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Upper extremity injuries
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Ronald F. Zernicke, William C. Whiting, Sarah L. Manske
Rotator cuff: The rotator cuff undergoes considerable tension, particularly in throwing and swimming and is a frequent site of injury. The rotator cuff comprises the supraspinatus, infraspinatus, subscapularis, and teres minor muscles. The etiology for many injuries in the rotator cuff region is multifactorial, and frequently there is more than one problem that leads to diagnosis. There is a strong relation among glenohumeral impingement, joint instability, and rotator cuff pathology. Here, we present some of the signs and diagnoses related to the rotator cuff.
The Anatomy of Human Motion
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Infraspinatus and teres minor rotate the humerus laterally. The subscapularis is the strongest and the largest muscle of the rotator cuff. It prevents the head of the humerus to be pulled upwards by the deltoid, biceps, and long head of triceps. This muscle medially rotates the humerus.
Shoulder problems
Published in Richard Graveling, Ergonomics and Musculoskeletal Disorders (MSDs) in the Workplace, 2018
The teres minor muscle stems from the outer border of the scapula and runs across the back of the shoulder joint to attachments on both the humerus (greater tubercle) and the joint capsule. It functions primarily to externally rotate the arm and secondarily to depress the humeral head.
Softball pitching mechanics and shoulder injuries: a narrative review
Published in Sports Biomechanics, 2023
Paul D. Minetos, Jeffrey D. Trojan, Symone M. Brown, Mary K. Mulcahey
The kinematic findings of Maffet and Rojas highlight important concepts regarding windmill pitching mechanics and potential injury sites within the shoulder. During the windup phase, from the 6 o’clock to 3 o’clock positions, the supraspinatus muscle acts to maintain the humeral head centralised within the glenoid cavity (Maffet et al., 1997). Additionally, supraspinatus acts as a fulcrum to prevent superior translation of the humerus during humeral elevation initiated by the deltoid. Infraspinatus acts as an external rotator of the humerus at a lower elevation, and teres minor acts similarly as the humerus elevates between the 3 o’clock and 12 o’clock positions. Maximal activity of infraspinatus and the posterior deltoid occurs from 3 to 12 o’clock, where the humerus is elevated and externally rotated. Softball players with rotator cuff pathologies likely experience injury during this phase. Care should be taken to differentiate which of the rotator muscles are injured and to use muscle-specific exercise and rehabilitation modalities (Maffet et al., 1997).
Biomechanical upper-extremity performance tests and isokinetic shoulder strength in collision and contact athletes
Published in Journal of Sports Sciences, 2021
Edel Fanning, Katherine Daniels, Ann Cools, Josh J. Miles, Éanna Falvey
The upper-extremity performance tests did not appear to be related to shoulder rotational strength. This observation may be for a number of reasons. Rotational strength may not correlate directly with the ability to produce force in the push horizontal plane. However, studies have examined electromyography activity and recruitment of the rotator cuff muscles during exercises in the push horizontal plane such as the bench press (Wattanaprakornkul et al., 2011). They have demonstrated significantly higher posterior rotator cuff (supraspinatus, infraspinatus and teres minor) activity during bench press hypothesizing that the rotator cuff provides shoulder joint support by preventing the prime movers that flex the humerus from translating the humeral head anterior on the glenoid fossa in the bench press (Wattanaprakornkul et al. 2011). Perhaps another reason the performance tests show no correlation with rotational strength is that other variables such as trunk and hip control in the kinetic chain may influence the outcome of the tests described. The Upper Quarter Y-Balance Test (UQYBT), a closed kinetic chain reaching test, did not directly correlate with shoulder isometric strength, however was significantly associated (albeit it weak) with dynamic tests involving core stability (Westrick et al., 2012). These findings would support the theory that other variables within the kinetic chain play a part in closed kinetic chain upper quadrant tests.
Sex Differences in Rotator Cuff Muscles’ Response to Various Work-Related Factors
Published in IISE Transactions on Occupational Ergonomics and Human Factors, 2021
Hossein Motabar, Ashish D. Nimbarte
Three rotator cuff muscles were studied: the supraspinatus, infraspinatus and teres minor muscles. Although the subscapularis is a rotator cuff muscle, the deep positioning of this muscle impairs proper surface EMG data collection; thus, the subscapularis was excluded. Muscle-specific MVCs were performed and subsequently four submaximal exertions were completed using force levels equivalent to 15, 30, 45, and 60% MVC. These exertion levels were based on the results of our prior study Motabar et al., 2019, which indicated that exertions at levels below 15% MVC do not generate distinguishable differences between muscles, while exertions at levels above 60% MVC were strenuous for most of the participants. Muscle activity, endurance time, and subjective ratings of perceived exertion (RPE) were recorded during submaximal exertions.