The contribution of articular receptors to proprioception with the fingers in humans

1. Whether joint receptors contribute demonstrably to proprioception has remained uncertain. Therefore, we tested whether an articular contribution to movement sense could be revealed if the total sensory input available to signal joint movement were reduced by eliminating movement signals from muscles. With a reduced sensory input, whatever contribution articular receptors made to proprioception ought to assume a greater-than-normal importance, and any effect of eliminating articular inputs should become more apparent. The distal interphalangeal joint of the middle finger was used, because the muscles could be decoupled from this joint by positioning the fingers to slacken the tendons. 2. To further enhance the possibility for observing an effect of eliminating articular contributions, we planned to test movement sense at positions of the joint in which the articular receptors would be most active. However, the response properties of receptors in primate finger joints were unknown, so we examined activity of receptors in finger joints of monkeys prior to testing humans. 3. Activity of receptors in interphalangeal joints of monkeys was measured over a wide range of positions before and during local anesthesia of the joint. Little response was seen over intermediate positions, but activity increased as the joint approached full flexion or full extension in much the same manner as responses previously observed with receptors in the knee, elbow, wrist, and hip joints. Local anesthetic injected into the joint space abolished the nerve activity. 4. Proprioception was tested in humans before and during local anesthesia of the joint using a movement-detection paradigm.(ABSTRACT TRUNCATED AT 250 WORDS)