ABSTRACT
The life of every animal requires the detection and regulation of mechanical forces. These forces can be caused by factors in the environment or may be generated by an animal’s own movements and muscular contractions. In these processes, multicellular animals are aided invaluably by information provided by sensory neurons known as mechanoreceptors, which respond specifically to mechanical forces. The responses of mechanoreceptors are often limited to a single modality, such as touch, pressure, or detection of muscle tension, based upon their location in the body and specializations of their receptive endings. Sherrington 1 , 2 proposed that different types of mechanoreceptors could be grouped according to the source of the forces to which they respond: he termed “exteroceptors” those sense organs that respond mainly to forces generated by the environment and “proprioceptors” those afferents that respond predominantly to forces produced by the animal itself. In mammals, touch receptors in the dermis of the skin are examples of exteroceptors while receptors in muscles joints and tendons are exemplary proprioceptors.
