Paper Review Contribution of the extrinsic and intrinsic hand muscles to the moments in finger joints Z.M. Li, V.M. Zatsiorsky, M.L. Latash Clinical Biomechanics 15(2000) 學號： N 學生 : 洪振翔 指導教授 : 朱銘祥 指導教授 : 朱銘祥 林宙晴 林宙晴實驗室：人機系統實驗室2007/05/29

2 Outline Introduction Introduction Goals Goals Methods Methods Modeling Modeling Results Results Discussion Discussion

3 Introduction(1) Extrinsic muscles: originate outside the hand. Extrinsic muscles: originate outside the hand. - responsible for the primary functioning in a variety of tasks - responsible for the primary functioning in a variety of tasks - extensor 、 flexor - extensor 、 flexor Intrinsic muscles: originate and insert within the hand. Intrinsic muscles: originate and insert within the hand. -provide necessary balance and fine tuning of the multi-joints system -provide necessary balance and fine tuning of the multi-joints system

4 Introduction(2) In clinical practice the force of FDP is estimated subjectively. In clinical practice the force of FDP is estimated subjectively. If we want to calculate the moments at the finger joints in static conditions, both the magnitude and direction of the external force must known. If we want to calculate the moments at the finger joints in static conditions, both the magnitude and direction of the external force must known. In this study, a novel measuring system (the suspension system) was developed. In this study, a novel measuring system (the suspension system) was developed.

5 Goals To develop a method of estimating force produced by the flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS) and intrinsic muscles (INT). To develop a method of estimating force produced by the flexor digitorum profundus (FDP), flexor digitorum superficialis (FDS) and intrinsic muscles (INT). To estimate the contribution of these muscles to the finger joint moments. To estimate the contribution of these muscles to the finger joint moments.

6 Methods Apparatus Apparatus -the suspension system -the suspension system Ten right-handed male Ten right-handed male Experimental procedure Experimental procedure 1. three location 1. three location -ExpDP, ExpDIP, ExpPIP -ExpDP, ExpDIP, ExpPIP 2. press down maximally 2. press down maximally -the interphalangeal joints are fully extended -the interphalangeal joints are fully extended 3. EMG of EDC 3. EMG of EDC (extensor digitorum communis) (extensor digitorum communis)

7 Modeling(1) Finger joint moment Finger joint moment Muscles counterbalancing an external finger moment at the joints at different loop positions Muscles counterbalancing an external finger moment at the joints at different loop positions

8 Modeling(2) Analysis of muscle forces and their contribution to joint moment Analysis of muscle forces and their contribution to joint moment

9 Results(1) Contribution of muscle groups to joint moments Contribution of muscle groups to joint moments For ExpDP, For ExpDP, For ExpDIP, For ExpDIP,

10 Results(2) Muscle forces Muscle forces The maximal forces produced by individual muscles depended on the experimental condition. The maximal forces produced by individual muscles depended on the experimental condition.

11 Discussion(1) The “suspension” design in this study is advantageous in that the orientation of force application can be pre- specified. The “suspension” design in this study is advantageous in that the orientation of force application can be pre- specified. In this study the fingers were extended and the force was applied at the middle of the distal phalanx which might be similar to the pulp pinch posture. In this study the fingers were extended and the force was applied at the middle of the distal phalanx which might be similar to the pulp pinch posture. In the model, the contribution of the INT to the extensor mechanism at the PIP and DIP joints was neglected. In the model, the contribution of the INT to the extensor mechanism at the PIP and DIP joints was neglected.

12 Discussion(2) The dorsal and palmar interossei and lumbricals were lumped together and viewed a single muscle that produced a moment solely at the MCP joint. The dorsal and palmar interossei and lumbricals were lumped together and viewed a single muscle that produced a moment solely at the MCP joint. The assumption is justified because in the experiments the fingers were extended. The assumption is justified because in the experiments the fingers were extended. As a result, the effects of extensor mechanism are relatively small when the point of force application is at distal position. As a result, the effects of extensor mechanism are relatively small when the point of force application is at distal position.

13 Thanks for your attention