© Cambridge University Press 2013. There are two major cognitive control systems that help the human program movements. One system helps determine when to move and the other how to move. Akinesia, or hypokinesia, is a disorder in the “when” or “action-intentional system.” Some of the other disorders of the action-intentional system include motor impersistence, defective response inhibition, and motor perseveration. Although these disorders are caused by brain damage and are terribly disabling, this chapter will focus on the disorders of the “how” system. The term apraxia was originally used by Steinthal in 1871  to describe a misuse of tools and objects, a disorder of the “how” system. Although the term apraxia, derived from Greek, literally means “without action,” the word akinesia is used currently to describe the failure to initiate an action in the absence of weakness. The term apraxia has been used for a variety of how-movement disorders including disorders of gait, speech and eye control, but this chapter will focus on apraxia of the upper limbs. Apraxia of the forelimbs can be task specific or general. Task-specific apraxias include dressing apraxia and constructional apraxia; these specific forms of apraxia will not be discussed in this chapter, which instead will focus on the general forms of apraxia.