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The femur, or thigh bone, has a diaphysis (shaft) with walls of compact bone and epiphyses filled with spongy bone. The body weight is transferred to the femur at the hip joint. Because the hip joint is off center relative to the axis of the shaft, the body weight is distributed along the bone in a way that compresses the medial (inner) portion of the shaft and stretches the lateral (outer) portion.

Fundamentals of Anatomy & Physiology

Eleventh Edition

Chapter 6

Bones and Bone Structure

 

 

 

Lecture Presentation by

Deborah A. Hutchinson

Seattle University

© 2018 Pearson Education, Inc.

 

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Learning Outcomes

6-1 Describe the major functions of the skeletal system.

6-2 Classify bones according to shape and structure, giving examples of each type, and explain the functional significance of each of the major types of bone markings.

6-3 Identify the cell types in bone, and list their major functions.

6-4 Compare the structures and functions of compact bone and spongy bone.

6-5 Compare the mechanisms of endochondral ossification and intramembranous ossification.

© 2018 Pearson Education, Inc.

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Learning Outcomes

6-6 Describe the remodeling and homeostatic mechanisms of the skeletal system.

6-7 Discuss the effects of exercise, nutrition, and hormones on bone development and on the skeletal system.

6-8 Explain the role of calcium as it relates to the skeletal system.

6-9 Describe the types of fractures, and explain how fractures heal.

6-10 Summarize the effects of the aging process on the skeletal system.

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6-1 Functions of Skeletal System

Skeletal system includes

Bones of the skeleton

Cartilages, ligaments, and other connective tissues

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6-1 Functions of Skeletal System

Primary functions of the skeletal system

Support

Storage of minerals and lipids

Blood cell production

Protection

Leverage

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6-2 Classification of Bones

Bones are classified by their

Shape

Structure

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6-2 Classification of Bones

Bone shapes

Sutural

Irregular

Short

Flat

Long

Sesamoid

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Figure 6–1 A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Sutural Bones

Sutural bone

Sutural bones, or

Wormian bones, are

small, flat, oddly

shaped bones found

between the flat bones

of the skull. They range

in size from a grain of

sand to a quarter. Their

borders are like pieces

of a jigsaw puzzle.

Posterior view

Flat Bones

Flat bones have thin, parallel surfaces. Flat

bones form the roof of the skull, the sternum

(breastbone), the ribs, and the scapulae

(shoulder blades). They provide protection for

underlying soft tissues and offer an extensive

surface area for the attachment

of skeletal muscles.

Parietal bone

Sectional

view

Irregular Bones

Irregular bones have

complex shapes with

short, flat, notched, or

ridged surfaces. The

vertebrae that form the

spinal column, the bones

of the pelvis, and several

bones in the skull are

examples of irregular bones.

Long Bones

Long bones are relatively

long and slender. They are

located in the arm and

forearm, thigh and leg,

palms, soles, fingers, and

toes. The femur, the long

bone of the thigh, is the

largest and heaviest bone in

the body.

Vertebra

Humerus

Short Bones

Short bones are

boxlike in

appearance.

Examples of short

bones include the

carpal bones (wrists)

and tarsal bones

(ankles).

Sesamoid Bones

Carpal

bones

Patella

Sesamoid bones are

usually small, round, and

flat. They are found near

joints of the knees, hands,

and feet. Few people have

sesamoid bones at every

possible location, but

everyone has sesamoid

patellae (pa-TEL-ē;

singular, patella, a small

shallow dish), or kneecaps.

Sutures

 

a

 

b

 

c

 

d

 

e

 

f

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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6-2 Classification of Bones

Sutural bones (Wormian bones)

Small, flat, irregularly shaped bones

Between flat bones of the skull

Number varies among individuals

Irregular bones

Have complex shapes

Examples: spinal vertebrae, pelvic bones

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© 2018 Pearson Education, Inc.

 

Figure 6–1a A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Sutural Bones

Sutural bone

Sutural bones, or

Wormian bones, are

small, flat, oddly shaped

bones found between

the flat bones of the

skull. They range in size

from a grain of sand to a

quarter. Their borders

are like pieces of a

jigsaw puzzle.

