The Skeletal System and Its Movements 31Closed and Open Kinematic Chain Movements
Begin standing in fifth position with the arms in low fifth, and perform the following movements, dis-
tinguishing between open and closed kinematic chains.- Lower extremity movement. Plié and then bring the left foot up to touch the right knee (retiré).
The right leg is working as a closed kinematic chain. How is the left leg working? How does the con-
cept of open and closed kinematic chains relate to the terminology of the support and gesture leg
used in dance? - Upper extremity movement. Bring the arms overhead, from low to high fifth position. What type
of kinematic chain does the arm movement represent? How could arm movement be changed in dance
to create a condition in which the distal segment is fixed?
CONCEPT DEMONSTRATION 1.4
FIGURE 1.17 Open and closed kinematic chain move-
ments. The foot of the support leg is fixed on the
ground, and the right leg is functioning as a closed kine-
matic chain. In contrast, the left foot and the left hand
are free to move, and hence these limbs are functioning
as open kinematic chains.
Maurya Kerr as a student at Pacific Northwest Ballet School.
Summary
The skeletal system is composed of the bones of the
body, the related cartilages and ligaments, and the
joints that connect these bones together. Bones can
be classified according to their shape as long, short,
flat, and irregular bones. Their shape is in accor-
dance with their functions of providing support,
protection, sites for muscle attachments, and levers
for movement. Although bones have great compres-
sive and tensile strength, they are constantly being
remodeled in accordance with applied stresses and
the availability of calcium and other key nutrients.
A total of 206 bones come together to form the
skeleton. The skeleton can be divided into the axial
skeleton and the appendicular skeleton (upper
extremity and lower extremity), and adjacent bones
within these divisions are connected by fibrous, carti-
laginous, or synovial joints. Synovial joints contain a
joint cavity and primarily give rise to the movements
we associate with the limbs. These synovial joints can
be further classified according to their shape and
the number of axes and planes of movements they
allow. Standardized terminology has been developed
to clearly describe the planes, axes, and associated
movements of joints. In functional movement, joints
serve dual functions of stability and mobility. The
demands of these opposite functions can in part be
met by the change in stability offered by close- and
loose-packed positions. In functional movement,
joints often work in conjunction with other joints,
rather than in isolation. The concepts of open and
closed kinematic chains help describe the potential
linkings of adjacent joints.