Overview of Muscles
| Terms / Vocabulary | |
| Muscle origin | is part of muscle attached to the immovable bone |
| Muscle insertion | is part of a muscle attached to the movable bone |
| Flexion is | decreasing the angle between two bones |
| Dorsiflexion is | raising the top of the foot closer to shin |
| Plantar flexion is | pointing one’s toe |
| Extension is | increasing the angle between two bones |
| Hyperextension is | increasing the angle greater than 180 degrees |
| Abduction is | moving a limb away from the midline |
| Adduction is | moving a limb toward the midline |
| Circumduction is | moving a limb in a circular manner |
| Rotation is | turning a bone along its long axis |
| Supination and pronation | is the result of the pivot joint between the radius and ulna |
| Supination is | when the palm rotates up |
| Pronation is | palm of hands rotating down |
| Inversion is | sole turning inward |
| Eversion is | sole turning outward |
| Elevation is | moving superior |
| Depression is | moving inferior |
| Protraction is | movement in the anterior direction |
| Retraction is | movement in the posterior direction |
Muscle Tissue
Muscles distinct properties include; excitability, contractility, extensibility, and elasticity.
Excitability (irritability) – ability to receive and respond to stimulus. Example neurotransmitter, pH changes, or hormones stimulate a reaction/response.
Contractility – ability to shorten forcibly.
Extensibility – ability to be stretched or extended, they can be stretched beyond their resting length.
Elasticity – ability of muscle fiber to return to its resting length after being stretched
Muscles respond to signals from a motor axon, this property is ________________________
To flex the arm, it requires muscles to shorten or ___________________________________
Bending toward your toes stretches the hamstring muscles, this property is ______________
Three Types of Muscle
Cardiac muscle is found only in the heart. It is striated, involuntary, and contains intercalated discs. Smooth muscle does not have striations, visceral, involuntary, and can maintain slow and sustained contractions. Skeletal muscle is the longest muscle cell types. They have striations, voluntary, contract rapidly, but tire easily.
Functions of skeletal muscle include producing movement, maintaining posture, stabilizing joints, and generating heat.
Structure of skeletal muscles – composed of skeletal muscle, connective tissue, nervous tissue, and blood.
Questions:
Would you consider cardiac and skeletal muscle to have high metabolic activities? ______________
To produce and utilize ATP, would you expect increased amounts of blood flow for nutrients? _______
Do you want your heart muscle to run out of oxygen? _________________________________
Would you expect exercise and training to stimulate increased blood vessel growth in muscle? Why? ________
Does an Olympic 100M sprinter have an extensive muscle mass and blood flow? _____________
Does a sedentary individual have as much skeletal muscle? Why? ______________________
Muscle is covered by a network of connective tissue. Layers of dense connective tissue surrounded separate muscle, called fascia. The fascia extends beyond the muscle eventually forms tendons that fuse on the periosteum of bone.
Aponeuroses – broadsheets of connective tissue
Epimysium connective tissue that surrounds the whole muscle
Perimysium – connective tissue that surrounds individual bundles (fascicles)
Endomysium – connective tissue that covers it individual muscle fibers (muscle cells)
All these connective tissue sheets are continuous with one another as well with the tendons that attach to bones. When a muscle fiber contracts it pulls on the fascial sheaths to transmit the forces to its attachment on bone.
Example
Think of muscle fibers as licorice pull and peels. Each piece of licorice is a muscle bundle that contains several muscle fibers lined up next to each other and surrounded by the perimysium. Each of the individual ropes that we could pull apart are surrounded by a layer of endomysium. We can place several pieces of licorice (muscle bundles) together and surrounded with a packaging sheath called the epimysium.
Can you make another example of layers of wrappings or coverings to explain muscle and its fascia? ________________