Sutures

Posterior view

 

a

 

 

 

 

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Figure 6–1b A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Irregular Bones

Irregular bones have

complex shapes with

short, flat, notched, or

ridged surfaces. The

vertebrae that form the

spinal column, the bones

of the pelvis, and several

bones in the skull are

examples of irregular bones.

Vertebra

 

b

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6-2 Classification of Bones

Short bones

Boxy

Examples: carpal bones and tarsal bones

Flat bones

Thin with parallel surfaces

Examples: bones of skull roof, sternum, ribs, and scapulae

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Figure 6–1c A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Short Bones

Short bones are

boxlike in

appearance.

Examples of short

bones include the

carpal bones

(wrists) and tarsal

bones (ankles).

Carpal

bones

 

c

 

 

 

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Figure 6–1d A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Flat Bones

Flat bones have thin, parallel surfaces. Flat bones

form the roof of the skull, the sternum (breastbone),

the ribs, and the scapulae (shoulder blades). They

provide protection for underlying soft tissues and

offer an extensive surface area for the attachment

of skeletal muscles.

Parietal bone

Sectional

view

 

d

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6-2 Classification of Bones

Long bones

Long and slender

Found in arms, legs, palms, soles, fingers, toes

Sesamoid bones

Usually small, round, and flat

Develop within tendons near joints of knees, hands, and feet

Location and number vary between individuals

Example: patellae

© 2018 Pearson Education, Inc.

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Figure 6–1e A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

 

e

Long bones are relatively

long and slender. They are

located in the arm and

forearm, thigh and leg,

palms, soles, fingers, and

toes. The femur, the long

bone of the thigh, is the

largest and heaviest bone in the body.

Humerus

Long Bones

 

 

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Figure 6–1f A Classification of Bones by Shape.

© 2018 Pearson Education, Inc.

Sesamoid Bones

Patella

Sesamoid bones are

usually small, round, and

flat. They are found near

joints of the knees, hands,

and feet. Few people have

sesamoid bones at every

possible location, but

everyone has sesamoid

patellae (pa-TEL-ē;

singular, patella, a small

shallow dish), or kneecaps.

 

f

 

 

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6-2 Classification of Bones

Bone markings (surface features)

Projections

Where muscles, tendons, and ligaments attach

At articulations with other bones

Openings and depressions

For passage of blood vessels and nerves

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Figure 6–2 An Introduction to Bone Markings (Part 1 of 2).

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Openings

Sinus:

Chamber within

a bone, normally

filled with air

Projections

Process:

Projection or

bump

Ramus:

Part of a bone

that forms an

angle with the

rest of the

structure

Skull, anterior view

Foramen:

Rounded

passageway for

blood vessels

and/or nerves

Fissure:

Deep furrow,

cleft, or slit

Meatus:

Passage or

channel,

especially the

opening of a canal

Canal:

Duct or channel

Skull, lateral view

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Figure 6–2 An Introduction to Bone Markings (Part 2 of 2).

© 2018 Pearson Education, Inc.

Projections where

muscles, tendons, or

ligaments attach

Trochanter:

Crest:

Spine:

Head

Line:

Tubercle:

Pelvis

Neck

Prominent

ridge

Pointed

process

Low ridge

Small,

rounded

projection

Femur

Projections for forming joints

Head:

Expanded articular

end of an epiphysis,

often separated from

the shaft by a

narrower neck (see

Figure 6–3a)

Narrow connection

between the

epiphysis and

diaphysis (see

Figure 6–3a)

Neck:

Depressions

Sulcus:

Narrow

groove

Fossa:

Shallow

depression

Humerus

Tuberosity:

Rough

projection

Facet:

Small, flat

articular surface

Condyle:

Smooth, rounded

articular process

Condyle

Trochlea:

Smooth, grooved

articular process

shaped like a pulley

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Large, rough

projection

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6-2 Classification of Bones

Structure of a long bone

Diaphysis (shaft)

Wall of compact bone

Central space called medullary cavity (marrow cavity)

Epiphysis (wide part at each end)

Mostly spongy bone (trabecular bone)

Metaphysis

Where diaphysis and epiphysis meet

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Figure 6–3a Bone Structure.

