BONES AND MUSCLES



The human body has over 500 muscle responsible for all types of movement. Each of these muscles has a name; for example, the biceps brachii and now the triceps brachii, responsible for both forearm flexion and forearm extension, respectively. When movement of a body parts occurs, muscles work in a groups rather than individually. Working together enhances a particular movement. During that particular movement, individual muscles will play different roles depending on thier origin and insertion. These different roles can be described as agonists (or prime movers), antagonist, or synergists.

Roles of Muscles and Bones in movement

The muscles in the body provide the means of all movements. When stimulated by a nerve, the muscles contracts to become shorter and thicker and thus it pulls the bone at the movable end. Most actions in our body like standing, walking, running, playing ect. require combined action of several muscles. Movements of different parts of the body are usually made easier due to leverages actions in the skeleton. Functioning of all the three types of levers can be observed in the human skeleton



1. LEVERS OF FIRST ORDER

In these, the function is in the center with weight and power on either side. For example, the joint between the first vertebra (atlas) and occipital bone of skull exhibits first class lever, in which the joint is the fulcrum, contraction of back muscles in the effort and facial part of the skull on raised head acts as the weight of resistance.

2. LEVERS OF THE SECOND ORDER

In these, the weight is in hte middle between the pòwer and the fulcrum. For example human body resting on toes. Here the toe forms the fulcrum and contracting calf muscle provides effort.

3. LEVERS OF THE THIRD ORDER

Here the power is in the middle and the weight and fulcrum on their side. For example the flexing of the flexing of the elbow of forearm. Here the elbow joint acts as fulcrum, and the distal part of hand provide resistance.
The  contracting biceps muscles exert the effort in between fulcrum and resistance.