Key Terms Ch. 7:5 Muscular System

voluntary

a person has control over its action

fascia

a tough, sheetlike membrane that covers and protects the tissue

elasticity

allows the muscle to return to its original shape after it has contracted or stretched

skeletal muscle

attached to bones and causes body movement

contract

become short and thick

flexion

decreasing the angle between two bones, or bending a body part

cardiac muscle

forms the walls of the heart and contracts to circulate blood

visceral (smooth) muscle

found in the internal organs of the body, such as those of the digestive and respiratory systems, and the blood vessels and eyes

involuntary

function without conscious thought or control

extension

increasing the angle between two bones, or straightening a body part

excitability

irritability, the ability to respond to a stimulus such as a nerve impulse

muscular system

made up of more than 600 muscles

abduction

moving a body part away from the midline

adduction

moving a body part toward the midline

circumduction

moving in a circle at a joint

contractibility

muscle fibers that are stimulated by nerves contract, or become short and thick, which causes movement

contracture

severe tightening of a flexor muscle resulting in bending of a joint

muscle tone

state of partial contraction

tendons

strong,tough, fibrous connective-tissue cords

extensibility

the ability to be stretched

insertion

the end that moves when a muscle contracts

rotation

turning a body part around its own axis; for example, turning the head from side to side

origin

when a muscle attaches to a bone, the end that does not move