Biomechanics of Skeletal Muscle 4
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Chapter 9: the Muscular System Module 9.1 Overview of Skeletal Muscles
CHAPTER 9: THE MUSCULAR SYSTEM MODULE 9.1 OVERVIEW OF SKELETAL MUSCLES STRUCTURE OF A SKELETAL MUSCLE • Skeletal muscles are not made of muscle cells alone • Skeletal muscle contains blood vessels that supply muscle cells with oxygen and glucose, and remove wastes, and nerves that coordinate muscle contraction • Skeletal muscle also contains connective tissue (next slide) STRUCTURE OF A SKELETAL MUSCLE . Each individual muscle cell (fiber) is surrounded by thin connective tissue called endomysium (Figure 9.1) . Several (between 10 and 100) muscle cells are bundled together into a fascicle by the connective tissue perimysium . All fascicles that make up a muscle are, in turn, enclosed in an outer fibrous connective tissue wrapping (epimysium) STRUCTURE OF A SKELETAL MUSCLE . Interconnected connective tissues taper down and connect to tendons or other connective tissues; attach muscle to bone or other structure to be moved . Example of Structure-Function Core Principle; makes sure muscle pulls as a unit even if some muscle cells are not pulling with same strength as others STRUCTURE OF A SKELETAL MUSCLE • Motor unit – describes motor neuron-muscle cell interaction; example of Cell-Cell Communication Core Principle . Consists of a single motor neuron and all muscle cells it connects to . Some motor units have only a few muscle cells, whereas others have many . Fewer muscle cells in a motor unit = more precise movements of that muscle when it contracts STRUCTURE OF A SKELETAL MUSCLE Shape, size, placement, and arrangement of fibers in a skeletal muscle contribute to function of that muscle; form follows function (Figures 9.2, 9.3; Table 9.1) STRUCTURE OF A SKELETAL MUSCLE Fascicles and Muscle Shapes • Fascicles – bundles of muscle cells whose specific arrangement affects both appearance and function of whole skeletal muscle • Following are different arrangements in which fascicles are found in human body (Figure 9.2) 1 STRUCTURE OF A SKELETAL MUSCLE Fascicles and Muscle Shapes (continued): . -
Mathematical Model of Pennate Muscle (LIF043-15)
CORE Metadata, citation and similar papers at core.ac.uk Provided by Lodz University of Technology Repository Mathematical model of pennate muscle (LIF043-15) Wiktoria Wojnicz, Bartłomiej Zagrodny, Michał Ludwicki, Jan Awrejcewicz, Edmund Wittbrodt Abstract: The purpose of this study is to create a new mathematical model of pennate striated skeletal muscle. This new model describes behaviour of isolated flat pennate muscle in two dimensions (2D) by taking into account that rheological properties of muscle fibres depend on their planar arrangement. A new mathematical model is implemented in two types: 1) numerical model of unipennate muscle (unipennate model); 2) numerical model of bipennate muscle (bipennate model). Applying similar boundary conditions and similar load, proposed numerical models had been tested. Obtained results were compared with results of numerical researches by applying a Hill-Zajac muscle model (this is a Hill type muscle model, in which the angle of pennation is taken into consideration) and a fusiform muscle model (a muscle is treated as a structure composed of serially linked different mechanical properties parts). 1. Introduction The human movement system consists of striated skeletal muscles that have different architectures. Among these muscles are fusiform muscles and pennate muscles (unipennate muscles, bipennate muscles and multipennate muscles) [7]. The fusiform muscle fibers run generally parallel to the muscle axis (it is line connecting the origin tendon and the insertion tendon). The unipennate muscle fibers run parallel to each other but at the pennation angle to the muscle axis [6]. The bipennate muscle consists of two unipennate muscles that run in two distinct directions (i.e. -
Skeletal Muscle Physiology
