Movement of a Human Body in Three-Dimensional Space
Planes of the Body
Sagittal Plane – The plane running vertically, dividing the body into equal right and left halves
Coronal Plane – The plane running vertically that is perpendicular to the Sagittal Plane,
dividing the body into front and back
Transverse Plane – The plane running horizontally through the waist of the body dividing it
into upper and lower regions
Figure 1: Planes of the Body
Joint Movement
Flexion: Planar joint movement where the joint angle
decreases. Joint angle is defined as the angle formed about
a joint in the body by the two connecting limbs. In the
legs, this movement usually occurs along the sagittal
plane.
Extension: Planar joint movement that increases the joint
angle (Figure 2) and acts as the countermovement to
flexion.
Figure 2: Flexion & Extension
Flexion and extension allow for improved stability and
maneuvering rough terrains by stepping over objects. It
also allows for the standing motion.
Abduction: Movement away from the center of the body
(Figure 3). In the legs, this motion typically takes place
along the coronal plane.
Adduction: Movement toward the center of the body
(Figure 3). This is the countermovement to abduction that
brings the legs together.
Abduction/adduction and flexion/extension are not
mutually exclusive, and together they allow a body to walk
with maximum stability.
Figure 3: Abduction & Adduction
Medial Rotation: Rotation toward the sagittal plane
(Figure 4) of the body. This movement rotates a limb
inward. .
Lateral Rotation: Rotation away from the sagittal plane
(Figure 4) of the body. This movement rotates a limb
outward.
Medial and lateral rotation allows a body to pivot and
change direction.
Figure 4: Medial & Lateral
Rotation
Joints of the Leg
Hip Joint: As seen in figure 5, the hip joint is a ball in a socket which gives it the unique ability
to create a wide range of motion. The hip is capable of flexion/extension, abduction/adduction,
and medial/lateral rotation movements. The flexion/extension movement of the hip creates
forward and backward movement of the leg. The abduction and adduction motion is utilized to
maintain the stability of the body, keeping it from tipping over. The rotational ability of the hip
joint allows a person to change direction and adjust body position.
Knee Joint: Figure 6 shows the hinge joint of the human knee. This joint acts similarly to a door
hinge, allowing the knee to flex and extend. The knee joint’s range of motion is helpful when
lifting heavy objects and creating forward movement. The knee is only capable of extension and
flexion.
Ankle Joint: Figure 7 displays the unique structure of a gliding joint. Gliding joints consist of
many small bones allowing the joint to move in a seemingly smooth gliding motion. Although it
is not a ball and socket joint, it is capable of the same range of motion. The ankle’s extension and
flexion is used to lift the body for stability. The ankle’s ability to abduct and adduct helps
maintain balance on uneven walking surfaces.
Figure 5: Hip Joint
Figure 6: Knee Joint
Figure 7: Ankle
Joint