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Parts of the Muscular System

The muscular system is the body's network of tissues that controls movement both of the body and within it. The muscular system generates movement by the contraction and relaxation of muscles. Muscles account for more than half of the body's mass. There are three types of muscles: skeletal, cardiac and smooth. These muscles are either voluntary or involuntary.

  1. Skeletal Muscle

    • According to besthealth.com, there are more than 600 skeletal muscles in the human body. Skeletal muscles are attached to bones and are typically under conscious control for locomotion, facial expressions, posture and other body movements. Skeletal muscle is striated, meaning that the fibers in these muscles are aligned in parallel bands or ridges. Skeletal muscles are attached to the bones by tendons, which are tough and fibrous.

    Smooth Muscle

    • Unlike skeletal muscles, which are attached to bone, smooth muscles are found all over the body in places such as organs and blood vessels. An important function of smooth muscle is creating wave-like contractions known as peristalsis. Peristalsis is required by the body to perform vital actions, such as digestion and nutrient transport. Besthealth.com explains that any action that the body performs without conscious thought is done by smooth muscle contractions.

    Cardiac Muscle

    • Like skeletal muscles, cardiac muscle is composed of striated muscle. Cardiac muscles can only be found in the heart and compose the material known as the atria and ventricles, or heart walls. Cardiac muscles are controlled by the body's autonomic nervous system, making them involuntary muscles.

    Flexor vs Extensor Muscles

    • According to scienceclarified.com, the flexing (contracting) of one muscle is balanced by a lengthening (relaxation) of its paired muscle or a group of muscles. The opposite movements of these muscles allow for joints in the body to be open or closed. Flexor muscles contract, causing the joint to close. Extensor muscles contract, causing the joint to open. An example is the bicep and triceps relationship. When the bicep flexes, the triceps relax and vice versa.

    Muscle Fibers

    • There are two types of muscle fibers: fast-twitch and slow-twitch. According to besthealth.com, fast-twitch fibers are used during anaerobic exercise, while slow-twitch fibers are used during aerobic exercise. Fast-twitch muscles provide short bursts of strength or speed, although they fatigue quickly. Slow-twitch muscles provide an average amount of energy over an extended period of time.

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