Movements


Once we know how to accurately refer to the points within the body in a three dimensional space we need to be able to talk about how they get into these positions, how the joints move to change our shape. Again it is important to remove any ambiguity so we refer to these movements as occurring at joints, not limbs. Shoulder flexion is more precise than arm flexion or even upper arm flexion, it tells us where the movement is happening. Rotation is an exception, often referred to as a limb rotating at a particular joint.

Definitions

  • Flexion is the movement of the limb in the sagittal plane away from the neutral position. Standing with your arm by your side and raising your entire arm directly in front of you is shoulder flexion. With your shoulder still and your elbow bent it would be elbow flxion. Bringing your knee up behind you is knee flexion. Bending your whole body forward is flexion of the spine. I'm sure you can think of a few more, the defining aspect of flexion is that it happens in the sagittal plane, the one that splits the body left/right.
  • Extension is the movement back toward neutral from a flexed position. So bringing the arm back down is extension, straightening the spine again is extension. Hyperextension is the continuation of this movement past the neutral position so if you arch your back it is being hyperextended.
  • Abduction happens in the frontal plane and refers to a movement away from the midline. Keeping your arm straight and taking it out to your side is abduction. Spreading both arms and legs into a star shape is abduction of the shoulder and the hip joints respectively.
  • Adduction (note the 'add') is bringing the limb back in toward the midline. Moving across the midline is also referred to as adduction.
  • Rotation refers to movement around a central axis. The spine rotates around it's own axis when we turn to one side or rotate the neck. The arm rotates around an axis roughly in line with the shaft of the humerus during rotation at the shoulder joint.
  • Medial rotation refers to the rotation of a limb toward the midline. Your right humerus (upper arm) has to medially rotate at the shoulder to bring your hand into your guitar
  • Lateral rotation refers to rotation away from the midline. Your left humerus rotates laterally at the shoulder when you need to fret high up on the neck.

Of course these movements rarely happen in isolation and throughout the program I refer to them in combinations. For example:

To reach your right hand around to your guitar the shoulder has to do a few things. Firstly you can see that it is abducted away from the midline. It is also slightly flexed, in front of the body to reach over the width of the guitar. The elbow is also flexed and the upper arm has had to rotate medially at the shoulder to bring the hand down on to the guitar.