The document summarizes key aspects of the skeletal system including: - The skeletal system has 206 bones and is divided into the axial skeleton and appendicular skeleton. - Bones provide structure, protection, movement, mineral storage, and blood cell formation. There are four classifications of bones based on shape: long, short, flat, and irregular. - The axial skeleton forms the longitudinal body core and includes the skull, vertebral column, and thoracic cage. The skull has two sets of bones joined by sutures. - The vertebral column consists of vertebrae separated by intervertebral discs, and has a normal curvature.

1. Essentials of Human Anatomy & Physiology
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Seventh Edition
Elaine N. Marieb
Chapter 5
The Skeletal System

2. The Skeletal SystemThe Skeletal System
Slide 5.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Parts of the skeletal system
• Bones (skeleton)
• Joints
• Cartilages
• Ligaments (bone to bone)(tendon=bone to
muscle)
• Divided into two divisions
• Axial skeleton
• Appendicular skeleton – limbs and girdle

4. Functions of BonesFunctions of Bones
Slide 5.2Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Support of the body
• Protection of soft organs
• Movement due to attached skeletal
muscles
• Storage of minerals and fats
• Blood cell formation

5. Bones of the Human BodyBones of the Human Body
Slide 5.3Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The skeleton has 206 bones
• Two basic types of bone tissue
•Compact bone
• Homogeneous
•Spongy bone
• Small needle-like
pieces of bone
• Many open spaces
Figure 5.2b

6. Classification of BonesClassification of Bones
Slide 5.4aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Long bones
•Typically longer than wide
•Have a shaft with heads at both ends
•Contain mostly compact bone
• Examples: Femur, humerus

7. Classification of BonesClassification of Bones
Slide 5.4bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Short bones
•Generally cube-shape
•Contain mostly spongy bone
•Examples: Carpals, tarsals

8. Classification of Bones on theClassification of Bones on the
Basis of ShapeBasis of Shape
Slide 5.4cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.1

9. Classification of BonesClassification of Bones
Slide 5.5aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Flat bones
•Thin and flattened
•Usually curved
•Thin layers of compact bone around a layer
of spongy bone
•Examples: Skull, ribs, sternum

10. Classification of BonesClassification of Bones
Slide 5.5bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Irregular bones
•Irregular shape
•Do not fit into other bone classification
categories
•Example: Vertebrae and hip

11. Classification of Bones on theClassification of Bones on the
Basis of ShapeBasis of Shape
Slide 5.5cCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.1

12. Gross Anatomy of a Long BoneGross Anatomy of a Long Bone
Slide 5.6Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Diaphysis
•Shaft
•Composed of
compact bone
• Epiphysis
•Ends of the bone
•Composed mostly of
spongy bone Figure 5.2a

13. Structures of a Long BoneStructures of a Long Bone
Slide 5.7Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Periosteum
• Outside covering of
the diaphysis
• Fibrous connective
tissue membrane
• Sharpey’s fibers
• Secure periosteum to
underlying bone
• Arteries
• Supply bone cells
with nutrients
Figure 5.2c

14. Structures of a Long BoneStructures of a Long Bone
Slide 5.8aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Articular cartilage
•Covers the
external surface of
the epiphyses
•Made of hyaline
cartilage
•Decreases friction
at joint surfaces Figure 5.2a

15. Structures of a Long BoneStructures of a Long Bone
Slide 5.8bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Medullary cavity
•Cavity of the shaft
•Contains yellow
marrow (mostly fat)
in adults
•Contains red marrow
(for blood cell
formation) in infants Figure 5.2a

16. Bone Markings - Page 119Bone Markings - Page 119
Slide 5.9Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Surface features of bones
• Sites of attachments for muscles, tendons,
and ligaments
• Passages for nerves and blood vessels
• Categories of bone markings
• Projections and processes – grow out from the
bone surface
• Depressions or cavities – indentations

17. Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Osteon (Haversian System)
• A unit of bone
• Central (Haversian) canal
• Opening in the center of an osteon
• Carries blood vessels and nerves
• Perforating (Volkman’s) canal
• Canal perpendicular to the central canal
• Carries blood vessels and nerves

18. Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.3

19. Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Lacunae
• Cavities containing
bone cells
(osteocytes)
• Arranged in
concentric rings
• Lamellae
• Rings around the
central canal
• Sites of lacunae Figure 5.3

20. Microscopic Anatomy of BoneMicroscopic Anatomy of Bone
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Canaliculi
•Tiny canals
•Radiate from the
central canal to
lacunae
•Form a transport
system
Figure 5.3

