Myology, Muscles of the Head, Neck, and Upper Limb (Lab 5)

What is a muscle and what is it composed of?

A muscle is an organ. It is comprised of skeletal muscle tissues, nervous tissues, blood vessels, and connective tissues.

Describe the organization of a muscle

Each muscle contains multiple fascicles. Each fascicle contains multiple skeletal muscle fibers.

What is the belly of the muscle?

The part of the muscle that contains the muscle fibers and fascicles

What is the tendon of the muscle?

The visible connective tissue on the ends of the muscle

What is the epimysium?

The outermost layer of connective tissue on a muscle

What are the different arrangements of fascicles?

Parallel, convergent, pennate, and circular.

Describe a parallel fascicle arrangement

A parallel fascicle arrangement in a skeletal muscle is the simplest possible arrangement. The force of contraction works to shorten the muscle, bringing its two attachments closer together.

Describe a convergent fascicle arrangement

A convergent fascicle arrangement has a narrow attachment on one side and a broad attachment on the other side. All parts of the muscle may work together or be activated independently with independent actions.

Describe a pennate fascicle arrangement

Pennate = feather. A pennate arrangement of fascicles involves their attachment at an angle to the tendon. Unlike parallel arrangements of fascicles in similarly sized muscles, pennate muscles have many more cells but much shorter muscle cells and fascicles. The greater number of cells results in a stronger muscle that has a shorter range of action.

What are the two attachments of a muscle?

The origin and insertion

Describe the origin

The origin is the more stable attachment that is often proximally or more medially located on the body.

Describe the insertion

The insertion is the more mobile and often more distally located attachment.

What are synergists

Synergists (agonists) work in generally the same way, although they might have slight differences in their attachments.

What are antagonists

Antagonists are muscles that work opposite one another.