Ch. 7.5 Muscular System Key Terms
abduction
moving a body part away from the midline.
dorsiflexion
bending backward or bending the foot toward the knee.
fascia
a tough, sheetlike membrane that covers and protects the tissue. It is one way muscles attach to bones.
muscular system
the system made up of more than 600 muscles, which are bundles of muscle fibers held together by connective tissue.
skeletal muscle
muscle that is attached to bones and causes body movement. It is voluntary.
cardiac muscle
forms the walls of the heart and contracts to circulate blood. It is an involuntary muscle.
elasticity
allows the muscle to return to its original shape after it has contracted or stretched.
flexion
decreasing the angle between two bones, or bending a body part.
origin
when a muscle attaches to a bone, it is the end that does not move.
supination
turning a body part upward.
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.
excitability
also called irritability; the ability to respond to a stimulus such as a nerve impulse
insertion
the end of the muscle that moves when the muscle contracts.
plantar flexion
bending forward or bending the foot away from the knee.
tendons
strong, tough, fibrous connective-tissue cords. They are one way muscles attach to bones.
contractibility
the property of muscle fibers that are stimulated by nerves to contract, or become short and thick, which causes movement.
extensibility
the ability to be stretched.
involuntary
functioning without conscious thought or control. Cardiac and visceral muscles are examples.
pronation
turning a body part downward.
visceral muscle
also called smooth muscle; found in the internal organs of the body (like the digestive system) and contracts to cause movement in these organs. It is an involuntary muscle.
contracture
a severe tightening of a flexor muscle resulting in bending of a joint.
extension
increasing the angle between two bones, or straightening a body part.
muscle tone
the state of partial contraction in which muscles are partially contracted at all times, even when not in use; described as a state of readiness to act.
rotation
turning a body part around its own axis, like turning the head from side to side.
voluntary
meaning a person has control over its action. Skeletal muscle is an example.