This document was created by Alex Yartsev ([email protected]); if I have used your data or images and forgot to reference you, please email me. Skeletal Muscle Physiology First of all, which muscle is which - Skeletal muscle: o Well-developed cross-striations o Does not contract in absence of a nerve stimulus o The individual muscle fibers DO NOT connect functionally or anatomically (i.e. they don’t form a single sheet of cells, and one fiber’s action potential wont get transmitted to the next) o Generally, skeletal muscle is under voluntary control - Cardiac muscle: o Also has cross-striations o Is functionally syncytial: cells are connected well enough to conduct action potentials to one another o Can contract on its own, without stimulus (but this is under some control via the autonomic nervous system, which modulates its activity) - Smooth muscle: o Has no cross-striations o Two broad types: . VISCERAL or “unitary” smooth muscle: Functionally syncytial, action potentials propagate from cell to cell Contains pacemakers which discharge irregularly, but remains under control of the autonomic nervous system Found in most hollow viscera . MULTI-UNIT SMOOTH MUSCLE Found in the eye and some other locations Does NOT activate spontaneously SKELETAL MUSCLE ORGANIZATION - Each muscle is a bundle of fibers - Each fiber is a long, multinucleated single cell - Each fiber is surrounded by a SARCOLEMMA- the cell membrane - There are NO SYNCYTIAL BRIDGES between the cells. When one cell goes off, the others don’t follow. TRANSVERSE TUBULES: T-tubules, invaginations of SARCOLEMMA: the muscle cell membrane the sarcolemma, they form part of the T-system; the space inside is an extension of the extracellular space. -
Back-To-Basics: the Intricacies of Muscle Contraction
Back-to- MIOTA Basics: The CONFERENCE OCTOBER 11, Intricacies 2019 CHERI RAMIREZ, MS, of Muscle OTRL Contraction OBJECTIVES: 1.Review the anatomical structure of a skeletal muscle. 2.Review and understand the process and relationship between skeletal muscle contraction with the vital components of the nervous system, endocrine system, and skeletal system. 3.Review the basic similarities and differences between skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue. 4.Review the names, locations, origins, and insertions of the skeletal muscles found in the human body. 5.Apply the information learned to enhance clinical practice and understanding of the intricacies and complexity of the skeletal muscle system. 6.Apply the information learned to further educate clients on the importance of skeletal muscle movement, posture, and coordination in the process of rehabilitation, healing, and functional return. 1. Epithelial Four Basic Tissue Categories 2. Muscle 3. Nervous 4. Connective A. Loose Connective B. Bone C. Cartilage D. Blood Introduction There are 3 types of muscle tissue in the muscular system: . Skeletal muscle: Attached to bones of skeleton. Voluntary. Striated. Tubular shape. Cardiac muscle: Makes up most of the wall of the heart. Involuntary. Striated with intercalated discs. Branched shape. Smooth muscle: Found in walls of internal organs and walls of vascular system. Involuntary. Non-striated. Spindle shape. 4 Structure of a Skeletal Muscle Skeletal Muscles: Skeletal muscles are composed of: • Skeletal muscle tissue • Nervous tissue • Blood • Connective tissues 5 Connective Tissue Coverings Connective tissue coverings over skeletal muscles: .Fascia .Tendons .Aponeuroses 6 Fascia: Definition: Layers of dense connective tissue that separates muscle from adjacent muscles, by surrounding each muscle belly. -
Structure of a Skeletal Muscle
STRUCTURE OF A SKELETAL MUSCLE Skeletal muscles are not made of muscle cells alone • Skeletal muscle contains blood vessels that supply muscle cells with oxygen and glucose, and remove wastes, and nerves that coordinate muscle contraction • 1 § Each individual muscle cell (fiber) is surrounded by the _____________ § Several muscle cells are bundled together into a _________ by the _____________ § All fascicles that make up a muscle are, in turn, enclosed by the _____________ § Interconnected connective tissues taper down and connect to tendons or other connective tissues; attach muscle to bone or other structure to be moved Figure 9.1 Position and structure of a skeletal muscle. 2 FUNCTIONS OF SKELETAL MUSCLES • Muscle contractions are involved in more than just movement of bones at a joint: § § Contraction of diaphragm muscle is a vital function associated with respiratory system § _________________ – sitting, standing, holding head upright § Skeletal muscles attached to facial skin allow for facial expression; muscles in throat assist with swallowing § Sphincters composed of skeletal muscle allow conscious control over opening and closing of body openings § Support of soft tissue – abdominal walls, pelvic floor 3 • Functional groups of muscles: generally takes cooperation of several individual muscles working as a group to perform a movement or action § __________________ provide most force for a given muscle action § _____________have opposite action of agonist; allows for modulation and control of agonist movement § _____________aid agonists by supplying supplemental force, minimizing unwanted movement, and by helping to stabilize joints § _____________also provide stabilizing force that anchors a bone; protection from injury due to unnecessary movements Figure 9.3 Functional groups of muscles. -
