Overall shoulder motion consists of substantial angular rotations at each of the four shoulder joints, enabling the multiple-joint interaction required to elevate the arm overhead.

© Revista Brasileira de FisioterapiaScapular and rotator cuff muscle activity during arm elevation: A review of normal function and alterations with shoulder impingement Atividade dos músculos escapulares e do manguito rotator durante a elevação do braço: Uma revisão da função normal e das alterações na síndrome do impacto Phadke V 1 , Camargo PR 2 , Ludewig PM 3 AbstractObjective: The purpose of this manuscript is to review current knowledge of how muscle activation and force production contribute to shoulder kinematics in healthy subjects and persons with shoulder impingement. Results: The middle and lower serratus anterior muscles produce scapular upward rotation, posterior tilting, and external rotation. Upper trapezius produces clavicular elevation and retraction. The middle trapezius is primarily a medial stabilizer of the scapula. The lower trapezius assists in medial stabilization and upward rotation of the scapula. The pectoralis minor is aligned to resist normal rotations of the scapula during arm elevation.The rotator cuff is critical to stabilization and prevention of excess superior translation of the humeral head, as well as production of glenohumeral external rotation during arm elevation. Alterations in activation amplitude or timing have been identified across various investigations of subjects with shoulder impingement as compared to healthy controls. These include decreased activation of the middle or lower serratus anterior and rotator cuff, delayed activation of middle and lower trapezius, and increased activation of the upper trapezius and middle deltoid in impingement subjects. In addition, subjects with a short resting length of the pectoralis minor exhibit altered scapular kinematic patterns similar to those found in persons with shoulder impingement. Conclusion: These normal muscle functional capabilities and alterations in patient populations should be considered when planning exercise approaches for the rehabilitation of these patients.Key-words: electromyography; muscle activation; scapula; shoulder pain. ResumoObjetivo: O objetivo deste manuscrito é revisar o conhecimento atual sobre como a ativação muscular e a produção de força contribuem para a cinemática do ombro em indivíduos saudáveis e em pessoas com síndrome do impacto. Resultados: As porções média e inferior do músculo serrátil anterior produzem rotação para cima, inclinação posterior e rotação externa na escápula. O trapézio superior produz elevação e retração da clavícula. O trapézio médio é principalmente um estabilizador medial da escápula.O trapézio inferior auxilia na estabilização medial e rotação para cima da escápula. O músculo peitoral menor está alinhado para resistir às rotações normais da escápula durante a elevação do braço. O manguito rotador é crucial para a estabilização e prevenção do excesso de translação superior da cabeça do úmero, assim como para a produção de rotação externa na glenoumeral durante a elevação do braço. Foram identificadas alterações na amplitude ou no tempo de ativação em diversas inve...

There were group differences. Eversion of the calcaneus and adduction of the first ray were increased, and the first-ray axis was inclined 24 degrees over middle stance in women with deformity compared with 6 degrees in control participants. Results may identify risk factors of hallux valgus and inform nonoperative treatment (orthoses, exercise) strategies.

Conclusions about normal and pathologic shoulder motion are frequently made from studies using skin surface markers, yet accuracy of such sensors representing humeral motion is not well known. Nineteen subjects were investigated with flock of birds electromagnetic sensors attached to transcortical pins placed into the scapula and humerus, and a thermoplastic cuff secured on the arm. Subjects completed two repetitions of raising and lowering the arm in the sagittal, scapular and coronal planes, as well as shoulder internal and external rotation with the elbow at the side and abducted to ninety degrees. Humeral motion was recorded simultaneously from surface and bone fixed sensors. The average magnitude of error was calculated for the surface and bone fixed measurements throughout the range of motion. ANOVA tested for differences across angles of elevation, raising and lowering, and differences in body mass index. For all five motions tested, the plane of elevation rotation average absolute error ranged from 0-2°, while the humeral elevation rotation average error ranged from 0-4°. The axial rotation average absolute error was much greater, ranging from 5° during elevation motions to approaching 30° at maximum excursion of internal/external rotation motions. Average absolute error was greater in subjects with body mass index greater than 25. Surface sensors are an accurate way of measuring humeral elevation rotations and plane of elevation rotations. Conversely, there is a large amount of average error for axial rotations when using a humeral cuff to measure glenohumeral internal/external rotation as the primary motion.

Glenohumeral motion presents challenges for its accurate description across all available ranges of motion using conventional Euler/Cardan angle sequences without singularity. A comparison of the description of glenohumeral motion was made using the ISB recommended YX'Y" sequence to the XZ'Y" sequence. A direct in-vivo method was used for the analysis of dynamic concentric glenohumeral joint motion in the scapular plane. An electromagnetic tracking system collected data from ten healthy individuals while raising their arm. There were differences in the description of angular position data between the two different sequences. The YX'Y" sequence described the humerus to be in a more anteriorly rotated and externally rotated position compared to XZ'Y" sequence, especially, at lower elevation angles. The description of motion between increments using XZ'Y" sequence displacement decomposition was comparable to helical angles in magnitude and direction for the study of arm elevation in the scapular plane. The description of the direction or path of motion of the plane of elevation using YX'Y" angle decomposition would be contrary to that obtained using helical angles. We recommend that this alternate sequence (XZ'Y") should be considered for describing glenohumeral motion.

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These findings suggest that orthotic arch support could reorient the metatarsal joint axis out-of-vertical and in effect, limit the first metatarsal from displacing into an adducted bunion deformity. These findings could help to explain the pathogenesis of bunions.

BackgroundThere currently are no recommended standards for reporting kinematics of the first-metatarsophalangeal joint. This study compared 2 different rotation sequences of Cardan angles, with implications for understanding the measurement of hallux valgus deformity.MethodsThirty-one women (19 hallux valgus; 12 controls) participated. All were scanned in an open-upright magnetic resonance scanner, their foot posed to simulate the gait conditions of midstance, heel-off, and terminal stance. Using computer processes, selected tarsals were reconstructed into virtual bone models and embedded with principal-axes coordinate systems, from which the rotation matrix between the hallux and first metatarsal was decomposed into Cardan angles. Joint angles were then compared using a within factors (rotation sequence and gait condition) repeated-measures analysis of variance (ANOVA).ResultsOnly the transverse plane-first sequence consistently output incremental increases of dorsiflexion and abduction across gait events in both groups. There was an interaction (F ≥ 25.1; p < 0.001). Follow-up comparisons revealed angles were different (p < 0.05) at terminal stance.ConclusionsDifferent rotation sequences yield different results. Extracting the first rotation in the transverse plane allows for the resting alignment of the hallux to deviate from the sagittal plane. Therefore, representing first-metatarsophalangeal joint kinematics with the transverse plane-first rotation sequence may be preferred, especially in cases of hallux valgus deformity.