BSC 215 Lecture Notes - Lecture 17: Paranasal Sinuses, Cranial Vault

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Skull: Cranium and Facial Bones
The skull consists of 8 cranial bones and 14 facial bones. The bones are listed in
Table , but note that only six types of cranial bones and eight types of facial bones are
listed because some of the bones (as indicated in the table) exist as pairs.
The bones of the skull provide protection for the brain and the organs of
vision, taste, hearing, equilibrium, and smell. The bones also provide
attachment for muscles that move the head and control facial expressions
and chewing.
Figures 1 and 2 illustrate specific characteristics of these bones, while some
general features of the skull follow:
Sutures are immovable interlocking joints that join skull bones
together.
Fontanels are spaces between cranial bones that are filled with fibrous
membranes. The spaces provide pliability for the skull when it passes
through the birth canal and for brain growth during infancy. Bone
growth eventually fills the spaces by age two.
Sutural (Wormian) bones are very small bones that develop within
sutures. Their number and location vary.
The cranial vault denotes the top, sides, front, and back of the
cranium. The cranial floor (base) denotes the bottom of the cranium.
Cranial fossae are three depressions in the floor of the cranium. These
fossae, called the anterior, middle, and posterior cranial fossae,
provide spaces that accommodate the shape of the brain.
The nasal cavity is formed by cartilage and several bones. Air entering
the cavity is warmed and cleansed by mucus lining the cavity.
Sinuses (paranasal sinuses) are mucuslined cavities inside cranial and
facial bones that surround the nasal cavity. The cavities secrete mucus
that drains into the nasal cavity. The cavities also act as resonance
chambers that enhance vocal (and singing) quality.
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Document Summary

The skull consists of 8 cranial bones and 14 facial bones. Table , but note that only six types of cranial bones and eight types of facial bones are listed because some of the bones (as indicated in the table) exist as pairs. The bones of the skull provide protection for the brain and the organs of vision, taste, hearing, equilibrium, and smell. The bones also provide attachment for muscles that move the head and control facial expressions and chewing. The spaces provide pliability for the skull when it passes through the birth canal and for brain growth during infancy. Bone growth eventually fills the spaces by age two: sutural (wormian) bones are very small bones that develop within sutures. Their number and location vary: the cranial vault denotes the top, sides, front, and back of the cranium. The cranial floor (base) denotes the bottom of the cranium: cranial fossae are three depressions in the floor of the cranium.

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