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Mechanically Induced Periarticular and Neuromuscular Problems
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
The concept that the primary function of ligaments is to restrain the extremes of joint motion is inconsistent with good engineering design principles. The frequency of ligamentous rupture eloquently demonstrates that ligaments are poorly constructed for this function. In dynamic circumstances, when forces are high, what limits extreme joint motion is muscular action. In passive circumstances, when the forces are low (7), the ligaments can effectively act as checks. Ligaments have an equally important function as proprioceptive receptors (8). Stretch receptors in ligaments provide necessary afferent signals to the involuntary neurological pathways to regulate appropriate antagonistic muscle contraction, which can control and limit joint motion (see Chap. 9). This system is made inoperative when the deforming forces are unexpected and there is inadequate time to “get ready”—to set preprogrammed muscular action into play. Under these circumstances ligaments rupture (9).
Human and Biomimetic Sensors
Published in Patrick F. Dunn, Fundamentals of Sensors for Engineering and Science, 2019
Proprioceptors provide a “sense of self,” sensing the spatial position of our limbs, their movement, and the state of their muscles’ tension. They include muscle spindles (see Figure 3.14), Golgi tendon organs (see Figure 3.15), and joint receptors. They sense changes in muscle length, muscle tension, and relative position of bones, respectively. All three sensors are primary afferent nerve endings. Muscle spindles, present within muscle, consist of connective tissue, intrafusal muscle fibers, efferent nerve endings, and two kinds of sensory nerve endings. One kind of sensory ending (group 1a primary) monitors the speed of change in muscle length. Another kind (type II secondary) monitors the steady-state muscle length along with the primary nerve ending. Spindles are arranged in parallel within a muscle. These stretch receptors sense muscle length and changes in length. Golgi tendon organs connect at one end to muscle fibers and at the other end to tendons. Thus, they are in series with the extrafusal muscle fibers. They comprise connective tissue, collagen fibers, and afferent nerve endings. They sense the contraction of muscle but not its extension. The afferent nerve endings of joint receptors respond to changes in the relative position of bones that are linked by flexible joints.
Hearing, Proprioception, and the Chemical Senses
Published in Robert W. Proctor, Van Zandt Trisha, Human Factors in Simple and Complex Systems, 2018
Robert W. Proctor, Van Zandt Trisha
Receptors located within muscle tendons and joints, as well as the skin, provide information about the position of our limbs. This information is called proprioception and, when related to movement, kinesthesis. It plays a fundamental role in the coordination and control of bodily movement. The input for proprioception comes from several types of receptors. Touch receptors lie deep in layers of tissue beneath the skin. Stretch receptors attached to muscle fibers respond to the stretching of the muscles. Golgi tendon organs sensitive to muscle tension are attached to the tendons that connect the muscles to bones. Joint receptors are located in joints and provide information about joint angle. The neurons that carry the information for proprioception travel to the brain by way of the same two pathways as for touch. They also project into the same general area of the somatosensory cortex.
Potential effect of pre-activated muscles under a far-side lateral impact
Published in Traffic Injury Prevention, 2021
María González-García, Jens Weber, Steffen Peldschus
The THUMS TUC-VW AHBM includes 600 curved muscles modeled with 1-D Hill-type elements. Besides, the original material properties of the THUMS TUC, especially the soft tissue materials, have been modified (Yigit 2018) according to available literature data (Song et al. 2007; Van Loocke et al. 2008; Nie et al. 2010; Mattucci et al. 2012). To consider the muscle activation, while keeping the computational time low, the muscles have been clustered into 66 muscle controllers depending on their functionality, e.g., flexors and extensors. Two software packages have been coupled to calculate the muscle activation, namely VPS and SimulationX. The former handles the finite element computation, whereas the latter controls the muscle activation. The muscle control strategy is a closed-loop feedback controller based on the length and the strain rate of the muscle at each time step. This algorithm represents the neuromuscular action of the muscle spindles, which are stretch receptors detecting changes in the length of the muscle. Besides, a parameter to account for the agonist-antagonist relationship has been included (Günther & Runder 2003). Based on the dynamic activation reported in (Hatze 1978), the muscle activation is computed and fed back into the muscle material to calculate the active muscle forces. Nonetheless, the muscle activation is not considered immediately by the contractile element but after the neural delay has been reached.