1. Anatomical reference position- erect standing position with all body parts, including the palms or hands, facing forward; considered the starting position for body segment movements.
2. Angle of projection- the direction at which a body is projected with respect to the horizontal.
3. Anterior- toward the front of the body.
4. Axis of rotation- imaginary line perpendicular to the plane of rotation and passing through the center of rotation.
5.
Balance- ability to control equilibrium
6. Center of gravity- point around which a body's weight is equally balanced, no matter how the body is positioned.
7. Curvilinear- along a curved line.
8. Extension- the movement that returns a body segment to anatomical position for a position of flexion.
9. External rotation- rotation is away from the midline of the body
10. Flexion- includes anteriorly directed sagittal plane rotations of the head, trunk, upper arm, forearm, hand, and hip, and posteriorly directed sagittal plane rotation of the lower leg.
11. Force- push or pull; the product of mass and acceleration
12. General motion- motion involving translation and rotation simultaneously.
13. Hamstrings- the biceps femoris, semimembranosus, and semitendinosus.
14. Hyperextension- the rotation beyond anatomical position in the direction opposite the direction of flexion.
15. Impact- collision characterized by the exchange of a large force during a small time interval
16. Mediolateral axis- imaginary line around which sagittal plane rotations occur.
17. Posterior- toward the back of the body.
18. Plantar flexion- motion bringing the top of the foot farther from the lower leg.
19. Quadriceps- the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.
20. Range of motion- angle through which a joint moves from anatomical position to the extreme limit of segment motion in a particular direction.
21. Rectilinear- along a straight line.
22. Sagittal plane- plane in which forward and backward movements of the body and body segments occur.
23. Stability- resistance to disruption in equilibrium.
24. Stabilizer- role played by a muscle acting to stabilize a body part against some other force.
25. Trajectory- the flight path of a projectile