At the conclusion of this chapter, the student should be able
- 1. Name, locate, and describe the structures and ligamentous
reinforcements of the articulations of the spinal column and thorax.
- 2. Name and demonstrate the movements possible in joints of
the spinal column and thorax, regardless of starting position.
- 3. Name and locate the muscles and muscle groups of the spinal
column and thorax and name their primary actions as agonists, stabilizers,
neutralizers, or antagonists.
- 4. Analyze the fundamental movements of the spinal column
and thorax with respect to joint and muscle actions.
- 5. Describe the common injuries of the spinal column and thorax.
- 6. Perform an anatomical analysis of the movements of the
spinal column in a motor skill.
If you were faced with the problem of devising a single mechanism
that would simultaneously (1) give stability to a collapsible cylinder,
(2) permit movement in all directions and yet always return to the
fundamental starting position, (3) support three structures of considerable
weight (a globe, a yoke, and a cage), (4) provide attachment for
numerous flexible bands and elastic cords, (5) transmit a gradually
increasing weight to a rigid basinlike foundation, (6) act as a
shock absorber for cushioning jolts and jars, and (7) encase and
protect a cord of extreme delicacy, you would be staggered by the
immensity of the task. Yet the spinal column fulfills all these
requirements with amazing efficiency. It is at the same time an
organ of stability and mobility, of support and protection, and
of resistance and adaptation. It is an instrument of great precision,
yet of robust structure. Its architecture and the manner in which
it performs its many functions are worthy of careful study. From
the kinesiological point of view, we are interested in the spine
chiefly as a mechanism for maintaining erect posture and for permitting
movement of the head, neck, and trunk.
To understand these functions of the spine, it is necessary to
have a clear picture, first, of the spinal column as a whole and,
second, of the distinguishing characteristics of the different regions. The
spinal column, consisting of seven cervical, twelve thoracic, and
five lumbar vertebrae, the sacrum (five fused sacral vertebrae),
and the coccyx (three to five fused vertebrae), presents four curves
as seen from the side (Figure 9.1). At birth, the vertebral column
is convex backward. The thoracic and sacrococcygeal curves remain
convex to the rear and are considered primary curves. The cervical
and lumbar curves reverse direction of the curvature during infancy
and early childhood and are referred to as secondary curves. The
curvature at the cervical region develops when the infant raises
its head; the lumbar region develops its anterior convexity when
the infant assumes an upright posture and begins to walk. The curves
are a response to gravity and continue to develop through puberty.