The classic. Mechanism of shoulder movements and a plea for the recognition of "zero position" of glenohumeral joint.
1. Locking of greater tuberosity against acromion never takes place in any position of abduction. 2. Rolling down movement of humeral head in glenoid inevitably takes place while lifting the arm either in flexed or in abducted position. 3. Forward shift of clavicle with the scapula at the sterno-clavicular joint is an important event during elevation of shoulder joint complex overhead. 4. From theoretical static considerations an attempt has been made to show that properly harnessed biceps and triceps (long heads) may take the place of depressors of the head of the humerus. 5. Recognition of 'zero-position' of the gleno-humeral joint is advocated. 6. Perfect reduction of unimpacted fracture of humeral neck has been shown to be possible if it is carried out in this 'zero-position'.
D001696:Biomechanical Phenomena; D002968:Clavicle / Q000502:physiology; D006801:Humans; D006811:Humerus / Q000502:physiology*; D008433:Mathematics; D009068:Movement; D009132:Muscles / Q000502:physiology; D012540:Scapula / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*