Fundamentals of Anatomy and Physiology

148

mastication or chewing and muscles for head movement
attach to certain cranial bones. At certain locations, air
sinuses or cavities are present that connect with the na-sal
cavities (Figure 7-8). All of the individual bones of the

Chapter 7

cranium are united by immovable junction lines called

sutures.

The frontal bone is a single bone that forms the fore-

head, the roof of the nasal cavity, and the orbits, which

Frontal sinus^

Ethmoidal

sinuses^

Sphenoidal

sinus^

Maxillary

sinus

(A)

External

auditory canal

Malleus (^) Incus
Stapes
Semicircular canals
(^) ®
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Ampulla
Tympanic
membrane
Eustachian
tube
Vestibule
Cochlea
Oval window
Round window
Lobule
External ear Middle ear Inner ear
(B)
(^) ®
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Figure 7- 8 (A) The paranasal sinuses. (B) Cross section of the ear showing the
ossicles.