China
Africa
Explore chapters and articles related to this topic
A Review of the Technologies and Methodologies Used to Quantify Muscle-Tendon Structure and Function
Published in Cornelius Leondes, Musculoskeletal Models and Techniques, 2001
At the level of the gross muscle, the physiological cross-sectional area (PCSA) is most commonly used to indicate a muscle’s strength, fiber length, orientation, and type to indicate its maximum velocity of shortening.95,117 PCSA is calculated by taking the product of muscle mass and the cosine of the pinnation angle, and dividing by the product of fiber length and muscle density. It is important to note that mass alone does not dictate strength, but rather mass and fiber length do so. A muscle with short fibers oriented at some angle relative to the axis of the muscle-tendon complex will generate greater maximum force than a muscle of similar mass that has longer and fewer fibers. Because muscle fibers are composed of serial arrangements of sarcomeres, fiber length affects shortening velocity. Longer fibers have faster shortening velocities, provided the fiber types are similar.
Tissue Structure and Function
Published in Joseph W. Freeman, Debabrata Banerjee, Building Tissues, 2018
Joseph W. Freeman, Debabrata Banerjee
As a muscle contracts, the Z lines come closer together and the width of the I bands and H zones decrease. There no change in the width of the A band. Conversely, as a muscle is stretched, the width of the I bands and H zones increases, but there is no change in the width of the A band. The shortening of the sarcomeres in a myofibril shortens the myofibril and the muscle fiber that it belongs to. Muscle force is proportional to physiologic cross-sectional area (PCSA), and muscle velocity is proportional to muscle fiber length. PCSA is the sum of the areas of each fiber in the muscle.
Human–Machine Force Interactive Interface and Exoskeleton Robot Techniques Based on Biomechanical Model of Skeletal Muscle
Published in Yuehong Yin, Biomechanical Principles on Force Generation and Control of Skeletal Muscle and their Applications in Robotic Exoskeleton, 2020
Referring to the skeletal muscle contraction mechanism in Chapter 3, the maximum contraction force is proportional to the physiological cross-sectional area (PCSA) of the muscle. Based on Table 4.4, the cross-sectional area of SR and TF is smaller than that of the QF; the maximum isometric contraction force is also smaller. Thus, the influence on knee joint movement is smaller, and their influence can be neglected. The muscles, including the ST, SM, BF and QF (RF, VI, VL, VM) are main actuators considered here.
The influence of model parameters on model validation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Benjamin W. Infantolino, Steph E. Forrester, Matthew T.G. Pain, John H. Challis
For the FDIs from each of the cadaver hands pennation angles were measured in both heads using a standard goniometer. As the length of the fascicles varied between samples all pennation angles were referenced to optimum fiber length, this was achieved using a planimetric model of muscle geometry (Otten 1988). In the planar muscle model muscle area remained constant, mirroring the constant volume requirement in muscle (Baskin and Paolini 1966); to achieve this constraint muscle thickness was assumed to remain constant irrespective of fascicle length and therefore other aspects of muscle geometry could be computed (Figure 2). The mass of each muscle was measured to the nearest 0.01 g immediately after dissection, and then used in combination with fiber length and pennation angle to compute muscle physiological cross-sectional area (PCSA; Narici 1999). External tendon length (LT) and muscle belly length were measured to the nearest 0.5 mm using a standard rule and a stereo dissecting microscope at 5x magnification.
Hamstring musculotendon mechanics of prospectively injured elite rugby athletes
Published in Research in Sports Medicine, 2023
Claire Kenneally-Dabrowski, Nicholas A.T. Brown, Benjamin G. Serpell, Diana Perriman, Wayne Spratford, Ashlee Sutherland, Mark Pickering, Adrian K.M. Lai
Pre-season MRI data were manually segmented using a custom Matlab application, which has been previously used to segment and create 3D reconstructions of cervical spine muscles (Au et al., 2016). Muscle borders were traced on axial slices for all four hamstring muscles and these cross-sectional areas were used to calculate whole muscle volume. Physiological cross-sectional area (PCSA) was then calculated, defined as muscle volume (cm3)/optimal fibre length (cm) (Friederich & Brand, 1990).
Static stretching time required to reduce iliacus muscle stiffness
Published in Sports Biomechanics, 2021
Shusuke Nojiri, Masahide Yagi, Yu Mizukami, Noriaki Ichihashi
The iliopsoas muscle consists of the iliacus and psoas major muscles. The iliacus muscle has greater physiological cross-sectional area (PCSA) and hip flexion moment arm than the psoas major muscle (Blemker & Delp, 2005; Klein Horsman, Koopman, van der Helm, Prosé, & Veeger, 2007). Therefore, increased stiffness or shortening of the iliacus muscle affects hip extension ROM more strongly than similar changes in the psoas major muscle.