Proprioception
The ability to sense stimuli arising within the body.
Even if you are blindfolded, you know through proprioception if your arm is above your head or hanging by your side.
The word 'proprioception' was coined in 1906 by the English neurophysiologist Charles Sherrington who received the Nobel Prize for Physiology or Medicine in 1932 for research on the function of the neuron and study of reflex action.