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Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Musculus semitendinosus is situated on the posteromedial part of the thigh and extends between the ischial tuberosity and the tibia bone. Insertion: The origin is on the ischial tuberosity. The bulk of this muscle is gently divided by a tendinous intersection. Distal insertion is on the anterior proximal tibial shaft. Action: It is an extensor of the femur and a flexor of the knee. It has more force than biceps femoris. Innervations are given by the sciatic nerve having two branches (L5 and S1, 2).
Effects of backrest and seat-pan inclination of tractor seat on biomechanical characteristics of lumbar, abdomen, leg and spine
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Qichao Wang, Yihuan Huo, Zheng Xu, Wenjie Zhang, Yujun Shang, Hongmei Xu
In this study, the muscles with high activities, including gluteus maximus, semitendinosus, Rectus femoris, iliopsoas, vastus lateralis and sartorius, were analyzed, and those muscles with low activities or small muscle tissues were not taken into account. Gluteus maximus has a wide and thick quadrilateral shape, and mainly drives the extension and external rotation of the thigh. Semitendinosus is located at the back of the thigh and helps the extension of the hip joint and bending of the knee joint. Rectus femoris is located in the front of the thigh, whose main function is to extend the knee joint and bend the thigh. Iliopsoas is composed of psoas major muscle and iliacus, which is mainly responsible for the external rotation of the thigh and forward flexion of the pelvis and trunk. The sartorius is flat and banded, and is one of the longest in the leg muscles, starting from the anterior superior iliac spine, passing through the inner side of the knee joint, and finally to the inner side of the upper end of the tibia. The main function of sartorius is for the bending of the hip and knee.
Lower limb muscle activation during outdoor running: differences between sprinters, middle-distance and long-distance runners
Published in Sports Biomechanics, 2021
C. L. Hernández-Stender, F. Molina-Rueda, A. Cuesta-Gómez, I. M. Alguacil-Diego
The pattern of EMG in long-distance runners at initial contact presents low muscle activity in most of the muscles. However, it highlights the highest activity of GMED and RF compared to the other modalities. It could be said that the impact of initial contact would be absorbed mostly by the RF and controlled by the GMED in long-distance runners. GMED muscle acts controlling the vertical displacement of the body’s centre of mass (Lenhart et al., 2014), which seems to be increased at lower speeds (Gil et al., 2005; Heiderscheit et al., 2011); and QA both absorbs and generates power (Novacheck, 1995) at low speed. It is possible that to improve the QA activity is necessary the HAM coactivation. In this sense, semitendinosus has been described as a biarticular muscle that contribute to increase the running economy diminishing GMAX and BF activity for hip extension and hip flexion during the stride in long-distance runners (Tartaruga et al., 2012). Distal muscles showed a high activity that could reflect the GAS function of transferring energy (Nicola & Jewison, 2012) and absorbing impact (Novacheck, 1998; Ounpuu, 1990) and the TA function of controlling the forefoot at heel strike at initial contact (Novacheck, 1998) at low speed. GMAX and BF showed the lower activity of the three modalities. It seems that longer contact times suppose less abrupt movements and shorter joint angles for hip extension (García-Verdugo & Landa, 2005) in long-distance runners.