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Published on: January 9, 2016
The shoulder extension function of the triceps brachii
Dennis Landin1, Melissa Thompson
1Department of Kinesiology, 112 Long Fieldhouse, Louisiana State University, Baton Rouge, LA 70803, USA. dlandin@lsu.edu
Summary
Shoulder angle significantly impacts triceps brachii (TB) shoulder extension function. Increasing shoulder angle from 0° to 80° enhances TB
Area of Science:
- Biomechanics
- Human Anatomy
- Kinesiology
Background:
- The triceps brachii (TB) is the primary extensor of the elbow and also contributes to shoulder extension.
- As a biarticular muscle, its function is influenced by the interplay of elbow and shoulder joint angles.
Purpose of the Study:
- To investigate how varying elbow and shoulder joint angles affect the shoulder extension function of the triceps brachii.
- To determine the relative importance of shoulder angle versus elbow angle on triceps brachii shoulder extension torque.
Main Methods:
- Eighteen subjects participated in the study.
- Joint moments were measured using a Biodex dynamometer.
- The triceps brachii was selectively stimulated at a standardized voltage.
Main Results:
- Shoulder angle was identified as the most critical factor influencing shoulder extension moment.
- A significant increase in shoulder extension moment was observed as the shoulder angle progressed from 0° to 80°.
- This increase may be attributed to the lengthening of the moment arm at greater shoulder flexion angles.
Conclusions:
- Shoulder joint angle plays a crucial role in modulating the shoulder extension capacity of the triceps brachii.
- Optimal shoulder angles for maximizing triceps brachii contribution to shoulder extension should be considered in rehabilitation and training.
- Understanding these biomechanical relationships can inform therapeutic strategies for shoulder and elbow injuries.
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