How is Muscle Structured?
In order to understand how muscles are injured it is helpful to know how the muscle is made up. The muscle is surrounded by an outer sheath or covering. Inside this outer sheath are bundles of muscle fibres which are known as fasicles and are themselves surrounded by another inner sheath. If you looked at the bundles very closely you would just be able to see the individual muscle fibres. (The muscle fibres are made up of even smaller parts but a microscope is required to see them). A muscle contracts when two of these microscopic parts link together and slide together (causing the muscle to shorten) or slide apart (causing the muscle to lengthen). If the muscle shortens, the result is movement of a joint in one direction; if it lengthens, it causes movement of a joint in the other direction. The co-ordination of this muscle activity by the brain allows us to perform complex movements such as kicking a football or running.
