Masseter muscle is partly concealed, anteriorly, by the superficial portion. Posteriorly, it is covered by the parotid gland. Along with the other three muscles of mastication (temporalis, medial pterygoid, and lateral pterygoid), the masseter is innervated by the anterior division of the mandibular division (V3) of the trigeminal nerve. The innervation pathway is: gyrus precentralis > genu capsula interna > nucleus motorius nervi trigemini > nervus trigeminus > nervus mandibularis > musculus masseter. The action of the muscle during bilateral contraction of the entire muscle is to elevate the mandible, raising the lower jaw. Elevation of the mandible occurs during the closing
Effect of spaceflight on the human body to best counteract the bone and muscle atrophy experienced by astronauts in microgravity environments for prolonged periods of time. The Human Research Program's Human Health Countermeasures Element chartered the Digital Astronaut Project to investigate targeted questions about exercise countermeasure regimes. NASA is focusing on integrating a model of the advanced Resistive Exercise Device (ARED) currently on board the International Space Station with OpenSim musculoskeletal models of humans exercising with the device. The goal of this work is to use inverse dynamics to estimate joint torques and muscle forces resulting from using the ARED, and thus more accurately prescribe exercise regimens