21. Changes in the Human SkeletonChanges in the Human Skeleton
Slide 5.12Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• In embryos, the skeleton is primarily hyaline
cartilage
• During development, much of this cartilage
is replaced by bone
• Cartilage remains in isolated areas
• Bridge of the nose
• Parts of ribs
• Joints

22. Bone GrowthBone Growth
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Epiphyseal plates allow for growth of long
bone during childhood
•New cartilage is continuously formed
•Older cartilage becomes ossified
•Cartilage is broken down
•Bone replaces cartilage

23. Bone GrowthBone Growth
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Bones are remodeled and lengthened
until growth stops
•Bones change shape somewhat
•Bones grow in width

24. Long Bone Formation and GrowthLong Bone Formation and Growth
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.4a

25. Types of Bone CellsTypes of Bone Cells
Slide 5.15Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Osteocytes
• Mature bone cells
• Osteoblasts
• Bone-forming cells
• Osteoclasts
• Bone-destroying cells
• Break down bone matrix for remodeling and
release of calcium
• Bone remodeling is a process by both
osteoblasts and osteoclasts

26. Bone FracturesBone Fractures
Slide 5.16Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• A break in a bone
• Types of bone fractures
• Closed (simple) fracture – break that does not
penetrate the skin
• Open (compound) fracture – broken bone
penetrates through the skin
• Bone fractures are treated by reduction
and immobilization
• Realignment of the bone

27. Common Types of FracturesCommon Types of Fractures
Slide 5.17Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Table 5.2

28. Repair of Bone FracturesRepair of Bone Fractures
Slide 5.18Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Hematoma (blood-filled swelling) is
formed
• Break is splinted by fibrocartilage to
form a callus
• Fibrocartilage callus is replaced by a
bony callus
• Bony callus is remodeled to form a
permanent patch

29. Stages in the Healing of a BoneStages in the Healing of a Bone
FractureFracture
Slide 5.19Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.5

30. The Axial SkeletonThe Axial Skeleton
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Forms the longitudinal part of the body
• Divided into three parts
•Skull
•Vertebral column
•Bony thorax

31. The Axial SkeletonThe Axial Skeleton
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.6

32. The SkullThe Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Two sets of bones
•Cranium
•Facial bones
• Bones are joined by sutures
• Only the mandible is attached by a
freely movable joint

33. The SkullThe Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.7

34. Bones of the SkullBones of the Skull
Slide 5.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.11

35. Human Skull, Superior ViewHuman Skull, Superior View
Slide 5.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.8

36. Human Skull, Inferior ViewHuman Skull, Inferior View
Slide 5.24Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.9

37. Paranasal SinusesParanasal Sinuses
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Hollow portions of bones surrounding
the nasal cavity
Figure 5.10

38. Paranasal SinusesParanasal Sinuses
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Functions of paranasal sinuses
• Lighten the skull
• Give resonance and amplification to voice
Figure 5.10

39. The Hyoid BoneThe Hyoid Bone
Slide 5.26Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The only bone that
does not articulate
with another bone
• Serves as a
moveable base for
the tongue
Figure 5.12

40. The Fetal SkullThe Fetal Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The fetal skull is
large compared
to the infants
total body length
Figure 5.13

41. The Fetal SkullThe Fetal Skull
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Fontanelles –
fibrous membranes
connecting the
cranial bones
• Allow the brain
to grow
• Convert to bone
within 24 months
after birth
Figure 5.13

42. The Vertebral ColumnThe Vertebral Column
Slide 5.28Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Vertebrae
separated by
intervertebral discs
• The spine has a
normal curvature
• Each vertebrae is
given a name
according to its
location Figure 5.14

43. Structure of a Typical VertebraeStructure of a Typical Vertebrae
Slide 5.29Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.16

44. The Bony ThoraxThe Bony Thorax
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Forms a
cage to
protect
major
organs
Figure 5.19a

45. The Bony ThoraxThe Bony Thorax
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Made-up of
three parts
•Sternum
•Ribs
•Thoracic
vertebrae
Figure 5.19a

46. The Appendicular SkeletonThe Appendicular Skeleton
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Limbs (appendages)
• Pectoral girdle
• Pelvic girdle

47. The Appendicular SkeletonThe Appendicular Skeleton
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.6c

48. The Pectoral (Shoulder) GirdleThe Pectoral (Shoulder) Girdle
Slide 5.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Composed of two bones
•Clavicle – collarbone
•Scapula – shoulder blade
• These bones allow the upper limb to
have exceptionally free movement

49. Bones of the Shoulder GirdleBones of the Shoulder Girdle
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.20a, b