Muscle-Tendon Length and Force Affect Human Tibialis Anterior Central
Muscle-tendon length and force affect human tibialis PNAS PLUS anterior central aponeurosis stiffness in vivo Brent James Raiteria,b,1, Andrew Graham Cresswella, and Glen Anthony Lichtwarka aCentre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, St. Lucia, QLD 4072, Brisbane, Australia; and bHuman Movement Science, Faculty of Sport Science, Ruhr-University Bochum, 44801 Bochum, Nordrhein-Westfalen, Germany Edited by Silvia Salinas Blemker, University of Virginia, Charlottesville, VA, and accepted by Editorial Board Member C. O. Lovejoy February 21, 2018 (received for review July 20, 2017) The factors that drive variable aponeurosis behaviors in active versus considering stress–strain relationships of tendinous tissues estimated passive muscle may alter the longitudinal stiffness of the aponeuro- from muscle fiber/fascicle length changes (7, 10, 24, 25). However, sis during contraction, which may change the fascicle strains for a there is a growing body of literature to suggest that the SEE stiffness given muscle force. However, it remains unknown whether these is dependent on contractile conditions (13, 15, 26–28), as well as factors can drive variable aponeurosis behaviors across different suggestions that the aponeurosis cannot be a simple in-series spring muscle-tendon unit (MTU) lengths and influence the subsequent (29). The potential variable nature of aponeurosis elastic function is fascicle strains during contraction. Here, we used ultrasound and likely to impact our understanding of how this tissue contributes to elastography techniques to examine in vivo muscle fascicle behavior energy savings and/or power amplification during animal or human and central aponeurosis deformations of human tibialis anterior (TA) locomotion (30), as well as our understanding of the strains expe- during force-matched voluntary isometric dorsiflexion contractions rienced by muscles and connective tissues during such contractions at three MTU lengths. -
The Ubiquitin Proteasome System in Neuromuscular Disorders: Moving Beyond Movement
International Journal of Molecular Sciences Review The Ubiquitin Proteasome System in Neuromuscular Disorders: Moving Beyond Movement 1, , 2, 3,4 Sara Bachiller * y , Isabel M. Alonso-Bellido y , Luis Miguel Real , Eva María Pérez-Villegas 5 , José Luis Venero 2 , Tomas Deierborg 1 , José Ángel Armengol 5 and Rocío Ruiz 2 1 Experimental Neuroinflammation Laboratory, Department of Experimental Medical Science, Lund University, Sölvegatan 19, 221 84 Lund, Sweden; [email protected] 2 Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla/Instituto de Biomedicina de Sevilla-Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Sevilla, Spain; [email protected] (I.M.A.-B.); [email protected] (J.L.V.); [email protected] (R.R.) 3 Unidad Clínica de Enfermedades Infecciosas, Hospital Universitario de Valme, 41014 Sevilla, Spain; [email protected] 4 Departamento de Especialidades Quirúrgicas, Bioquímica e Inmunología, Facultad de Medicina, 29071 Universidad de Málaga, Spain 5 Departamento de Fisiología, Anatomía y Biología Celular, Universidad Pablo de Olavide, 41013 Sevilla, Spain; [email protected] (E.M.P.-V.); [email protected] (J.Á.A.) * Correspondence: [email protected] These authors contributed equally to the work. y Received: 14 July 2020; Accepted: 31 August 2020; Published: 3 September 2020 Abstract: Neuromuscular disorders (NMDs) affect 1 in 3000 people worldwide. There are more than 150 different types of NMDs, where the common feature is the loss of muscle strength. These disorders are classified according to their neuroanatomical location, as motor neuron diseases, peripheral nerve diseases, neuromuscular junction diseases, and muscle diseases. Over the years, numerous studies have pointed to protein homeostasis as a crucial factor in the development of these fatal diseases. -
