, such as it's current length and the amount of pressure it's currently under. Special proprioceptors called muscle spindles also feed back to the brain the speed of a stretch that's being undertaken, whilst others called golgi tendon organs (which sit where muscle transition into tendon) feedback consolidated information about the relative tension in different parts of the muscle.
The brain receives this feedback from the proprioceptors and then sends back re-adjustment signals via the nervous system to fine tune the position of the muscle. These readjustment signals include messages about velocity (direction and speed) as well as how much the muscle should move.
This feedback and readjustment mechanism is constant. Sometimes its conscious (we can look our finger and decide how much to wiggle it), sometimes it's unconscious when we've learned a movement well enough.
Regaining proprioception is an important part rehab. If you've broken a bone, or strained a ligament or even suffered a major muscle tear, re-learning fine control of the related muscles is really important.
It's why a physio or remedial massage therapist will give you exercises to increase your range of motion if you've sprained an ankle, for example.
If you don't re-learn the fine control of proprioception early in the rehabilitation stage, it becomes harder to regain as you use other muscles to compensate.
So if you've damaged yourself, expect your therapist to give you some odd exercises that you'll find frustratingly hard - whether it's picking up pencils with your toes, circling your fingers, or whatever it takes to help you re-learn fine control of your muscles.
As ever, if you think I can help, give me a call.