2-17. FUNCTIONS OF THE VERTEBRAL COLUMN
The vertebral column functions as a strong pillar for the support of the trunk and
the cranium, provides articular surfaces for the attachment of the ribs, and affords
protection for the spinal cord and the roots of the spinal nerves. It transmits the weight
of the trunk to the inferior extremities. Although forming a continuous support-bearing
column, it is flexible enough to permit bending of the trunk in various directions. The
vertebral canal, which follows the different curves of the column, accommodates and
protects the spinal cord; it is formed by the superimposition of the vertebrae in each of
which there is a vertebral foramen. Despite its flexibility, the vertebral column is
sufficiently firm and strong to serve as a base for the origin of many ligaments and
muscles and as a lever for the spinal muscles, which function to maintain the upright
position of the trunk.
2-18. VERTEBRAL STRUCTURE
a. General. Most of the vertebrae have a similar general structure, that is, they
all present certain characteristics. Thus, certain ones can be used as a pattern and are
called typical vertebrae. In spite of this general similarity, the vertebrae in the different
regions are so modified and present characteristics so peculiar to the region which they
occupy that, when examined separately, it is possible to determine the region to which
b. Typical Vertebrae. Except for slight modifications due to position and
function, all of the typical vertebrae (figure 2-19) have the same general structure. They
are indicated as follows: C-3 to C-7, T-1 to T-12, and L-1 to L-5. A typical vertebra is
A centrum, or body, which is the disk-like central portion.
(2) The neural arch, which is made up of two roots or pedicles (small feet)
and two laminae (layers of bone).
(3) The vertebral foramen, an opening behind the body that is bounded
laterally and posteriorly by the neural arch and anteriorly by the body. The apposition of
all the vertebrae forms the vertebral canal that accommodates the spinal cord.
(4) The vertebral notches, one on the superior border of each pedicle and
one on the inferior border which, by the apposition of the adjacent vertebrae, form the
intervertebral foramina (singular, foramen) for the transmission of the spinal nerves and