50. Bones of the Upper LimbBones of the Upper Limb
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The arm is
formed by a
single bone
•Humerus
Figure 5.21a, b

51. Bones of the Upper LimbBones of the Upper Limb
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The forearm
has two bones
• Ulna
• Radius
Figure 5.21c

52. Bones of the Upper LimbBones of the Upper Limb
Slide 5.36Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The hand
•Carpals – wrist
•Metacarpals –
palm
•Phalanges –
fingers
Figure 5.22

53. Bones of the Pelvic GirdleBones of the Pelvic Girdle
Slide 5.37Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Hip bones
• Composed of three pair of fused bones
• Ilium
• Ischium
• Pubic bone
• The total weight of the upper body rests on the
pelvis
• Protects several organs
• Reproductive organs
• Urinary bladder
• Part of the large intestine

54. The PelvisThe Pelvis
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.23a

55. Gender Differences of the PelvisGender Differences of the Pelvis
Slide 5.39Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.23c

56. Bones of the Lower LimbsBones of the Lower Limbs
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The thigh has
one bone
•Femur – thigh
bone
Figure 5.35a, b

57. Bones of the Lower LimbsBones of the Lower Limbs
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The leg has
two bones
•Tibia
•Fibula
Figure 5.35c

58. Bones of the Lower LimbsBones of the Lower Limbs
Slide 5.41Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The foot
•Tarsus – ankle
•Metatarsals –
sole
•Phalanges –
toes
Figure 5.25

59. JointsJoints
Slide 5.43Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Articulations of bones
• Functions of joints
•Hold bones together
•Allow for mobility
• Ways joints are classified
•Functionally
•Structurally

60. Functional Classification of JointsFunctional Classification of Joints
Slide 5.44Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Synarthroses – immovable joints
• Amphiarthroses – slightly moveable
joints
• Diarthroses – freely moveable joints

61. Structural Classification of JointsStructural Classification of Joints
Slide 5.45Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Fibrous joints
•Generally immovable
• Cartilaginous joints
•Immovable or slightly moveable
• Synovial joints
•Freely moveable

62. Fibrous JointsFibrous Joints
Slide 5.46Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Bones united by fibrous tissue –
synarthrosis or largely immovable.
Figure 5.27d, e

63. Cartilaginous Joints – mostlyCartilaginous Joints – mostly
amphiarthrosisamphiarthrosis
Slide 5.47Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Bones connected by cartilage
• Examples
•Pubic
symphysis
•Intervertebral
joints
Figure 5.27b, c

64. Synovial JointsSynovial Joints
Slide 5.48Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Articulating
bones are
separated by a
joint cavity
• Synovial fluid
is found in the
joint cavity
Figure 5.27f–h

65. Features of Synovial Joints-Features of Synovial Joints-
DiarthrosesDiarthroses
Slide 5.49Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Articular cartilage (hyaline cartilage)
covers the ends of bones
• Joint surfaces are enclosed by a fibrous
articular capsule
• Have a joint cavity filled with synovial
fluid
• Ligaments reinforce the joint

66. Structures Associated with theStructures Associated with the
Synovial JointSynovial Joint
Slide 5.50Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Bursae – flattened fibrous sacs
• Lined with synovial membranes
• Filled with synovial fluid
• Not actually part of the joint
• Tendon sheath
• Elongated bursa that wraps around a tendon

67. The Synovial JointThe Synovial Joint
Slide 5.51Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.28

68. Types of Synovial Joints Based onTypes of Synovial Joints Based on
ShapeShape
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.29a–c

69. Types of Synovial Joints Based onTypes of Synovial Joints Based on
ShapeShape
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 5.29d–f

70. Inflammatory ConditionsInflammatory Conditions
Associated with JointsAssociated with Joints
Slide 5.53Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Bursitis – inflammation of a bursa usually
caused by a blow or friction
• Tendonitis – inflammation of tendon sheaths
• Arthritis – inflammatory or degenerative
diseases of joints
• Over 100 different types
• The most widespread crippling disease in the
United States

71. Clinical Forms of ArthritisClinical Forms of Arthritis
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Osteoarthritis
• Most common chronic arthritis
• Probably related to normal aging processes
• Rheumatoid arthritis
• An autoimmune disease – the immune system
attacks the joints
• Symptoms begin with bilateral inflammation of
certain joints
• Often leads to deformities

74. Clinical Forms of ArthritisClinical Forms of Arthritis
SlideCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Gouty Arthritis
•Inflammation of joints is caused by a
deposition of urate crystals from the blood
•Can usually be controlled with diet