Chapter 8
Skeletal System
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 1
Introduction

Skeletal tissues form bones—the organs of
the skeletal system

The relationship of bones to each other and
to other body structures provides a basis for
understanding the function of other organ
systems

The adult skeleton is composed of 206
separate bones
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Slide 2
Divisions of Skeleton

Axial skeleton—the 80 bones of the head,
neck, and torso; composed of 74 bones that
form the upright axis of the body and six tiny
middle ear bones
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 3
Divisions of Skeleton

Appendicular
skeleton—the 126
bones that form the
appendages to the axial
skeleton; the upper and
lower extremities
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Slide 4
Axial Skeleton

Skull—made up of 28 bones in two major divisions:
cranial bones and facial bones (Figures 8-2 to 8-7;
Table 8-3)
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 5
Cranial bones
• Frontal bone

Forms the forehead
and anterior part of
the top
of the cranium

Contains the frontal
sinuses

Forms the upper
portion of the orbits

Forms the coronal
suture with the two
parietal bones
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 6
Cranial bones
• Parietal bones

Form the bulging top
of the cranium

Form several sutures:
lambdoidal suture with
occipital bone;
squamous suture with
temporal bone and
part of sphenoid; and
coronal suture with
frontal bone
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 7
Cranial bones
• Temporal bones

Form the lower sides
of the cranium and
part
of the cranial floor

Contain the inner and
middle ears
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 8
Cranial bones
• Occipital bone

Forms the lower,
posterior part of the
skull

Forms immovable
joints with three other
cranial bones
and a movable joint
with the first cervical
vertebra
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 9
Cranial bones
• Sphenoid bone

A bat-shaped bone
located in the central
portion of the cranial
floor

Anchors the frontal,
parietal, occipital, and
ethmoid bones and
forms part of the
lateral wall of the
cranium and part
of the floor of each
orbit (Figure 8-7)

Contains the sphenoid
sinuses
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 10
Cranial bones
• Ethmoid bone

A complicated,
irregular bone that lies
anterior to the
sphenoid and
posterior to the nasal
bones

Forms the anterior
cranial floor, medial
orbit walls, upper
parts of the nasal
septum, and sidewalls
of the nasal cavity

The cribriform plate is
located in the ethmoid
Mosby items and derived items © 2007, 2003 by Mosby, Inc.
Slide 11