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The following sections provide a basic framework for the understanding of gross human muscular anatomy, with descriptions of the large muscle groups and their actions. The various muscle groups work in a coordinated fashion to control the movements of the human body.
Muscle, contractile tissue found in animals, the function of which is to produce motion. Muscle cells fuel their action by converting chemical energy in the form of adenosine triphosphate (ATP), which is derived from the metabolism of food, into mechanical energy.
skeletal muscle, in vertebrates, most common of the three types of muscle in the body. Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control. Similar to cardiac muscle, however, skeletal ...
Muscle - Structure, Organization, Fibers: Smooth muscle contains spindle-shaped cells 50 to 250 μm in length by 5 to 10 μm in diameter. These cells possess a single, central nucleus. Surrounding the nucleus and throughout most of the cytoplasm are the thick (myosin) and thin (actin) filaments.
The musculoskeletal system (also referred to separately as the muscle system and the skeletal system), composed of the skeletal muscles and bones (with about 206 of the latter in adults), moves the body and protectively houses its internal organs.
The principal types of muscles are striated muscle, in which the filaments are organized in transverse bands as in Figure 2; obliquely striated muscle, in which the filaments are staggered, making the bands oblique (Figure 3); and smooth muscle, in which the filaments are arranged irregularly.
Cardiac muscle differs from skeletal muscle in that it exhibits rhythmic contractions and is not under voluntary control. The rhythmic contraction of cardiac muscle is regulated by the sinoatrial node of the heart, which serves as the heart’s pacemaker.
Human muscle system, the muscles of the human body that work the skeletal system, that are under voluntary control, and that are concerned with movement, posture, and balance. Broadly considered, human muscle—like the muscles of all vertebrates—is often divided into striated muscle, smooth muscle, and cardiac muscle.
Human muscle system - Shoulder Muscles, Joints, Movements: The shoulder is a complex ball-and-socket joint comprising the head of the humerus, the clavicle (collarbone), and the scapula. The shoulder’s main motions are flexion, extension, abduction, adduction, internal rotation, and external rotation.
muscle, Contractile tissue that produces motion for functions, including body movements, digestion, focusing, circulation, and body warmth. It can be classified as striated, cardiac, and smooth or as phasic and tonic (responding quickly or gradually to stimulation, respectively).