What Is the Purpose of the Muscular System?


The human body contains more than 650 skeletal muscles, according to Gary Thibodeau and Kevin Patton in their book, “Structure and Function of the Body.” Muscles control every movement in your body, from pushing food through your digestive system to helping you lift a baby. In addition to movement, your muscles also help you produce heat and maintain posture.

Smooth Muscle

Smooth muscle, often referred to as involuntary muscle or visceral muscle, makes up many of your internal organs. You have no physical control over this type of muscle. Your brain controls them without any conscious effort from you, according to KidsHealth.org. Smooth muscles control the movement of blood through the blood vessels, the movement of food through the digestive system, the passage of urine to the bladder, the contraction of a the uterus to have a baby, the ability of the eyes to focus and many other automatic functions of the body.

Cardiac Muscle

Cardiac muscle makes up the walls of the heart, according to Tibodeau and Patton. This myocardial muscle contracts and relaxes the heart to allow blood to pump throughout the body. Similar to smooth muscle, you have no control over how fast your heart muscle pumps, though you can accelerate heart rate through exercise.

Skeletal Muscle

Skeletal muscle makes up approximately 40 percent of the average adult’s body weight, according to Tibodeau and Patton. Your skeletal muscles work with your bones to give you the power and strength required for good posture and for moving things. In addition to movement and posture, your muscles help maintain your body’s temperature. The contraction of your skeletal muscles helps produce the majority of the heat required to maintain your body’s temperature.

Types of Skeletal Muscle Contraction

Skeletal muscles can contract in several ways to produce movement and power. Concentric contractions shorten a muscle and allow you to lift something, according to the University of California-San Diego. Eccentric contractions lengthen a muscle, allowing you to put an object down. Both contractions help in walking. During isometric contractions, a muscle stays at the same length while being used to apply force. This type of contraction occurs when you apply force to something that does not move.

Skeletal Muscle Movements

The skeletal muscles provide the ability to move your body the way you want. The main types of movements include flexion, extension, abduction, adduction, rotation, supination, pronation, dorsiflexion, plantar flexion, inversion and eversion, according to Tibodeau and Patton. Flexion and extension describe movements such as bending or straightening your arm, respectively. Abduction and adduction refer to moving the arm away from your side or toward your side, respectively. Rotation involves movement around a longitudinal axis, like when you turn your head from side to side. Supination and pronation involve the turning of your palm to face the ceiling or the floor, respectively. Dorsiflexion and plantar flexion involve bringing your toes toward your head or pointing them, respectively. Finally inversion and eversion involve bending your ankle to bring the bottom of your foot toward midline or away from midline, respectively.

About this Author

Kimberly Wonderly has a Bachelor of Science degree in exercise science and has worked as a personal trainer for six years. Wonderly has also taken many child development classes, while running a daycare out of her home for three years. She wrote for the “Rocket” at Slippery Rock University for two years while attending college.