Planes and axes of motion

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Human motion is complex. We confront this complexity by analyzing movement in a definite sequence:

1. We name the joints at which movement occurs
2. We describe the motion at ONE JOINT AT A TIME.
3. At each joint, we describe the motion in ONE PLANE AT A TIME

Depending on the joint, we must analyze the motion at just ONE, or TWO, but never more than THREE PLANES.

1. Sagittal
2. Frontal (sometimes called the coronal plane)
3. Transverse (sometimes called the horizontal plane)

Your text illustrates the three planes on a body in anatomic position on page 3. Disregard their use of x, y, and z orientations.

Another view of the cardinal planes

When we describe motion, we mentally move the plane so that it "cuts through" the joint at or near the joint surface. Imagining a plane which cuts through at the level of a joint permits us to draw a two-dimensional (or planar picture of the joint:

• sagittal plane view of the knee joint
• frontal plane view of the hip joint
• transverse plane view of the hip joint

Each plane is oriented in relation to the body, not to the "world." In other words, when the body or any of its segments change position, the planes change their orientation along with them. EACH PLANE IS DEFINED BY AN AXIS

Each plane is defined by an axis, a line that is perpendicular to the plane. When we observe a drawing of the joint in a single plane, we appreciate the joint's axis as a point; in the drawings linked above, an 'x' marks the joint axis.

Reference:

Smith, L.K., Weiss, E.L. & Lehmkuhl, L.D. (1996). Brunnstrom's clinical kinesiology (5th ed.). Philadelphia: F.A. Davis.

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Last updated 7-3-00 © Dave Thompson PT