Anatomy of the Newborn Skull
Although the skull appears to be one large bone,
there are actually several major bones that are connected
together. The major bones that compose the skull of
a newborn include the following:
- 2 frontal bones
- 2 parietal bones
- 1 occipital bone
These bony plates cover the brain and are held together
by fibrous material called sutures.
What are sutures?
Some sutures extend to the forehead, while others
extend to the sides and back of the skull. One suture
in the middle of the skull extends from the front
of the head to the back. The major sutures of the
skull include the following:
- metopic suture - extends from the top of
the head down the middle of the forehead, toward
the nose. The two frontal bone plates meet at the
metopic suture.
- coronal suture - extends from ear to ear.
Each frontal bone plate meets with a parietal bone
plate at the coronal suture.
- sagittal suture - extends from the front
of the head to the back, down the middle of the
top of the head. The two parietal bone plates meet
at the sagittal suture.
- lambdoid suture - extends across the back
of the head. Each parietal bone plate meets the
occipital bone plate at the lambdoid suture.
Sutures allow the bones to move during the birth
process. They act like an expansion joint, allowing
the bone to enlarge evenly as the brain grows and
the skull expands, resulting in a symmetrically shaped
head. However, if any of the sutures close too early
(fuse prematurely), there may be no growth in that
area. This may force growth to occur in another area
or direction, resulting in an abnormal head shape.
What are fontanelles?
There are two fontanelles (the space between the
bones of an infant's skull where the sutures intersect)
that are covered by tough membranes. The fontanelles
include:
- anterior fontanelle (Also called soft spot.)
- the junction where the two frontal and two parietal
bones meet. The anterior fontanelle remains soft
until about 2 years of age.
- posterior fontanelle - the junction of
the two parietal bones and the occipital bone. The
posterior fontanelle usually closes first, before
the anterior fontanelle, during the first several
months of an infant's life.
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