The Muscular System:The Muscular System:

StructureStructure

Muscle tissue is made of special cells that contract.

Muscle tissue is made of special cells that contract.

This action is called a contraction.

Muscle tissue is made of special cells that contract.

This action is called a contraction.

When a muscle contracts, it gets shorter and wider.

A single cell of skeletal muscle tissue is called a muscle fiber.

These cells or fibers are very fine. (1/25,000”)

They can be up to 10” long.

Within skeletal muscles, the fibers are bundled into groups called fascicles.

Fasicles contain muscle fibers and the connective tissue that joins them, called endomysium.(endo- = “inside of”)

Fasicles are bundled into larger groups held together with a connective tissue called perimysium.(peri- = “around”)

Blood vessels and nerves are in the perimysium.

Finally, the entire big bundle (a muscle), is covered in a layer of connective tissue called the epimysium.(epi- = “on the surface”)

This is the surface of the muscle, which can appear silvery.

The endomysium, perimysium, and epimysium are made primarily of collagen.

The endomysium, perimysium, and epimysium are made primarily of collagen.

Collagen is the same protein that gives structure to your skin in the dermis and gives your bones resilience.

At each end of the muscle, all of the connective tissues come together to form a tendon, or sometimes a broad, flat sheet of collagen called an aponeurosis.

At each end of the muscle, all of the connective tissues come together to form a tendon, or sometimes a broad, flat sheet of collagen called an aponeurosis.

Tendons and aponeuroses (plural) are how muscles attach to the skeletal system.

Tendons at the end of each muscle attach the muscle to bone.

Where there is no available bone, or where the muscle force needs to be distributed across a larger area, muscles may attach to an aponeurosis. Some of the abdominal muscles do this.

The End.