This chapter discusses the morphological and physiological characteristics of joint receptors and the function of these receptors in motor control and proprioception. All joints are innervated by primary and accessory nerves. For instance, the knee joint is innervated by three nerves that contain afferent fibers primarily destined for articular tissues: the posterior articular nerve, the medial articular nerve, and the lateral articular nerve. All articular nerves contain myelinated and unmyelinated axons. In early investigations with light microscopy, an even proportion of myelinated and unmyelinated afferents was observed in the posterior and medial articular nerves of the knee joint. Morphologically, capsules are by far the most extensively investigated joint structure. They contain all receptor types, except the Golgi tendon organlike endings.