What Causes The Muscle Contraction

The nervous system is always in control of all activities during movement. When a neurotransmitter or message is sent for movement to occur, your body releases energy, in the form of adenosine triphosphate (A.T.P.). A.T.P causes the contraction or shortening of skeletal muscle. Muscles contract and shorten and as a result of this they are responsible for the movement of the body. In order to have movement the body needs ligaments, tendons muscles, joints, bones and the neurotransmitter or message sent for movement.

Skeletal muscles that produce movement occurs at any given joint, only one of the articulating bones will move. The point of articulation, or where the muscles and the bones connect, is known as a joint.
Bones are connected
Tendons are fibrous connective tissue which attaches muscle to bone. A tendon serves to move the bone or structure.

Muscles work in pairs, one muscle contracts and pulls on the bones to which they are attached and cause the bone to move. Each pair contains an agonist (the contracting muscle) and an antagonist (the opposing, relaxing muscle). When we have to work, a muscle receives an electrical signal from the brain, causes a movement to occur, because this causes the contraction in it. The agonist and the antagonist must contract and relax equally to ensure a smooth movement.

An example of this would be in the arm, the humerous bone is connected to the hinge joint by ligaments, then onto the radius and the ulna bones of the forearm. The biceps muscle to the anterior of upper arm flexes the elbow, whereas the triceps is posterior of the upper arm and extends the elbow. Both these muscles are connected by tendons to the bones. Muscles only pull, they never push, the biceps contract to pull the forearm and the triceps contracts to pull straighten the forearm. This is why muscles work in pairs and cannot work without skeletal system, joints, muscle, ligaments or tendons in order to create