Muscular System By: Emily Brosten Stephanie Elhard JAMES VALLEY VOCATIONAL TECHNICAL CENTER

Introduction muscles in the body 2. Muscles are ~ made of bundles of muscle fibers which are held together by connective tissue.

3. When muscle fibers are stimulated by nerves ~they contract or become short and thick.

Voluntary ~ you can willfully control muscles *facial expressions, chewing, swallowing, and movement of the head

Involuntary ~ function without the person thinking about contracting the muscles. *digestive system, heart muscles, and blood vessels ** Some muscles are both voluntary and involuntary ~ example eye blinking

THREE TYPES OF MUSCLES

1. Cardiac muscles ~ cells are packed so closely together its hard to tell one cell from another. ~forms walls of the heart ~contact to circulate blood ~involuntary

2. Visceral/Smooth muscles ~found in internal organs of the body *digestive, respiratory system, blood vessels, and eyes. ~muscles contract to cause movement in these areas ~involuntary function without the person thinking about contracting the muscle

3. Skeletal~ most abundant muscle ~attached to bone ~causes body to move ~voluntary

FUNCTIONS OF SKELETAL MUSCLES

1. Attaches to bones to provide voluntary movement. 2. During contractions provide heat and energy.

3. Helps maintain posture. 4. Some protect internal organs.

SKELETAL MUSCLES ATTACH TO BONES IN VARIOUS WAYS

1.Tendon ~ strong, tough connective tissue cord, connect muscle to bone *Achilles Tendon (attaches to calf muscle and heel bone) *lumbodorsal fascia (surrounds the deep muscles of the back and trunk)

2. Fascia ~ tough, sheet-like membrane that covers and protects tissue *lumbodorsal fascia (surrounds the deep muscles of the back and trunk)

3.Origin ~ When a muscle attaches to the bone, the end doesn’t move. -usually attaches closer to the trunk of the body -where the muscle begins

4. Insertion ~ the end of the muscle that attaches to a bone that moves- where the muscle ends

CHARACTERISTICS OF MUSCLE TISSUES

1. Contractability ~ ability to shorten and thicken (when muscles work they contract that is they get shorter and thicker)

2. Extensibility ~ ability to stretch (when muscle is relaxed it becomes longer and thinner) *some muscles work while others relax *

3.Elasticity ~ ability to return to original length 4. Irritability ~ability to respond to stimulus 5. Tone ~ slight tension in the muscles at all times, even at rest

MOVEMENT PERFORMED BY MUSCLES

1. Adduction ~ moving a body part toward the midline 2. Abduction ~ moving a body part away from the midline

3.Flexion (Flexor) ~ decreasing the angle between two bones and body part

4. Extension ( Extensor) ~ increasing the angle between two bones and body part

5. Rotation ~a circular motion which turns a body part on its axis

6. Sphincters: ring like muscles that close body openings –example: rectum

7. Levators: lift a part of the body

8. Depressors: lower a part of the body 9. Supination: the act of rotating the arm so the palm of the hand is upward.

10. Pronation: the act of rotating the arm so the palm of the hand is turned downward.

Terminology Muscle tone: muscles that are partially contracted at all times, even when they may not be in use.

Contracture: severe tightening of a flexor muscle that results in bending of a joint. Myology: my/o = muscles » ology = study of – the study of muscles

MYOLOGY The Study of Muscles CHARTS