Parts of a typical skeletal muscle

A typical skeletal muscle consists of two ends and two parts.

Parts of Skeletal Muscle

Ends

A typical skeletal muscle consists of two ends. These are;

1. Origin is one end of the muscle which remains fixed during its contraction.
2. Insertion is the other end which moves during its contraction. In the limb muscles, the origin is usually proximal to insertion.

However, it should be kept in mind that the terms, origin and insertion, are at times interchangeable (e.g. climbing action of latissimus dorsi), and at other times difficult to define, as in the intercostal muscles. They are commonly used for muscles which have clear distinction between the two ends.

Parts

A typical skeletal muscle consists of two parts. These are;

1. Fleshy part is contractile, and is called the ‘belly’.
2. Fibrous part is non-contractile and inelastic. When cord-like or rope-like, it is called tendon; when flattened, it is called aponeurosis.

The fleshy part of the muscle, the belly, is red in color while the fibrous part is white in color. The difference in color makes it easy to differentiate the active contractile area of the muscle from the non-contractile part.