Oct. 22, 2020 | The muscles of the human body play an extremely important role in our daily functions, handling such things as pushing food along the digestive system, pumping blood through the body, focusing the eyes and controlling the width of arteries. There are three types of muscles, the voluntary muscles of the skeletal system, involuntary smooth muscles and involuntary cardiac muscles, all of which can be excited by a nerve or a stimulus. Because there are more than 600 muscles in the body, accounting for about half of a human being’s weight, it’s important to understand how muscles work and how to recognize any potential problems with them. Muscles are attached to bones with tendons, special tissues of connective fibers. Ligaments, also made up of tough connective tissue, connect bone to bone. The brain sends a message to the muscles, telling them to move, through the spinal cord and the spinal nerves, before finally reaching the muscle.

Oct. 22, 2020 | The body’s skeletal muscles vary in shape and strength. The muscles that surround the spine are the most powerful. The muscles on the front forearm allow us to make a fist and bend our fingers. In each of your shoulders is a deltoid, which helps you move every which way, whether you’re swinging a bat or simply lifting an item. The quadriceps muscle, the big, bulky muscle in the front of the thigh, allows us to straighten our knees. The hamstring muscle on the back of the thigh allows us to bend our knees and the muscles in the shin of the leg allow us to bend our ankles upward, with the calf muscles allowing us to bend our ankles downward. All of these muscles are required to perform such rituals as walking, writing and eating. There are a number of other important skeletal muscles, many of which perform their duties with little attention. The neck, back, chest and abdomen muscles help move the spine as well as protecting the organs in our chest and stomach.

Oct. 22, 2020 | An injury to a muscle is usually the result of overexertion or a sudden pull or twist. A muscle strain is when the muscle’s fibers are damaged, with bleeding inside the muscle causing tenderness and swelling. Strains can occur due to constant repetition of a certain movement, particularly if it is performed incorrectly. Treating a strain usually involves short-term immobilization, physical therapy and anti-inflammatory drugs. A muscle tear is when a large number of muscle fibers are torn, causing severe pain and swelling. Severe bleeding may result in the formation of a blood clot, requiring surgery to repair the tear. Tendonitis, which is inflammation of a tendon, can happen when stretching or repetitive movement causes swelling. When a tendon tears, damage is so severe that it separates it from the bone. A tear can result from lifting too much weight. Minor tendon tears are treated with immobilization and physical therapy but more serious tears require surgery.

Oct. 22, 2020 | The movements your muscles make are coordinated and controlled by the brain and nervous system. The involuntary muscles are controlled by structures deep within the brain and the upper part of the spinal cord called the brain stem. The voluntary muscles are regulated by the parts of the brain known as the cerebral motor cortex and the cerebellum. When you decide to move, the motor cortex sends an electrical signal through the spinal cord and peripheral nerves to the muscles, causing them to contract. The motor cortex on the right side of the brain controls the muscles on the left side of the body and vice versa. The cerebellum coordinates the muscle movements ordered by the motor cortex. Sensors in the muscles and joints send messages back through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it’s in. This feedback results in smooth, coordinated motion.

Oct. 22, 2020 | Even when you sit perfectly still, there are muscles throughout your body that are constantly moving. Muscles enable your heart to beat and your blood vessels to help regulate the pressure and flow of blood through your body. When we smile and talk, muscles are helping us communicate, and when we exercise, they help us stay fit and healthy. Muscles move body parts by contracting and then relaxing. Your muscles can pull bones, but they can’t push them back to their original position. So they work in pairs of flexors and extensors. The flexor contracts to bend a limb at a joint. Then, when you’ve completed the movement, the flexor relaxes and the extensor contracts to extend or straighten the limb at the same joint. For example, the biceps muscle, in the front of the upper arm, is a flexor, and the triceps, at the back of the upper arm, is an extensor. When you bend at the elbow, the biceps contracts. Then the biceps relaxes and the triceps contracts to straighten the elbow.