Recent knowledge on the cleft hand: it's pathologic pattern and scope.

An experimental system was developed that allows direct measurement of friction at the tendon-pulley interface, and the results were interpreted by use of a theoretical model for friction of a cable around a fixed pulley. Validation experiments were conducted with a nylon cable around a nylon rod. One end of the cable was connected to an actuator via a load cell, and the other end was connected to a 4.9 N load via a similar load cell. The cable was passed around the nylon rod and then pulled toward the actuator. Tests were performed at five different arcs of contact. The friction forces, as measured by the difference between two load transducers, were compared with those determined for a theoretical model and were used for calculation of the friction coefficient. The measurement system then was used to study the friction force between the flexor digitorum profundus tendon and the A2 pulley on nine fresh frozen index digits. The method allows us to measure the direct interaction between the tendon and pulley and could be used to evaluate and compare procedures for tendon-pulley and pulley repair and reconstruction, as well as for the study of tendon-pulley friction in various pathological conditions.

Fingers↗

PubMed1995

Moving one's finger to a visually specified position: target orientation influences the finger's path.

It has previously been shown that, when subjects are instructed to move their finger slowly from one point to another the finger follows a path that deviates systematically from a straight line connecting the two points. The deviation depends on the angle between this fictive line and a line connecting the subject's finger with his body. In the present study, we examined whether the deviation also depends on the target's orientation. In two experiments, subjects were instructed to move a finger slowly towards five targets. We recorded the finger's movements. In one experiment, the targets were aligned. In the other, they were oriented radially around the starting point. Otherwise, conditions were the same. The difference in target orientation influenced the finger's path. Most importantly, when the targets were oriented radially around the starting point, the finger's path was straight. We conclude that pointing is more than moving the finger to a specified position.

Fingers↗