Regional Heterogeneity in Muscle Fiber Strain: the Role of Fiber Architecture
UC Irvine UC Irvine Previously Published Works Title Regional heterogeneity in muscle fiber strain: the role of fiber architecture. Permalink https://escholarship.org/uc/item/125212ss Authors Azizi, E Deslauriers, Amber R Publication Date 2014 DOI 10.3389/fphys.2014.00303 Peer reviewed eScholarship.org Powered by the California Digital Library University of California PERSPECTIVE ARTICLE published: 12 August 2014 doi: 10.3389/fphys.2014.00303 Regional heterogeneity in muscle fiber strain: the role of fiber architecture E. Azizi* and Amber R. Deslauriers Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, USA Edited by: The force, mechanical work and power produced by muscle fibers are profoundly affected Emma F.Hodson-Tole, Manchester by the length changes they undergo during a contraction. These length changes are in turn Metropolitan University, UK affected by the spatial orientation of muscle fibers within a muscle (fiber architecture). Reviewed by: Therefore any heterogeneity in fiber architecture within a single muscle has the potential Boris Prilutsky, Georgia Institute of Technology, USA to cause spatial variation in fiber strain. Here we examine how the architectural variation Glen Lichtwark, The University of within a pennate muscle and within a fusiform muscle can result in regional fiber strain Queensland, Australia heterogeneity. We combine simple geometric models with empirical measures of fiber *Correspondence: strain to better understand the effect of architecture on fiber strain heterogeneity. We E. Azizi, Department of Ecology and show that variation in pennation angle throughout a muscle can result in differences in Evolutionary Biology, 321 Steinhaus Hall, University of California Irvine, fiber strain with higher strains being observed at lower angles of pennation. -
Variable Gearing in Pennate Muscles
Variable gearing in pennate muscles Emanuel Azizi*, Elizabeth L. Brainerd, and Thomas J. Roberts Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 Edited by Ewald R. Weibel, University of Bern, Bern, Switzerland, and approved December 3, 2007 (received for review September 27, 2007) Muscle fiber architecture, i.e., the physical arrangement of fibers within a muscle, is an important determinant of a muscle’s me- chanical function. In pennate muscles, fibers are oriented at an angle to the muscle’s line of action and rotate as they shorten, becoming more oblique such that the fraction of force directed along the muscle’s line of action decreases throughout a contrac- tion. Fiber rotation decreases a muscle’s output force but increases output velocity by allowing the muscle to function at a higher gear ratio (muscle velocity/fiber velocity). The magnitude of fiber rota- tion, and therefore gear ratio, depends on how the muscle changes shape in the dimensions orthogonal to the muscle’s line of action. Here, we show that gear ratio is not fixed for a given muscle but decreases significantly with the force of contraction (P < 0.0001). We find that dynamic muscle-shape changes promote fiber rota- tion at low forces and resist fiber rotation at high forces. As a result, gearing varies automatically with the load, to favor velocity output during low-load contractions and force output for contractions against high loads. Therefore, muscle-shape changes act as an automatic transmission system allowing a pennate muscle to shift Fig. 1. A 17th century geometric examination of muscle architecture (5). -
Summation of Motor Unit Force in Passive and Active Muscle Thomas G
ARTICLE Summation of Motor Unit Force in Passive and Active Muscle Thomas G. Sandercock Department of Physiology, Northwestern University Medical School, Chicago, IL SANDERCOCK, T.G. Summation of motor unit force in passive and active muscle. Exerc. Sport Sci. Rev., Vol. 33, No. 2, pp. 76–83, 2005. Nonlinear summation of force has been observed between motor units. The complex structure of muscle suggests many reasons why this could happen. When large portions of the muscle are active, however, the nonlinearities are small, and generally explained by stretch of the common elasticity. This suggests that the type of nonlinearity observed between motor units may not be physiologically significant. Key Words: motor unit, summation, model, architecture, nonlinear INTRODUCTION the width of the length–tension curve will remain the same. This simple example suggests that the force from