How Muscles Work

How muscles work.rnThere are three different kinds of muscles in the human body. Smooth muscles which are found in blood vessels, digestive tract, uterus, and bladder. They are involuntary muscles you do not have to think about them for them to work. Cardiac muscles which are found only in the heart, these are also considered involuntary muscles. It's features are endurance and consistency. And last but not least skeletal muscles. rnSkeletal muscles connect to tendons which attach to bones. When a muscle contracts or gets shorter it causes the skeleton, or body parts to move. rnSkeletal muscles are voluntary muscles because we have control over their activity. rnA single muscle is composed of a group of muscle cells, they have the same function and the same insertion and origin. If you could look down the belly of a muscle it would look like several groups of straws, called fascicles arranged in parallel fashion, which are bundled by thin sheets of fiber called fascia. One individual fascicle would be a single muscle cell or fiber, inside the single muscle cell you would find a component called myofibrils. The whole muscle is surrounded by several layers of fasciarnthe fascia join together on the end of the muscle to form the tendon which attaches the muscle to the bone. Lets go deeper into the myofibrils, you would see striations that appear at regular intervals. There is a light band and a dark band which help form the striations, or Z lines. A segment of myofibrils from one Z line to the next is called a sarcomere. One single myofibril can contain up to 100,00 sarcomeres. A sarcomere contains two kinds of protein filaments known as myosin and actin. You may be asking yourself what in the world does this have to do with how muscles work and why should I care? Well, because muscle contraction depends on the interaction between myosin and actin. Myosin have a long fibrous tale and are thicker and are centrally located with in the sarcomeres. Actin are thinner and are structurally linked to the Z line. Remember the light and dark bands? Can you see how the mysoin and actin would create that affect? A muscle contracts when sarcomeres shorten, the thick mysoin make contact with the thin actin forming a cross bridge between the two filaments causing the myosin tail to bend in towards itself this pulls the actin in towards the sarcomeres. With thousands of myosin cross bridges shortening together the result is a sliding movement of the thin filaments relative to the thick ones and a shortening sarcomere. With hundreds and thousands of sarcomeres shortening, individual muscle cells and eventually the whole muscle shorten as well. Also known as a contraction. However, this must be initiated from somewhere. A skeletal muscle cell is activated by a nerve called a motor neuron. This activation increases the concentration of calcium near the myosin and actin. The concentration of calcium induces contraction the absence inhibits contraction, when stimulation of a muscle cell ceases contraction ends and the myosin and actin are no longer in contact.rnThis is a very basic physiology lessons on how muscle contraction. My goal is to give you a general idea and then build on that to help explain how massage helps.