Kinematics of the Shoulder Girdle During Pointing: Coordination Between Joints and their Contribution to the Peri-Personal Workspace.
This study explored the coordination between the components of the shoulder girdle (clavicle, scapula and humerus), and how they contribute to hand movement in the peri-personal space. Shoulder girdle motion was recorded in 10 healthy subjects during pointing movements to 9 targets in the peri-personal space, using electromagnetic sensors fixed to the trunk, scapula and upper arm. Most of the 9 degrees of freedom (DoF) of the shoulder girdle were finely scaled to target position. Principle component analysis revealed that the 6 DoF of scapula-thoracic motion were coordinated in three elementary patterns (protraction, shrug and lateral rotation). The ratio of gleno-humeral to scapulo-thoracic global motion was close to 2:1. A direct kinematic procedure showed that if no scapular motion occurred, the workspace would be reduced by 15.8 cm laterally, 13.7 cm vertically and 4.8 cm anteriorly. Scapulo-thoracic motion should be taken into account when investigating the physiology of upper-limb movements.
1 Sorbonne University.
Agnès
A
Roby-Brami
2 Raymond Poincaré Hospital.
Johanna V G
JV
Robertson
3 Cochin Hospital.
Alexandra
A
Roren
3 Cochin Hospital.
Marie-Martine
MM
Lefèvre-Colau
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009038:Motion; D016059:Range of Motion, Articular / Q000502:physiology*; D012785:Shoulder Joint / Q000503:physiopathology*
clavicle; direct kinematics; motion analysis; redundancy; scapula; workspace