Lecture Medical assisting: Administrative and clinical procedures with anatomy and physiology (4/e) – Chapter 21

CHAPTER

21
The Skeletal
System

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21­2

Learning Outcomes
21.1 Describe the parts of a long bone.
21.2 List the substances that make up bone
tissue.
21.3 List the functions of bones.
21.4 Identify bones by their classifications.
21.5 Describe how long bones grow.

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21­3

Learning Outcomes (cont.)
21.6 List and describe the skeletal
structures and one location of each
structure.
21.7 List the bones of the skull, spinal
column, rib cage, shoulders, arms,
hands, hips, legs, and feet. Describe

the location of each bone.
21.8 Define fontanels and explain their
importance.
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21­4

Learning Outcomes (cont.)
21.9 Describe the three major types of
joints and give examples of each.
21.10 Describe the structure of a synovial
joint.
21.11 Describe the causes, signs and
symptoms, and treatments of various
diseases and disorders of the skeletal
system.
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21­5

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

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21­6

The Skeletal System

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21­7

Bone Structure
•

Bones contain various
kinds of tissues,
Compact Bone
including
–
–
–

•

Osseous tissue
Blood vessels
Nerves

Spongy 
Bone

Osseous tissue can
appear compact or
spongy

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21­8

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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21­9

Bone Structure (cont.)

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21­10

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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21­11

Gender Differences
• Male Skull

• Male pelvic bones

– Larger and heavier

– Heavier and thicker

– Forehead shorter

– Obturator foramina
and acetabula are
larger and closer
together

– Face less round
– Jaw larger
– Mastoid processes
more prominent

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21­12

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

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21­13

Apply Your Knowledge
Match bone to classification. ANSWER:
L
___

Humerus

L.

F
___

Rib S.

Short bones

L
___

Femur

F.

___
I

Pelvic bones
Irregular bones

I.

___

Carpals

___

Frontal bone

___

Vertebra

Very
Good!

___

Tarsals

S
F
I

S

Long bones
Flat bones

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21­14

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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21­15

Functions of Bones (cont.)
•

Red bone marrow of
bone produces new
blood cells –
hematopoiesis

•

Store calcium

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21­16

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!

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21­17

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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21­18

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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21­19

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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21­20

Bone Tests
•

Bone density

•

Bone scans

•

Diagnose causes of





Bone pain
Arthritis
Bone infections
Bone cancers
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21­21

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 bone and secondary ossification occurs in the
epiphysis.

Good Job!
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21­22

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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21­23

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

Fossa

A relatively deep pit or depression

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21­24

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

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21­25

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
___

E. A projection situated above a condyle

D Tuberosity F. A prominent projection on a bone
___

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