218
UNIT TWO
rated by masses of F brocartilage called
intervertebral discs
and
connected to one another by ligaments. The vertebral column
supports the head and the trunk of the body, yet is fl exible
enough to permit movements, such as bending forward, back-
ward, or to the side and turning or rotating on the central axis.
It also protects the spinal cord, which passes through a
verte-
bral canal
formed by openings in the vertebrae.
An infant has thirty-three separate bones in the verte-
bral column. ±ive of these bones eventually fuse to form
the sacrum, and four others join to become the coccyx. As a
result, an adult vertebral column has twenty-six bones.
Normally, the vertebral column has four curvatures,
which give it a degree of resiliency. The names of the curves
PRACTICE
18
Locate and name each of the bones of the cranium.
19
Locate and name each of the facial bones.
20
Explain how an adult skull diF
ers from that of an infant.
7.7
VERTEBRAL COLUMN
The
vertebral column
extends from the skull to the pelvis and
forms the vertical axis of the skeleton
(f g. 7.32)
. It is com-
posed of many bony parts called
vertebrae
(ver
te
˘-bre) sepa-
(a)
(b)
Parietal bone
Posterior fontanel
Anterior fontanel
Mastoid fontanel
(posterolateral
fontanel)
Sphenoidal fontanel
(anterolateral fontanel)
Sphenoid bone
Anterior fontanel
Posterior fontanel
Occipital bone
Frontal bone
Nasal bone
Zygomatic bone
Frontal suture
(metopic suture)
Coronal suture
Frontal bone
Sagittal suture
Temporal bone
Mandible
Maxilla
FIGURE 7.31
±²ontanels.±(
a
) Right lateral view and (
b
) superior view of the infantile skull.
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