Antagonistic Pairs
Skeletal muscles are attached to the skeleton, and their contraction causes the movement of bones
at a joint. Because muscles shorten when they contract, they can only pull; they cannot push.
Therefore, muscles work in antagonistic pairs. Usually, contraction of one member of the pair
causes a bone to move in one direction, and contraction of the other member of the pair causes the
same bone to move in an opposite direction.
Flexion
Extension
Adduction
Abduction
Rotation
Inversion
Eversion
Moving jointed body parts toward each other
Moving jointed body parts away from each other
Moving a part toward a vertical plane running through the longitudinal rnidline of
the body
Moving a part away from a vertical plane running through the longitudinal midline
,,
of the body
Moving a body part around its own axis; circumduction is moving a body part in
a wide circle
A movement of the foot in which the sole is turned inward
A movement of the foot in which the sole is turned outward
Observation: Antagonistic Pairs
For each of the following muscle pairs, state their opposing action's by inserting one of the�e
functions: flexes, extends, raises, lowers, adducts, or abducts.
1. The biceps brachii ____________________________________ the elbow.
The triceps brachii ________________________________ the elbow.
2. The sternocleidomastoid _________________ the neck.
The trapezius __________________________ the neck.
3. The sartorius _________________________ the thigh.
The adductor longus _________________________ the thigh.
4. The iliopsoas __________________________ the hip.
The .gluteus maximus ___________________________ the hip.
5. The quadriceps femoris group _________________ the knee.
The hamstring group ________________________________ the knee.