Muscle
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella in Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Movement that decreases the angle of a joint, or bends the joint, and brings the bones toward each other is referred to as flexion. For the above example, the biceps brachii flexes the forearm. In contrast, movement that increases the angle of the joint and straightens the joint is referred to as extension. In the previously mentioned example, the triceps brachii acts as an opposing muscle to the biceps brachii. Located on the posterior surface of the arm, the triceps brachii originates on the scapula and the upper portion of the humerus (arm), and inserts on the ulna (the other bone of the forearm), and crosses the elbow joint. However, when it develops tension and shortens, the triceps extends the forearm and straightens the elbow joint. Thus, the triceps brachii causes a movement opposite to that of the biceps brachii. A muscle that works in opposition to another muscle is referred to as an antagonist muscle. An agonist muscle, or prime mover, provides the force for a specific movement. In this case, the agonist muscle is the biceps brachii. Synergist muscles work with the prime movers to achieve the movement. In this case, the synergist muscle is the brachialis muscle of the arm.
Medical Emergency Response Services in the State of Kerala—Evaluation Report
Anne George, Snigdha S. Babu, M. P. Ajithkumar, Sabu Thomas in Holistic Healthcare. Volume 2: Possibilities and Challenges, 2019
In 1971, after release of the National Highway Traffic Safety Administration’s study, “Accidental Death and Disability: The Neglected Disease of Modern Society,” a progress report was published at the annual meeting, by the then president of American Association of Trauma, Sawnie R. Gaston M.D. Dr. Gaston reported the study a “superb white paper” that “jolted and wakened the entire structure of organized medicine.” This report was the “prime mover” and made the “single greatest contribution of its kind to the improvement of EMS.” Since then a concerted effort has been undertaken to improve emergency medical care in the prehospital setting. Such advancements included Dr. R Adams Cowley creating the country’s first statewide EMS program, in Maryland.
The Musculoskeletal System and Its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
Body movement results from the action of a group of muscles rather than a single muscle. Both flexion and extension require a prime mover or agonist pulling in one direction and an antagonist that contracts with an opposite action. Fixation muscles are groups that hold body parts steady to facilitate muscle action. Synergists function by preventing unnecessary muscle action. Functions of some specific muscles are summarized in Table 7.1.
Dance-based exergaming for upper extremity rehabilitation and reducing fall-risk in community-dwelling individuals with chronic stroke. A preliminary study
Published in Topics in Stroke Rehabilitation, 2019
Savitha Subramaniam, Tanvi Bhatt
To record electromyography (EMG) activity, Delsys® Trigno™ surface EMG sensors were used for the paretic UE (sensors placed on the anterior deltoid for shoulder flexion and on the middle deltoid muscle for shoulder abduction). Using a common mode rejection ratio of > 80 db, EMG signals were sampled at 2,000 Hz, and a hardware band-pass was filtered over a bandwidth of 20–450 Hz. Tri-axial accelerometers embedded in these sensors rendered signals sampled at 148.1 Hz about a bandwidth of 50 Hz with an amplitude range of ±1.5 g. Signals were digitally high-pass filtered with a fourth-order zero-lag Butterworth filter (MathWorks, Inc., MATLAB) with a cut-off frequency of 20 Hz, were full-wave rectified, and then were low-pass filtered with a cut-off frequency of 50 Hz for smoothing the EMG data. Smoothing of the acceleration signals was achieved using a fourth order low-pass Butterworth filter with a cut-off frequency of 80 Hz. The acquired signal was later used to compute onset and offset to calculate movement time (MT). A total of six trials per subject were collected and analyzed from the involved prime mover, consisting of three flexion-reaching and three abduction-reaching trials to acquire the variables of interest using a customized MATLAB code.
A versatile approach to determine instantaneous co-activation: Development, implementation and comparison to existing measures
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Daniel Viggiani, Jeff M Barrett, Kayla M Fewster, Jack Callaghan
Firstly, these equations almost exclusively utilize muscle pairs acting in a single plane on a single hinge joint, where one muscle is the ‘prime mover’ and the other provides ‘movement control’ (Falconer and Winter 1985; Rudolph et al. 2000; Lewek et al. 2004). However, there often is no single prime mover in situations where muscles act about multiple anatomical axes (Tsuang et al. 1993) or span multiple joints (Hahn et al. 2014). There have been attempts to overcome this two-muscle limitation. Current modelling approaches (Brookham et al. 2011; Brookham and Dickerson 2014; Le et al. 2018) employ a set of equations to quantify co-contraction between multiple muscles considering the relative size of each muscle of interest. However, one limitation to these approaches is that each muscle must be specified as an agonist or antagonist and the output remains an agonist/antagonist ratio similar to the historical two-muscle equations. Ranavolo et al. (2015) proposed a series of equations determining the dissimilarities between all possible pairs of muscles, correcting for the number of muscles used, and redistributing the output using a sigmoid-shaped weighting term. While this method allows for co-activity measures of multiple muscles without specificity to a plane of motion, there are some drawbacks. In particular, inconsistencies arise at lower levels of muscle activity (<50% maximum voluntary activation (MVA)) since they are mapped to a relatively insensitive region of the sigmoidal curve (Ranavolo et al. 2015). In short, the capability of these methods to accommodate more than two muscles is a recent development.
Validation of an OpenSim full-body model with detailed lumbar spine for estimating lower lumbar spine loads during symmetric and asymmetric lifting tasks
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Erica Beaucage-Gauvreau, William S. P. Robertson, Scott C. E. Brandon, Robert Fraser, Brian J. C. Freeman, Ryan B. Graham, Dominic Thewlis, Claire F. Jones
The poor results for the RA muscles were expected because SO (used in this analysis) penalises antagonist co-contraction (Ait-Haddou et al. 2000). Since the prime-mover muscles during lifting are the trunk extensors (Cresswell and Thorstensson 1994), the effect of the abdominal contractions on the net forces and moments is minimal (Cholewicki et al. 1999). Activation of the antagonist abdominal muscles, and the resulting intra-abdominal pressure (IAP), results in unloading of the lumbar spine during lifting tasks (Stokes et al. 2010); however, the contribution of IAP to increased lumbar spine stiffness and stability is thought to be more significant than its effects on vertebral loading (Cholewicki et al. 1999). The LFB model is not suitable to evaluate the effect of abdominal muscle activity on spine loading, and future work should consider the contributions of RA activations to IAP, and therefore to the loading, stiffness and stability of the lumbar spine.