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Epiphysis

Spongy

bone

Metaphysis

Compact

bone

Medullary

cavity

Diaphysis

(shaft)

Metaphysis

Epiphysis

The structure of a representative

long bone (the femur) in longitudinal

section

 

a

 

 

 

 

 

 

 

 

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6-2 Classification of Bones

Structure of flat bones

For example, parietal bones of the skull

Consist of spongy bone between two layers of compact bone (cortex)

Within the cranium, the layer of spongy bone is called the diploë

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Figure 6–3b Bone Structure.

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Cortex

(compact bone)

Diploë

(spongy bone)

The structure of a flat bone (the parietal bone)

 

b

 

 

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6-3 Bone Tissue

Bone tissue

Dense, supportive connective tissue

Contains specialized cells

Solid extracellular matrix with collagen fibers

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6-3 Bone Tissue

Characteristics of bone

Dense matrix due to deposits of calcium salts

Osteocytes (bone cells) within lacunae organized around blood vessels

Canaliculi

Narrow passageways that allow for exchange of nutrients, wastes, and gases

Periosteum

Covers outer surfaces of bones (except at joints)

Consists of outer fibrous and inner cellular layers

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6-3 Bone Tissue

Bone matrix

Calcium phosphate, Ca3(PO4)2 makes up almost two-thirds of bone mass

Interacts with calcium hydroxide, Ca(OH)2, to form crystals of hydroxyapatite, Ca10(PO4)6(OH)2

Incorporates other calcium salts such as calcium carbonate (CaCO3) and ions (e.g., magnesium)

A bone lacking a calcified matrix looks normal, but is very flexible

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Figure 6–4 Bone Lacking a Calcified Matrix.

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6-3 Bone Tissue

Bone matrix

Matrix proteins

About one-third of bone mass is collagen fibers

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6-3 Bone Tissue

Bone cells

Make up only 2 percent of bone mass

Four types

Osteogenic cells

Osteoblasts

Osteocytes

Osteoclasts

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Figure 6–5 Types of Bone Cells.

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Types of Bone Cells

Endosteum

Osteogenic

cell

Medullary

cavity

Osteogenic cell: Stem

cell whose divisions

produce osteoblasts

Osteoblast: Immature

bone cell that secretes

organic components of

matrix

Medullary

cavity

Ruffled

border

Osteoclast

Matrix

Osteoblast

Osteoid

Matrix

Matrix

Osteocyte

Canaliculi

Osteocyte: Mature bone

cell that maintains the bone

matrix

Osteoclast: Multinucleate

cell that secretes acids and

enzymes to dissolve bone

matrix

 

a

 

b

 

c

 

d

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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6-3 Bone Tissue

Osteogenic cells (osteoprogenitor cells)

Mesenchymal cells that divide to produce osteoblasts

Located in inner cellular layer of periosteum and in endosteum

Assist in fracture repair

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Figure 6–5a Types of Bone Cells.

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Endosteum

Osteogenic

cell

Medullary

cavity

Osteogenic cell: Stem

cell whose divisions

produce osteoblasts

 

a

 

 

 

 

 

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6-3 Bone Tissue

Osteoblasts

Immature cells that produce new bone matrix during osteogenesis (ossification)

Osteoid—matrix produced by osteoblasts that has not yet become calcified

Osteoblasts surrounded by bone matrix become osteocytes

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Figure 6–5b Types of Bone Cells.

© 2018 Pearson Education, Inc.

 

b

Osteoblast

Osteoid

Matrix

Osteoblast: Immature

bone cell that secretes

organic components of

matrix

 

 

 

 

 

 

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6-3 Bone Tissue

Osteocytes

Mature bone cells that do not divide

Live in lacunae between layers of matrix

Have cytoplasmic extensions that pass through canaliculi

Two major functions

Maintain protein and mineral content of matrix

Help repair damaged bone

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Figure 6–5c Types of Bone Cells.

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c

Matrix

Osteocyte

Canaliculi

Osteocyte: Mature bone

cell that maintains the

bone matrix

 

 

 

 

 

 

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6-3 Bone Tissue

Osteoclasts

Absorb and remove bone matrix

Large, multinucleate cells

Secrete acids and protein-digesting enzymes

Dissolve bone matrix and release stored minerals

This osteolysis is important in homeostasis

Derived from the same stem cells that produce monocytes and macrophages

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Figure 6–5d Types of Bone Cells.

