The functional state of the muscles is one of the important indicators of the influence of life factors on the growing child's body. Sedentary sedentary lifestyle of modern children negatively affects the development of body systems, including musculoskeletal. The aim of the study was to assess the functional state of the muscles and ligaments of the shoulder joints in younger schoolchildren of different sexes, taking into account lateral asymmetry and dynamics features during the school year. Methodology and organization of the study. Functional muscle testing of 265 students of grades 2-3 was carried out using tests to assess the volume of movement in the shoulder joints, consisting in locking the fingers of the hands with the establishment of the right and left hands alternately behind the back. The results of the study. The high frequency of the prevalence of the stiffened muscles of the shoulder girdle in children of primary school age was revealed. Lateral asymmetry of the functional state of the shoulder girdle muscles was established. The fixation of the shoulder girdle muscles was noted more often in boys than in girls. It is shown that in the dynamics of the academic year at the trend level, there was a deterioration in the functional state of the muscles due to the influence of negative factors of the educational environment. Conclusions. The data obtained make it necessary to integrate physical exercises for stretching the muscles and ligaments of the shoulder girdle into all forms of organized physical activity of younger schoolchildren, including physical education classes, changes between lessons and physical education minutes in the classroom