The Musculatory System

The musculatory system is important because it allows the skeleton of the body to move. The muscles also play other important roles such as giving form to the body, regulating the body's temperature, and controlling the blood flow of the body. There are three types of muscle tissue: cardiac, smooth, and skeletal.





Cardiac muscle is muscle tissue that is used in the heart. The cardiac muscle tissue is very strong and it contracts automatically under the influence of the sinoatrial node of the heart itself, without the control of the brain.

Smooth muscle can be found in the walls of blood vessels and digestive passageways such as the esophagus and the small and large intestines. It functions by providing a series of wavelike contractions known as peristalsis. Smooth muscle contraction is regulated by the autonomic part of the nervous system, meaning that the contractions cannot be controlled by conscious thought.

Skeletal muscle, also called striated muscle, is the type of muscle tissue that makes up all of the muscles attached to the skeleton and allow for its movement. All skeletal muscles have an origin and an insertion, the places on the skeleton where the muscle is attached. The insertion of a muscle is the bone which the muscle will move when it contracts. The muscle is actually connected to the bone by a strong bundle of connective tisue known as a tendon. Each muscle also has a section called the body, which is the part of the muscle that contracts to make that section of the skeleton move. This is the part of the muscle that contains the actual muscle fibers.

Muscle fibers are actually cells which each run the entire length of the muscle. They contain bound groups of myofibrils which in turn contain bound groups of microfilaments. Myofilaments are made of either actin or myosin, the two proteins that cause the contraction of myofibrils. As the myofilamets are drawn across each other, the myofibril contracts. This contraction is generated by the spread of an action potential, or change in membrane polarity throughout the muscle. Depending on the strength of the action potential, a different number of muscle fibers will be stimulated, but those that are stimulated contract fully. There is no partial contraction of muscle fibers. It is the ability to contract different numbers of fibers that allows the "graded response" of our muscles.

Major Skeletal Muscles

written by Matt Richards