25-1
The Skeletal System
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-2
Learning Outcomes
1
Describe the parts of a long bone.
2
List the substances that make up bone tissue.
3
List the functions of bones.
4
Identify bones by their classifications.
5
Describe how long bones grow.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-3
Learning Outcomes (cont.)
6
List and describe the skeletal structures and
one location of each structure.
7
List the bones of the skull, spinal column, rib
cage, shoulders, arms, hands, hips, legs, and
feet. Describe the location of each bone.
8
Define fontanels and explain their importance.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-4
Learning Outcomes (cont.)
9
Describe the three major types of joints and
give examples of each.
10
Describe the structure of a synovial joint.
11
Describe the causes, signs and symptoms, and
treatments of various diseases and disorders of
the skeletal system.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-5
Introduction

Bones provide the
body with structure
and support

Divisions

Axial – 80 bones




206 bones with joints
and connective tissue

Skull
Vertebral column
Rib cage
Appendicular – 126
bones



Arms and legs
Pectoral girdle
Pelvic girdle
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-6
The Skeletal System
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-7
Bone Structure

Bones contain various kinds of tissues, including




Osseous tissue
Blood vessels
Nerves
Osseous tissue can
appear compact or
spongy
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25-8
Bone Structure (cont.)

Compact bone looks
solid


Structures can be
observed with a
microscope
All bones are made
up of both compact
and spongy bone
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25-9
Bone Structure (cont.)

Classification by shape

Long bones – located primarily in the arms and legs



Femur (thigh bone)
Humerus (upper arm bone)
Short bones – small bones
located in the wrists
and ankles


Carpals (wrist bones)
Tarsals (ankle bones)
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25-10
Bone Structure (cont.)

Flat bones – located in the
skull and rib cage



Ribs
Frontal bone
Irregular bones


Vertebrae
Bones of the pelvic girdle
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25-11
Bone Structure: Gender Differences

Male Skull

Male pelvic bones

Larger and heavier

Heavier and thicker

Forehead shorter


Face less round
Obturator foramina and
acetabula are larger
and closer together

Jaw larger

Mastoid processes
more prominent
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25-12
Bone Structure: Gender Differences
(cont.)

Male pelvic cavity



Narrower and longer
Less roomy and more
funnel shaped

Male coccyx

Less movable
Male sacrum



Narrower
Sacral promontory projects forward
Sacral curvature is less sharp posteriorly
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-13
Apply Your Knowledge
Match bone to classification. ANSWER:
___
L Humerus
___
F Rib
___
L Femur
L. Long bones
___
I
___
S
___
F
___
I
I. Irregular bones
Pelvic bones
Carpals
Frontal bone
S. Short bones
F. Flat bones
Very
Good!
Vertebra
___
S Tarsals
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25-14
Functions of Bones

Give shape to body parts

Support and protect soft structures


Examples – brain, lungs, heart
Allow body movement, because skeletal
muscles attach to them

Allow for voluntary movement
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25-15
Functions of Bones (cont.)

Red bone marrow of
bone produces new
blood cells –
hematopoiesis

Store calcium
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25-16
Apply Your Knowledge
Why is it important for the bones to store calcium?
ANSWER: Every cell in the body needs calcium, so the body
must have a large supply readily available.
Correct!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-17
Bone Growth

Ossification – process of bone
growth

Intramembranous ossification


Bones begin as tough, fibrous
membrane
Bone-forming cells called
osteoblasts turn the membrane to
bone (located in skull)
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25-18
Bone Growth (cont.)

Endochondral ossification


Bones begin as cartilage
models
Primary ossification center


Secondary ossification center



Bone formed in the diaphysis
Epiphyses turn to bone
Bones with some cartilage between an epiphysis and the
diaphysis will continue to grow
Medullary cavity and spaces in cancellous bone form

Cells that form holes in bone are called osteoclasts
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25-19
Bone Growth: Building Better Bones

Teach healthy behaviors
Bone-healthy diet with calcium and vitamin D
 Bone-health exercises

 Weight-bearing
 Strength

training
Bone-healthy lifestyle
 Avoid
smoking
 Avoid alcohol
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25-20
Bone Growth (cont.)

