The Muscular System

An Overview: The human body is made up of several main systems, one of which is the muscular system. They are responsible for more than 40 percent of a person's total body weight. These muscles are controlled by the nervous system. Some are involuntarily controlled, meaning they contract and relax without thought. Other muscles are voluntarily controlled, meaning that we must make them contract and relax. There are a few major components of the muscular system. In this section you will need to understand how muscles work in different physical activities. To show your understanding you will need to know the major muscle groups, the types of muscle and how they attach to the skeleton and finally how these muscles create movement.

Muscles to remember: (Skeletal muscles) pectorals trapezius abdominals deltoids latisimus dorsi triceps quadriceps biceps gluteus maximus (gluteals) hamstrings gastrocnemius

3 TYPES OF MUSCLE Voluntary (Skeletal muscle) - These muscles make up the majority of the muscle amount in your body and help to give your body its shape. - They are attached to your skeleton by the tendons. They are called voluntary because it takes a conscious thought process for them to contract and therefore create movement. Cardiac (Heart muscle) - This is also a form of involuntary muscle. - They ensure that the heart works automatically and constantly. The shape of the muscle is designed to transmit electric message quickly so to keep the heart working in an ordered fashion and react to exercise or rest. Involuntary (Smooth muscle) - It is not possible to consciously control these muscles. - They are essential in maintaining the ‘working body.’ - They are found in the in the walls of your arteries, blood vessels and intestines creating dilation and constriction which forces blood, food etc to move around in your body.

MUSCLE ATTACHMENT A tendon is a very strong, non-elastic cord that joins the muscle to the bone. Here you can see the tendon attaching the bicep and tricep to the humerus. The bone (radius and ulna) is pulled by the tendon when the muscle contracts.

THE ACTIONS OF MUSCLES Muscles are designed to contract, therefore they can only pull and not push. Therefore muscles always work in pairs, so that contractions of one muscle moves the joint in one direction, while contraction of the other muscle moves it in the opposite direction. For example, the contraction of the biceps bends the elbow, while the contraction of the triceps straightens the elbow.

ORIGIN AND INSERTION Look at this diagram again. The terms origin and insertion are used to describe where movement is inititiated from and the point at where the movement will begin. The diagram shows a bending elbow. The origin depicts the end of the muscle that is attached to the fixed bone. Insertion describes the end of the muscle that is attached to the bone that moves.

PRIME MOVERS (AGONISTS) TYPES OF MUSCLE ACTION l PRIME MOVERS (AGONISTS) Agonists are the muscles which work to create motion. It is the muscle that initially contracts to create a movement. ANTAGONISTS These are the opposing muscles to the agonists. They relax to allow a movement to take place. SYNERGISTS Synergistic muscles are those which aid in a movement, but they are not meant to be the main action causing muscle for the desired movement.  Eg. a perfect example of this relationship is the Hamstring group.  The hamstrings are designed to assist with hip extension, but the primary mover for hip extension are the Glutes.

Using this picture again, describe how the man raises his arm Using this picture again, describe how the man raises his arm. Include the terminology that we have just covered. This picture shows a man raising his forearm by bending at the elbow. This occurs due to an agonistic movement (contraction) by the bicep and antagonistic response (relaxation) by the tricep. The point of origin for this movement is at the top of the humerus by the shoulder joint, and the point of insertion is at the base of the humerus at the elbow joint.

What is this skeleton doing? Which is the prime mover involved in raising his leg? Which is the antagonistic muscle during this action? When the other leg rises to take the next step, this leg lowers to the ground, describe this movement in relation to agonist and antagonistic muscles. Where is the point of origin and insertion for this movement?