The Muscular System

Important Terms for Muscle Movement

Origin• point of attachment to the more stationary bone

Insertion• point of attachment to the more movable bone

Nerve innervation• what nerve “talks” to the muscles to cause contraction or relaxation

Action• coordinated response of a group of muscles to bring body into movement

TREND:• When a muscle contracts, it shortens. This shortening causes the muscle’s insertion to move toward the origin… movement

Muscles for Practice

Biceps brachii• Origin

• Insertion

• Nerve Innervation

• Action

Use 3 references to complete the chart:Wingerd pgs. 213, 223BRB pg. 366Musculoskeletal Anatomy pgs. 5, 7, 25, 75

Production of MovementOrigin Innervation Insertion Action

Prime mover (agonist) • muscle that causes a desired action

Antagonist• muscle that relaxes & yields to the prime mover

Synergist• muscle that works with prime mover… steadying the movement by stabilizing the joint & moving bones

Fixator• muscle that stabilizes the bone & joint at the muscle’s origin

Types of Muscle Contraction

Isotonic contraction– Produces movement as the muscle pulls on

the bone– Consistent load through a range of motion– 2 types

• Concentric (+) – Muscle shortens & pulls on bone to produce

movement– Decreases joint angle

• Eccentric (-)– Muscle length increases during contraction to

produce movement

Isometric contraction– Produces muscle tension but muscle does

not shorten– Same length