Finger movements have primarily been classified by the final position of the hand and finger during deliberate hand activities, rather than as a description of the movement process. In addition, as of yet there have been no reports based upon objective data from the analysis of the motion of three finger joints during movement, and no reports exist that describe the relationship of the three joints' motion during these movements. This paper describes the relationship of the three finger joints during simple finger movements and hand tasks using measurements and analysis from a two-dimensional motion analyzer. Two prehensile movements were examined in 15 healthy volunteers: pure finger extension from finger flex position in different wrist positions (dorsi-flexion position, neutral position and palmar-flexion position of the wrist joint) and the grasping of discs of different diameter (10, 11, 12 and 13 cm). In the sequence of pure finger extension, where the grasping task was not requested, results showed that the movement was started from the proximal joint and extended to the distal joint of the finger, and full finger extension accomplished from distal to proximal, one after another, in any wrist position in most subjects. With the grasping of a disc, however, joint movement was initiated from distal to proximal and the final motion for grasping was carried to completion from the proximal to distal joints of the finger in most subjects. In addition, it was recognized that the proportion of the angular change in each of the three joints was different, as were the time duration of the joint motion and the pattern of the angular change. From these results, it is suggested that deliberate activities of the finger and sophisticated joint movements provided delicate adjustments to fit the fingers to the size of the object, as compared to the simple finger extension movement.

The shoulder joint allows three-dimensional movement. In order to analyze the function of the muscles which act on the shoulder joint, three-dimensional movements, including rotation, must be considered. Among muscles participating in the shoulder joint movement, the supraspinatus muscle is known to have abduction and stabilization effects on the shoulder joint. However, the rotational function of the supraspinatus muscle has not been identified, because few studies have been reported on it. This study investigates the rotating function of the supraspinatus muscle using electrical stimulation, magnetic resonance imaging (MRI) and anatomical examination. Electrical stimulation was applied selectively to the supraspinatus muscle of healthy subjects using percutaneous wire electrodes. The electrical stimulation was given at different positions of the shoulder joint. It was found that the electrically induced rotational movements changed their direction depending on the position of the shoulder joint. When the humerus was relatively in internal rotation, internal rotation resulted. When it was in external rotation, external rotation occurred. Regarding the abduction angle of the shoulder joint, external rotation was induced with an increase in the abduction angle, whereas internal rotation occurred when the abduction angle was decreased. By the dissection of cadavers and MRI examination, it was indicated that the relation between the running direction of the supraspinatus muscle and the center of rotation of the humeral head was dependent on the position of the shoulder joint. Those findings supported the results of electrical stimulation of the supraspinatus muscle at various shoulder positions. These results indicate that the bi-directional rotating function of the supraspinatus muscle is characterized by an anatomical relationship between the running direction of the supraspinatus muscle and the center of rotation of the humeral head.

This paper describes effects of therapeutic electrical stimulation(TES) on progressively deteriorating muscles in 28 patients with amyotrophic lateral sclerosis (ALS). A multichannel percutaneous FES system which we developed was used in order to apply cyclic stimulation to the affected muscles automatically. Within one or two weeks TES therapy, many patients showed an improvement of voluntary motion due to afferent effects of TES. Long-term TES therapy more than 6 months resulted in the increment or maintenance of muscle strength in some of these patients. CT findings of the TES treated muscles in these patients showed an increase in muscle density and a decrease in moth-eaten image. Thus it is likely that TES is effective for the treatment of ALS.

This paper describes the effects of therapeutic electrical stimulation (TES) on the wasting muscles in a patient with amyotrophic lateral sclerosis. The patient is a 47-year-old male, and he has a history of progressive muscle weakness and atrophy, affected more in the right side. Percutaneously indwelling intramuscular electrodes were implanted to the affected muscles in the right upper and lower extremities but no electrode in the corresponding left region. Within a month of TES therapy, a rapid improvement of extremity motion appeared in the TES treated side. Long-term application of TES more than 3 months increased the strength of the muscle which had been evidently weaker than the non-treated side. CT findings of both the upper and lower extremities with TES therapy showed an increase in the density and a reduction in the moth-eaten image. An increase in the thickness of the muscles was also observed in the TES treated side while deterioration was observed in the muscles on the non-treated side.