DETECTION OF MOVEMENTS IMPOSED ON HUMAN HIP, KNEE, ANKLE AND TOE JOINTS

1. The angular displacements necessary for 70% correct detection were determined in normal subjects at the hip, knee and ankle joints, and t he interphalangeal joint of the big toe. Angular velocities between 0. 1 and 50 deg s(-1) were tested. The hip and knee joints were tested in slight flexion and the ankle and toe joints were tested in the mid-ra nge of the normal excursion. The joints were carefully supported for t esting and the muscles acting at the joints were relaxed. 2. When dete ction thresholds and velocities were assessed in terms of angular disp lacements and angular velocities, proprioceptive performances at the h ip, knee and ankle joints were superior to that at the toe joint. 3. W hen detection levels and displacement velocities were expressed in ter ms of linear displacements and velocities at the tip of the extended t oe for all four joints, instead of in angular terms, the ankle gave th e best performance and the hip and knee the worst. 4. The detection le vel and velocity data were expressed also in terms of proportional cha nges in the fascicle lengths of muscles operating these joints. Analys is in these terms showed that performance was similar at the hip, knee and ankle joints, but that performance for the toe was much poorer th an for the other joints. 5. These results for the hip, knee and ankle are similar to those previously measured for the elbow and distal inte rphlangeal joint of the finger, and are consistent with the theory tha t muscle fascicle length is the variable of significance to the centra l nervous system. However, the proprioceptive performance at the big t oe is notably poorer than all other joints studied and analysed in ter ms of this variable.