Bone tests
Bone density
 Bone scans

 Diagnose
causes of
Bone pain
 Arthritis
 Bone infections
 Bone cancers

© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-21
Apply Your Knowledge
What are the two types of bone growth?
ANSWER: Intramembranous ossification, in which bones
begin as tough membrane and are turned to bone by
osteoblasts, and endochondral ossification, in which
primary ossification occurs in the diaphysis of the of the
bone and secondary ossification occurs in the epiphysis.
Good Job!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-22
Bony Structures

Rigid foundation

Projections and processes for muscle and
ligament attachment

Depressions and hollows for articulations – the
connection of bones at joints

Openings for blood vessels and nerves
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25-23
Bony Structures (cont.)
Term
Definition
Condyle
A rounded process that usually articulates
with another bone
Crest
A narrow, ridge-like projection
Epicondyle
A projection situated above a condyle
Foramen
An opening through a bone that is usually a
passageway for blood vessels, nerves, or
ligaments
A relatively deep pit or depression
Fossa
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25-24
Bony Structures (cont.)
Term
Definition
Head
An enlargement on the end of a bone
Process
A prominent projection on a bone
Suture
An interlocking line of union between bones
Trochanter
A relatively large process
Tubercle
A small, knoblike process
Tuberosity
A knoblike process, usually larger than a
tubercle
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-25
The Skull

Two bone types:
Cranial – form the top, sides, and back of the
skull
 Facial – form the face

“Soft spots” felt on an infant's skull are
actually fontanels
 Tough membranes that connect the
incompletely developed bones
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-26
Apply Your Knowledge
Match the following:
ANSWER:
E Epicondyle A. A relatively deep pit or depression
___
C Fontanels
___
B. An interlocking line of union between bones
A Fossa
___
C. “Soft spots” felt on an infant’s skull
F Process
___
D. A knoblike process, usually larger than a tubercle
B Suture
___
D Tuberosity
___
E. A projection situated above a condyle
F. A prominent projection on a bone
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-27
The Skull: Cranial Bones

Frontal – anterior


Parietal – top and most
of the sides
Sphenoid and ethmoid
bones – floor

Ear ossicles are the
smallest bones of the
body


Occipital – back
Temporal – form the
lower sides of the skull



Malleus
Incus
Stapes
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25-28
The Skull (cont.)




Mandible – forms the lower
jaw bone
Maxillae – form the upper
jawbone


Palatine – form the
anterior portion of the
palate
Vomer – a thin bone that
divides the nasal cavity
Zygomatic – form the
prominence of the cheeks
Nasal bones – fuse together
to form the bridge of the
nose
Click to see Skull
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-30
Apply Your Knowledge
ANSWER:
Match the bones of the skull:
E Occipital
___
A. Form the upper jawbone
C Sphenoid
___
B. A thin bone that divides the nasal cavity
F Mandible
___
C. Part of floor of skull
A Maxillae
___
D. Form the prominence of the cheeks
D Zygomatic
___
E. Back of skull
B Vomer
___
F. Lower jaw bone
Very
Good!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-31
The Spinal
Column

7 cervical vertebrae

12 thoracic vertebrae

5 lumbar vertebrae

Sacrum

Coccyx
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25-32
The Spinal Column (cont.)

Cervical vertebrae




Smallest and lightest
Located in the neck
region
First one is atlas
Second one is axis

Thoracic vertebrae


Join the 12 pairs of ribs
Lumbar vertebrae

Have very sturdy
structures
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-33
The Spinal Column (cont.)

Sacrum


A triangular-shaped bone that consists of five fused
vertebrae
Coccyx



A small, triangular-shaped bone made up of 3 to 5 fused
vertebrae
Considered unnecessary
More commonly called the tailbone
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-34
Apply Your Knowledge
ANSWER:
Identify the
sections of the
spinal column
and give the
number of
vertebrae for
each.
Cervical – 7
Thoracic – 12
Lumbar – 5
Right!
Sacrum –
5 fused
Coccyx –
3 to 5 fused
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-35
The Rib Cage
Sternum





Breastplate
Forms the front middle
portion of the rib cage
Joins with the clavicles
and most ribs
Xyphoid process

Cartilaginous tip
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25-36
The Rib Cage (cont.)

12 pairs of ribs


All are attached
posteriorly to thoracic
vertebrae
True


First seven pairs of ribs
Attach to sternum by
costal cartilage

False



Rib pairs 8, 9, and 10
Attach to the costal
cartilage of rib pair 7
Floating


Rib pairs 11 and 12
Do not attach anteriorly
to any structure
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-37
Apply Your Knowledge
True or False:
ANSWER:
T The sternum forms the front middle portion of the rib cage.
___
F The xyphoid process is a boney tip of the sternum.
___
cartilaginous
___
F The true ribs are the first five pairs of ribs.
seven
___
T False ribs attach to the costal cartilage of rib pair seven.
F Floating ribs attach to the xyphoid process.
___
do not attach anteriorly to any structure.
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-38
Bones of the Shoulders, Arms,
and Hands

Shoulders – pectoral girdles



Clavicles
Scapulae
Upper limb or arm bones



Humerus
Radius
Ulna
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25-39
Bones of the Shoulders, Arms, and
Hands (cont.)

