title: Electromyography of shoulder muscles in relation to force direction.
abstract: In a static force task the electromyographic level of 14 shoulder muscles including 3 rotator cuff muscles was related to force direction. Surface and wire electrodes were used. The force direction of maximal electromyography (principal action) was identified for every muscle. The principal action expresses the function of a muscle in a special situation. The deltoid was active in a force direction that could be understood from its anatomy. The trapezius and serratus were mainly involved in stabilizing the scapula in upward and outward force directions. Large multiarticular muscles such as the pectoralis and the latissimus were active in downward and forward forces. The rotator cuff seems to have a specific role in stabilizing the glenohumeral joint. These data can be compared with data of patients with shoulder disorders and with kinematic data of a shoulder model.
authors.affiliation: State University of Leiden, Research Group of Kinesiology, Department of Orthopedics, Delft University of Technology, Leiden, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Arwert
authors.forename: J
authors.initials: J
authors.lastname: de Groot
authors.forename: W W
authors.initials: WW
authors.lastname: Van Woensel
authors.forename: P M
authors.initials: PM
authors.lastname: Rozing
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D017006:Rotator Cuff / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*