Muscle Movement/Contraction Vocab

Flashcards on Skeletal Muscle Structure and Function

Concentric Contraction

Contraction with shortening where a muscle produces an active force and simultaneously shortens.

Eccentric Contraction

Contraction with elongation; muscle produces an active force but is simultaneously pulled to a longer length by a dominant external force.

Isometric Contraction

Contraction with no movement; muscle generates an active force while remaining at a constant length.

Agonist

Muscle or muscle group most directly related to performing a specific movement.

Antagonist

Muscle or muscle group that oppose the action(s) of the agonist.

Co-contraction

Occurs when agonist and antagonist muscles are simultaneously activated to stabilize and protect a joint.

Synergists

Muscles that work together to perform a particular action.

Force-Couple

When muscles produce force in different linear directions but produce the same rotary direction.

Length-Tension Relationship

The length of a muscle has a significant impact on the force it can produce.

Horizontal plane movement of the knee

Internal and external rotation

Function of Anterior Cruciate Ligament

Resists anterior translation of the tibia (open-chain) and posterior translation of the femur (closed-chain).

Knee Extensors (Quadriceps)

Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

Hamstrings (Knee Flexors)

Semitendinosus, semimembranosus, biceps femoris (long head), and biceps femoris (short head).

Actions of Popliteus

Knee internal rotation and knee flexion

Patellofemoral joint functions

Acts to transmit quadriceps force across the knee and enhances the leverage of the quadriceps.