72 Dance Anatomy and Kinesiology
T
he spine, or vertebral column, is the central
organizing structure of the skeleton and the
most fundamental element of the axial skeleton.
For this reason it is the first anatomical region dis-
cussed in this text. The vertebral column as a whole
articulates with the head, ribs, and pelvis, whereas
individual vertebrae articulate with each other.
These various articulations allow for movements
of the head, trunk, and pelvis. Due to its central
location, the spine also functions to provide vital
support for upright posture, and to transmit forces
to and from the upper and lower extremities. In
dance, great demands are placed on the spine to
maintain the desired positioning of the torso and
help support another dancer during partnering
as shown in the photo on page 71. In addition to
strength, dance movements such as arabesques or
jazz layouts require exceptional spinal flexibility and
complex neuromuscular coordination to achieve the
desired aesthetics of the movement. With dance, in
contrast to many sports, great attention is also paid to
positioning or alignment of the spine whenever the
limbs are in movement. Hence, better understanding
of both how to move and how to stabilize the spine
can enhance dance skill.
This chapter will present basic anatomy and
mechanics of the spine that influence optimal per-
formance and injury vulnerability. Topics covered
will include the following:- Bones and bony landmarks of the spine
- Joint structure and movements of the vertebral
column - Description and functions of individual muscles
of the spine - Ideal spinal alignment and common deviations
- Spinal mechanics
- Muscular analysis of fundamental spinal move-
ments - Key considerations for the spine in whole body
movement - Special considerations for the spine in dance
- Conditioning exercises for the spine
- Back injuries in dancers
Bones and Bony Landmarks of the Spine
The spine extends from the skull to the tip of the
tailbone (coccyx). It is composed of 33 consecutive
small bones called vertebrae (L. joint) and henceis commonly called the spinal column or vertebral
column. These vertebrae are arranged in five con-
tiguous regions and are numbered consecutively
by region as seen in figure 3.1. Seven vertebrae are
located in the neck region and are called cervical
vertebrae (C1-C7) (L. cervix, neck); 12 are in the
region of the chest or thorax and are called thoracic
vertebrae (T1-T12) (G. thorax, chest); five are in the
low back region and are called lumbar vertebrae
(L1-L5) (L. lumbus, loin); five form the sacrum
(L. sacred bone) at the back of the pelvis; and the
lowest four (three to five) are only partially formed
and make up the coccyx, or tailbone. Since in the
adult the five sacral vertebrae are fused to form the
sacrum and the four coccygeal vertebrae fused to
form the coccyx, only the upper 24 (7 cervical, 12
thoracic, and 5 lumbar) are movable. Although the
number of cervical vertebrae tends to be constant,
numerical variations of thoracic, lumbar, and sacral
vertebrae occur in approximately 5% of otherwise
normal people (Moore and Agur, 1995).
The vertebrae found in each of these regions
differ in both shape and size in accordance with
function. For example, the vertebral column as a
whole is shaped like an extended pyramid such that
the vertebrae get progressively larger from cervical
to lumbar regions. This arrangement has functional
significance since each vertebra must bear the weight
of all the body parts above it, until the spine rests on
the sacrum, where the weight of the body is trans-
ferred. Since the weight of the body is transferred
to the pelvic girdle via the sacrum, the bones of the
coccyx do not have to support the weight of the
upper body and are much smaller.
Although there is variance in structure by region, a
typical vertebra consists of a vertebral body, vertebral
arch, and seven processes as shown in figure 3.2A.
The vertebral body is the large, cylindrical anterior
portion of the vertebra, through which most of the
weight of the body is transmitted. Extending posteri-
orly from the body is a hollow partial ring termed the
neural arch or vertebral arch, formed by two pedicles
and two laminae. The pedicles (L. pes, foot) are short,
broad processes that extend back from the body of
the vertebra to attach to the broad, flat plates of bone
called laminae (L. a thin plate). This vertebral arch
and the posterior surface of the body of the vertebra
form the walls of the very important opening, the
vertebral foramen (L. an aperture). The vertebral
foramen from successive vertebrae of the vertebral
column form the vertebral canal or spinal canal,
which houses and provides protection for the spinal
cord and its related membranes, vessels, and nerve
roots. Small indentations located on the upper (supe-