![]() During forearm flexionâbending the elbowâthe brachioradialis assists the brachialis.Īlthough a number of muscles may be involved in an action, the principal muscle involved is called the prime mover, or agonist. The moveable end of the muscle that attaches to the bone being pulled is called the muscleâs insertion, and the end of the muscle attached to a fixed (stabilized) bone is called the origin. To pull on a bone, that is, to change the angle at its synovial joint, which essentially moves the skeleton, a skeletal muscle must also be attached to a fixed part of the skeleton. Interactions of Skeletal Muscles in the Body The bone connection is why this muscle tissue is called skeletal muscle. The tendons are strong bands of dense, regular connective tissue that connect muscles to bones. To move the skeleton, the tension created by the contraction of the fibers in most skeletal muscles is transferred to the tendons. Explain the major events of a skeletal muscle contraction within a muscle in generating force.Describe how fascicles are arranged within a skeletal muscle.Compare and contrast agonist and antagonist muscles.Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systemsīy the end of this section, you will be able to: The actions of the skeletal muscles will be covered in a regional manner, working from the head down to the toes. This chapter also will describe how skeletal muscles are arranged to accomplish movement, and how other muscles may assist, or be arranged on the skeleton to resist or carry out the opposite movement. If you understand the meaning of the name of the muscle, often it will help you remember its location and/or what it does. The system to name skeletal muscles will be explained in some cases, the muscle is named by its shape, and in other cases it is named by its location or attachments to the skeleton. The focus of this chapter is on skeletal muscle organization. If you recall from your study of the skeletal system and joints, body movement occurs around the joints in the body. The diaphragm is a sheet of skeletal muscle that has to contract and relax for you to breathe day and night. Skeletal muscles are even used during sleep. Think about the things that you do each dayâtalking, walking, sitting, standing, and runningâall of these activities require movement of particular skeletal muscles. Identify the origins and insertions of skeletal muscles and the prime movements. ![]() Identify the skeletal muscles and their actions on the skeleton and soft tissues of the body.Explain the criteria used to name skeletal muscles.Explain the structure and organization of muscle fascicles and their role in generating force.Describe the actions and roles of agonists and antagonists.(credit: Dmitry Yanchylenko)Īfter studying this chapter, you will be able to: Practicing yoga, as pictured here, is a good example of the voluntary use of the muscular system. Movement is one of the most distinctive and easily observed “characteristics of life.Figure 11.1 A Body in Motion The muscular system allows us to move, flex and contort our bodies. Our subject for now, then, is the large mass of skeletal muscle that moves the framework of the body: the muscular system. However, bones and joints cannot move themselves. We have investigated the architectural plan of the skeleton and have seen how its firm supports and joint structures make movement possible. Whereas many different systems of the body have some role in accomplishing movement, it is the skeletal and muscular systems acting together that actually produce most body movements. Such stability often requires movement of the body. S urvival depends on the ability to maintain a relatively constant internal environment. The Big Picture: Skeletal Muscles and the Whole Body, 342 Muscles That Move the Ankle and Foot, 340 Muscles That Move the Wrist, Hand, and Fingers, 329 Muscles Acting on the Shoulder Girdle, 322 Hints on How to Deduce Muscle Actions, 311 Scan this outline before you begin to read the chapter, as a preview of how the concepts are organized.
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