Types of Skeletal Muscles according to Fiber Patterns 1:
Skeletal muscles are categorized according to the manner in which the muscle fibers are oriented to the tendons of attachment.
In some muscles, the fibers are quite long and parallel and extend the length of the muscle (from attachment to attachment). This type of skeletal muscle is referred to as a ribbon or strap muscle.
In other muscles, the striated muscle fibers are oriented obliquely between the two tendons of attachments. Such muscles are said to have a quadrilateral structure.
If the striated muscle fibers appear to be attached to one tendon in a featherlike arrangement, the muscle structure is known as pennate. If all of the fibers are on one side of the tendon, the muscle structure is unipennate.
If the fibers are on two sides, the muscle structure is bipennate. If the feather-like arrangement is branched, the muscle structure is multipennate.
The strength of a skeletal muscle is proportional to the cross-sectional area of its fibers. Therefore, a multipennate muscle is generally much stronger than a ribbon muscle.
Distance of Contraction.
On the other hand, the longer the fibers of a muscle, the greater will be its distance of contraction. As a very loose rule of thumb, a skeletal muscle can contract to three-fifths of its resting length. The ribbon muscles have long distances of contraction.