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Muscular work
Published in Karl H.E. Kroemer, Fitting the Human, 2017
Muscles usually appear in pairs: one muscle turns a bone around an articulation in one direction while the other muscle turns the opposite way. The elbow provides a good example: here, the pull of the biceps muscle reduces the elbow angle while the triceps pull increases it, as illustrated in Figure 3.4. As the name triceps indicates, this muscle has three heads with three attachments: one reaches across the shoulder joint to the shoulder blade while the other two heads attach to the humerus (the long bone inside the upper arm). The biceps has two heads with two attachments. Co-contraction
Designing for Upper Torso and Arm Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Elbow flexion/extension as shown in Figure 4.40 begins with the arm at the side in the anatomic position (thumb pointed laterally and palm facing forward). The elbow, held at the body’s side, bends and the forearm moves in a sagittal plane, approximately 150 degrees until the forearm presses against the biceps—the primary muscle acting to flex the joint. If the palm is facing toward the body when the elbow bends, the brachioradialis—in the forearm—helps to complete the motion. The triceps acts to extend or straighten the elbow and the forearm returns to the side of the body.
Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Musculus triceps brachii is a voluminous muscle and has three heads, a long head and two short heads. Insertion: The long head (caput lon- gum) origin insertion is on infraglenoid tubercle of the scapula and adheres to shoulder articulation through the capsular joint. The lateral head (caput laterale) origin insertion is on the septum intermuscular brachial lateral and on the posterior part of the humerus above the spiral groove where the radial nerve is located. The medial head (caput mediale) origin insertion is on the posterior part of the humerus below the spiral groove.
Influence of type of MVC test on electromyography measures of biceps brachii and triceps brachii
Published in International Journal of Occupational Safety and Ergonomics, 2018
Danuta Roman-Liu, Paweł Bartuzi
Muscles can act as agonists or antagonists depending on the exerted external force. Some muscles stabilize a given posture when external force is exerted by other muscles, e.g., when handgrip force is exerted, arm muscles stabilize the upper limb posture. MVC tests are performed in specific force activities to produce maximum force in an agonistic muscle [10]. However, in addition to the tested muscles, other muscles, including antagonistic ones, are also activated during those tests. It can be supposed that antagonistic muscles in isometric conditions can be relaxed. A question arises if antagonistic muscles have the same characteristics in time and frequency domains like muscles during relaxation. When considering arm muscles, biceps brachii (BB) produces flexion at the elbow. Triceps brachii (TB) extends the elbow. TB is, therefore, an antagonist of BB in flexion. BB is an antagonist of TB in elbow extension.