The following is an excerpt from the introduction of this paper: Imagine living a life where even the simplest of tasks such as eating a grape or holding an egg required intense concentration and months of training. Until recently, this was the harsh reality for people with upper limb prostheses. Currently, the most common upper limb prosthetic technology being used is body powered. These devices capture remaining shoulder movements with a harness and transfer this movement through a cable to operate the hand, wrist, or elbow. With this control method, only one joint can be operated at a time. When the amputee has positioned one component, he or she can activate a switch that locks that component in place, and then he or she can operate the next component (Longe 2006; Miguelez et al. 2009; Edeer and Martin 2011). Until recently, this was the only technology available for someone using an upper limb prosthesis.
Moshayev, Y. L. (2012). Targeted Reinnervation. The Science Journal of the Lander College of Arts and Sciences, 6 (1). Retrieved from https://touroscholar.touro.edu/cgi/viewcontent.cgi?article=1121&context=sjlcas