Hand



8 carpals per hand
5 metacarpals per hand
14 phalanges per hand


3 in each finger
2 in each thumb
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-40
Apply Your Knowledge
Match the following:
ANSWER:
___
A Clavicle
A. Pectoral girdle
B Radius
___
B. Arm bones
B Humerus
___
C. Hands
___
C Carpals
A Scapula
___
B Ulna
___
___
C Phalanges
C Metacarpals
___
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25-41
Bones of the Hips, Legs,
and Feet

Hipbones

Coxal bones form
the pelvic girdle



Ilium
Ischium
Pubis
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25-42
Bones of the Hips, Legs,
and Feet (cont.)

Bones of leg




Femur
Patella
Tibia
Fibula
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25-43
Bones of the Hips, Legs,
and Feet (cont.)

Bones of the foot



Tarsals
Metatarsals
Phalanges
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-44
Apply Your Knowledge
Match the following:
A. Coxal bones
B Tibia
___
A Ilium
___
B Femur
___
A Pubis
___
___
C Calcaneus
ANSWER:
B. Leg bones
B Patella
___
C. Foot bones
A Ischium
___
C Metatarsals
___
B Fibula
___
___
C Tarsals
Super!
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25-45
Joints


Junctions between bones
Classification based on
structure

Fibrous joints



Connected together with
short fibers
Between cranial bones and
facial bones
Sutures – fibrous joints in
the skull
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25-46
Joints

Cartilaginous
joints


Connected
together with a
disc of cartilage
Between vertebrae
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25-47
Joints

Synovial joints


Covered with hyaline cartilage
Held together by a fibrous joint
capsule lined with synovial
membrane



Secretes synovial fluid so bones
move easily against each other
Freely movable
Bones are also held together through tough, cord-like
structures called ligaments
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-48
Apply Your Knowledge
Match the following:
ANSWER:
A. Fibrous joints B. Cartilaginous joints C. Synovial joints
A Between cranial bones and facial bones
____
C Covered with hyaline cartilage
____
B Between vertebrae
____
C Freely movable
____
A Sutures in the skull
____
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25-49
Common Diseases and Disorders

Arthritis – general term meaning joint
inflammation

Osteoarthritis – degenerative joint disease,
primarily of weight-bearing joints

Rheumatoid Arthritis – chronic systemic
inflammatory disease of smaller joints and
surrounding tissues
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25-50
Common Diseases and Disorders
(cont.)

Bursitis – inflammation of a bursa (fluid-filled sac
that cushions tendons)

Carpal Tunnel Syndrome – overuse of wrist; the
median nerve in the wrist becomes compressed

Ewing’s Family of Tumors (EFT) – a group of
tumors that affect different tissue types; primarily
bone
Gout – a type of arthritis; deposits of uric acid
crystals in the joints

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25-51
Common Diseases and Disorders
(cont.)

Kyphosis – abnormal curvature of the spine
(humpback)

Lordosis – exaggerated inward curvature of the
lumbar spine (swayback)

Osteogenesis imperfecta – brittle-bone disease

Osteoporosis – a condition in which bones thin
(become porous) over time
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25-52
Common Diseases and Disorders
(cont.)

Osteosarcoma – a type of bone cancer that originates
from osteoblasts, the cells that make bony tissue

Paget’s disease – causes bones to
enlarge and become deformed
and weak

Scoliosis – an abnormal
S-shaped curvature of the spine
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-53
Apply Your Knowledge
The doctor has told your patient that he has an
osteosarcoma. What do you know about this
disorder?
Osteosarcoma is a type of bone cancer that
originates from osteoblasts, the cells that make
bony tissue.
Nice Work!
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-54
In Summary

Skeletal system



Two divisions
Bone growth through ossification
Functions






Supports the body
Protects internal organs
Attachment for muscles for movement
Stores minerals
Produces new blood cells by hematopoiesis
Joined by three types of joints
© 2009 The McGraw-Hill Companies, Inc. All rights reserved
25-55
Rigid, the skeleton
of habit alone
upholds the
human frame.
~ Virginia Woolf
© 2009 The McGraw-Hill Companies, Inc. All rights reserved