| A | B |
|---|
| adduction | moving a body part toward the midline |
| abduction | moving a body part away from the midline |
| flexion | decreasing the angle between two bones, or bending a body part |
| extension | increasing the angle between two bones, or straightening a body part |
| rotation | turning a body part around its own axis |
| circumduction | moving in a circle at a joint, or moving one end of a body part in a circle while the other end remains stationary for example swinging arm in a circle |
| excitability | irritability, the ability to respond to a stimulus such as a nerve impulse |
| contractibility | muscle fibers that are stimulated by nerves contract, or become short and thick, which causes movement |
| extensibility | the ability to be stretched |
| elasticity | allows the muscle to return to its original shape after it has contracted or stretched |
| muscles | bundles of muscle fibers held together by connective tissue |
| cardiac muscles | forms the walls of the heart and contracts to circulate blood |
| visceral (smooth) muscles | found in internal organs of the body such as the digestive and respiratory systems and the blood vessels and eyes |
| involuntary | without conscious thought or control |
| voluntary | control over actions |
| skeletal muscle | attached to bones and causes body movement |
| tendons | connects muscles to bones |
| fascia | tough, sheet-like membrane that covers and protects the tissue |
| origin | end or area of a muscle that remains stationary when the muscle contracts |
| insertion | end or area of a muscle that moves when the muscle contracts |
| muscle tone | state of partial muscle contraction providing a state of readiness to act |
| contracture | a severe tightening of a flexor muscle, resulting in bending of a joint |
| atrophy | shrink in muscle size or lose strength |
