THE SKELETON

THE MUSCLES

The muscles play a major role in supporting the human skeleton and allowing it to move. Muscles hold together the bones and joints of the skeleton. They are the skeleton’s support system. They are placed over the joints of the body to allow them to function. The key point to remember is that muscles don’t push they only pull.

MOVEMENT OF THE JOINTS: FLEXION: The movement at the joint which makes the angle at the joint smaller. In order for the movement to happen at the knee, the hamstring flexes and PULLS the tibia and fibula towards the femur. EXTENSION: The movement at the joint which makes the angle at the joint larger. In order for the movement to happen, the quadriceps flexes and PULLS the tibia and fibula away from the femur.

When you bend at the knee, the hamstrings are the working muscles which are pulling the lower leg towards the upper leg. Therefore, the hamstring is called the AGONIST MUSCLE. At this time, the quadriceps are relaxing, allowing the movement to happen. They are called the ANTAGONIST MUSCLE. Therefore… When you straighten the knee, the quadriceps are the working muscles which are pulling the lower leg away from the upper leg. Therefore, the quadriceps are called the AGONIST MUSCLE. At this time, the hamstrings are relaxing, allowing the movement to happen. They are called the ANTAGONIST MUSCLE. MOVEMENT: KNEE FLEXION AGONIST: HAMSTRING ANTAGONIST: QUADRICEP MOVEMENT: KNEE EXTENSION AGONIST: QUADRICEP ANTAGONIST: HAMSTRING

When we bend our arm, the angle at the joint is getting smaller. Therefore the movement is _______________. The ___________ is pulling the radius and ulna towards the humerus. When we straighten our arm, the angle at the joint is getting bigger. Therefore the movement is _______________. The ____________ is pulling the radius and ulna away from the humerus. EXTENSION OF THE ELBOW: AGONIST: __________ ANTAGONIST MUSCLE: __________ FLEXION OF THE ELBOW: AGONIST: __________ ANTAGONIST MUSCLE: __________ EXTENSION OF THE ELBOW: AGONIST: ______________ ANTAGONIST MUSCLE: ______________ FLEXION OF THE ELBOW: AGONIST: ______________ ANTAGONIST MUSCLE: ______________