Skeletal Muscle is one of the 3 main muscle structures of the human body.

Skeletal muscle is referred to as a “striated muscle”. It is voluntarily controlled. This means that we choose to move these muscles.

This group of muscles attach to bones and allows for movement by applying force to the Skeletal System.

The control is done through nerve stimulation from the nervous system. The muscle itself is wrapped in a connective tissue. Skeletal muscles are cylindrical in shape.

These muscles have fibers with many nuclei called multinucleated. Each cell has several thread-like fibers called myofibrils. The smallest aspect of a skeletal muscle is called a sarcomere. Within the sacromere is a myosin and actin protein filament.

The term muscle refers to a few to several “bundles of muscle fibers” held together by connective tissue.

Each muscle has two sides and are classified as:

1.)  Origin – is one end that attaches to a bone closer to the center of the body.

2.)  Insertion – is the other end that attaches to a joint that connects to a second bone.

The Following is the action process of the Skeletal muscle.

Skeletal muscles are stimulated by acetylcholine which is released

1.)  This causes a chain event that “Excites” the cells.
2.)  Calcium ion is released which attaches to myofibrils to allow for muscular contraction.
4.)  Calcium affects the actin by binding to tropomysoin
3.)  ATP (Adenosine triphosphate) is required for muscular contraction

Different types of Skeletal muscles

–   Type I  –  slow twitch  –  Marathon runners have more of these

–   Type II –  fast twitch  –  Sprinters and Weightlifters have more of these

*Type II are again divided into IIa, IIx, and IIb

Humans only have I, IIa, and IIx
– other variations are found in other mammals

Others types of muscle are as follows

Cardiac Muscle
Smooth Muscle