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d

Medullary

cavity

Ruffled

border

Osteoclast

Matrix

Osteoclast: Multinucleate

cell that secretes acids and

enzymes to dissolve bone

matrix

 

 

 

 

 

 

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6-4 Compact Bone and Spongy Bone

Osteon—functional unit of compact bone

Central canal contains blood vessel(s)

Perforating canals

Perpendicular to surface of bone

Carry blood vessels into deep bone and marrow

Lamellae—layers of bone matrix

Concentric lamellae surround central canal

Interstitial lamellae fill spaces between osteons

Circumferential lamellae are at outer and inner bone surfaces

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Figure 6–6 Osteons of Compact Bone.

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Osteon

Lacunae

Central canal

Lamellae

Osteons

SEM × 182

 

 

 

 

 

 

 

 

 

 

 

 

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Figure 6–7a The Structure of Compact Bone.

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Venule

Capillary

Periosteum

Concentric

lamellae

Interstitial

lamellae

Circumferential

lamellae

Osteons

Perforating fibers

Endosteum

Central

canal

Concentric

lamellae

Trabeculae of

spongy bone

(see Figure 6–8)

The organization of osteons

and lamellae in compact bone

Perforating

canal

Central

canal

Arteriole

 

a

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Vein

Artery

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Figure 6–7b The Structure of Compact Bone.

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Collagen

fiber

orientation

The orientation of collagen

fibers in adjacent lamellae

of an osteon

 

b

 

43

6-4 Compact Bone and Spongy Bone

Spongy bone lacks osteons

Matrix forms an open network of trabeculae

Lacks capillaries and venules

Red bone marrow fills spaces between trabeculae

Forms blood cells

Contains blood vessels that supply nutrients to osteocytes by diffusion

Yellow bone marrow

Found in other sites of spongy bone

Stores fat

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Figure 6–8 The Structure of Spongy Bone.

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Trabeculae of

spongy bone

Canaliculi

opening

on surface

Lamellae

Endosteum

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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6-4 Compact Bone and Spongy Bone

Weight-bearing bones

Trabeculae in epiphysis of femur transfer forces from pelvis to compact bone of femoral shaft

Medial side of shaft compresses

Causing tension on the lateral side

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© 2018 Pearson Education, Inc.

 

Figure 6–9 The Distribution of Forces on a Long Bone.

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Body weight (applied force)

Tension on lateral

side of shaft

Compression on

medial side of shaft

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The femur, or thigh bone, has a diaphysis (shaft) with walls of compact bone and epiphyses filled with spongy bone. The body weight is transferred to the femur at the hip joint. Because the hip joint is off center relative to the axis of the shaft, the body weight is distributed along the bone in a way that compresses the medial (inner) portion of the shaft and stretches the lateral (outer) portion.

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6-4 Compact Bone and Spongy Bone

Periosteum—membrane that covers outside of bones

Except within joint cavities

Outer, fibrous layer and inner, cellular layer

Fibers are interwoven with those of tendons

Perforating fibers—fibers that become incorporated into bone tissue

Increase strength of attachments

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6-4 Compact Bone and Spongy Bone

Functions of periosteum

Isolates bone from surrounding tissues

Provides a route for blood vessels and nerves

Participates in bone growth and repair

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Figure 6–10a The Periosteum and Endosteum.

© 2018 Pearson Education, Inc.

 

a

Circumferential

lamellae

Periosteum

Fibrous layer

Cellular layer

Canaliculi

Osteocyte

in lacuna

Perforating

fibers

The periosteum contains outer (fibrous) and

inner (cellular) layers. Collagen fibers of the

periosteum are continuous with those of the

bone, adjacent joint capsules, and attached

tendons and ligaments.

 

 

 

 

 

 

 

 

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6-4 Compact Bone and Spongy Bone

Endosteum—incomplete cellular layer that lines medullary cavity

Active during bone growth, repair, and remodeling

Covers trabeculae of spongy bone

Lines central canals of compact bone

Consists of flattened layer of osteogenic cells

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