separate Because of the complex structure of muscle, the transmission motor units might sum linearly in a muscle with parallel of force from a single fiber to the action of the whole muscle fibers. is poorly understood. The force produced by the activation of two motor units, for example, can be more (superadditive) or less (subadditive) than the force exerted by the sum of the Force Transmission Within a Muscle two motor units when they are activated alone. There are many reasons why the force of motor units may not sum The actual structure of even the simplest muscle is more linearly. This review examines the theoretical expectations complex than the serial or parallel arrangements described and the experimental literature on the summation of motor above. -
Motor Unit Number Estimation: a Technology and Literature Review Clifton L
AANEM TECHNOLOGY REVIEW MOTOR UNIT NUMBER ESTIMATION: A TECHNOLOGY AND LITERATURE REVIEW CLIFTON L. GOOCH, MD,1 TIMOTHY J. DOHERTY, MD, PhD,2,3,4 K. MING CHAN, MD,5 MARK B. BROMBERG, MD, PhD,6 RICHARD A. LEWIS, MD,7 DAN W. STASHUK, PhD,8 MICHAEL J. BERGER, MD, PhD,9,10 MICHAEL T. ANDARY, MD,11 and JASPER R. DAUBE, MD12 1 Department of Neurology, University of South Florida, Tampa, Florida, USA 2 Department of Physical Medicine and Rehabilitation, University of Western Ontario, London, Ontario, Canada 3 Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada 4 Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada 5 Division of Physical Medicine and Rehabilitation/Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada 6 Department of Neurology, University of Utah, Salt Lake City, Utah, USA 7 Department of Neurology, Cedars-Sinai, Los Angeles, California USA 8 Systems Design Engineering, University of Waterloo, Waterloo, Ontario, Canada 9 School of Kinesiology, University of Western Ontario, London, Ontario, Canada 10 Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada 11 College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan, USA 12 Department of Neurology, Mayo Clinic, Rochester Minnesota, USA Accepted 27 August 2014 ABSTRACT: Introduction: Numerous methods for motor unit inception of modern neuromuscular physiology. number estimation (MUNE) have been developed. The objective of this article is to summarize and compare the major methods The first motor unit number estimation (MUNE) and the available data regarding their reproducibility, validity, appli- method evolved from routine motor nerve conduc- cation, refinement, and utility. -
Effect of Strength Training on Muscle Architecture (Review) Javid Mirzayev Mediland Hospital, Republic of Azerbaijan Tula State University, Russian Federation
60 SPORTO MOKSLAS / 2017, Nr. 1(87), ISSN 1392-1401 / eISSN 2424-3949 Sporto mokslas / Sport Science 2017, Nr. 1(87), p. 60–64 / No. 1(87), pp. 60–64, 2017 DOI: http://dx.doi.org/10.15823/sm.2017.9 Effect of strength training on muscle architecture (review) Javid Mirzayev Mediland hospital, Republic of Azerbaijan Tula State University, Russian Federation Summary Muscle architecture is among the most important factors that determine the function of muscles. Muscle architecture is the “organizer” of muscle fibres in muscle strength generating relative line and includes several important aspects: 1) normalized fibre length, 2) pennation angle, and 3) physiological cross-sectional area. Architectural changes in muscles immediately respond to resistance training, but it is not entirely dependent on muscle contraction mode. To the date, we very poorly understand architectural parameters for each muscle; thus, further studies are needed to explore the architecture of individual muscles and further to expand our understanding of this important organizer of muscle fibres. The purpose of the article is to examine the relationship between strength training and muscle structures. Method chosen: analysis of scientific literature. Results and conclusions. In general, contemporary scientific research confirms in the 80-ies identified circumstantial evidence in favour of muscle architecture changes with the help of strength training. Hypertrophy of the muscle increases the angles of pennate muscles. The more muscle hypertrophy evolves, the less specific voltage occurs. Increased muscle volume in the eccentric training is closely related to increasing length of the beams, but pennation angle is not changed. The level of tension is responsible for the change in maximal voluntary contraction.