1. Chapter 5 The Skeletal System
Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 5 The Skeletal System
Slides 5.1 – 5.15
Lecture Slides in PowerPoint by Jerry L. Cook
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2. The Skeletal System Consists of: Bones (skeleton) Joints Cartilages
Ligaments
Slide 5.1
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3. Functions of Bones
Support of soft tissues and maintains body’s shape and posture
Protection- soft organs
Serve as levers for the movement skeletal muscles
Storage of minerals (P, K+, Na+, Ca++)and energy (fats)
Blood cell formation - hematopoiesis
Slide 5.2
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4. Gross Anatomy of a Long Bone
Diaphysis
Shaft
Composed of compact bone
Metaphysis
Borderline between epiphysis and diaphysis
Epiphysis
Ends of the bone
Composed mostly of spongy bone
Figure 5.2a
Slide 5.6
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5. Gross Anatomy of a Long Bone
Periosteum
Dense white fibrious membrane covering bone
Functions- bone growth, nutritition, repair, and attachement site
Endosteum
Articular cartilage
Thin layer of hyaline cartilage
Covers ends of bones where joints form
Reduce friction during movement
Figure 5.2a
Slide 5.6

6. Gross Anatomy of a Long Bone
Medullary Cavity
w/in the diaphysis contains
yellow marrow – fat and a few blood cell (adults)
Infants – red marrow
Compact bone
Forms bulk of diaphysis and covers epiphysis
Spongy bone
Forms small portion of diaphysis at the ends of medullary cavity
Contains red bone marrow
Figure 5.2a
Slide 5.6
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7. Bones of the Human Body Two basic types of bone tissue Compact bone
Homogeneous
Spongy bone
Small needle-like pieces of bone
Many open spaces
Figure 5.2b
Slide 5.3
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8. Microscopic Anatomy of Bone
Osteon (Haversian System)
Structural unit of bone
Central (Haversian) canal
Opening in the center of an osteon
Carries bld. Vessels, lymphatic vessels, and nerves
Volkman’s (Perforating) canal
Canal perpendicular to the central canal
Carries blood vessels and nerves
Slide 5.10a
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9. Types of Bone Cells Osteoblasts – bone building cells
Osteocytes – bone maintaining cells
Osteoclasts – bone remodeling cells (remove bone; resorption)
Slide 5.2
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10. Microscopic Anatomy of Bone
Figure 5.3
Slide 5.10b
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11. Microscopic Anatomy of Bone
Lacunae
Cavities arranged in concentric rings
contain osteocytes
Lamellae
Rings of calcified matrix are around the central canal
Sites of lacunae
Figure 5.3
Slide 5.11a
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12. Microscopic Anatomy of Bone
Canaliculi
Radiate from the central canal to lacunae
Tiny canals that connect lacunae to haversian canal
Form a transport system
Figure 5.3
Slide 5.11b
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13. Bone Development (Osteogenesis/Ossification)
Embryonic Development – skeletal system => fibrous
membrane called hyaline cartilage
In young children – cartilage is replaced by bone.
Types of Ossification:
Intramembranous ossification
Bone forms from a fibrous membrane to form membrane
bone; occurs during embryonic development
forms flat bones, and some irregular bones
including bones of skull and clavicles
Slide 5.13a

14. Bone Development (Osteogenesis/Ossification)
Endochondrial ossification
bone forms from hyaline cartilage to form cartilage bone
occurs during 3rd month of embryonic development
by birth most hyaline cartilage-> bone except for
2 regions: 1. Articular cartilage
2.Epiphyseal plate

15. Bone Development Appositional Growth (thickness/diameter)
Osteoblasts secrete bony matrix on external surface of bone
(periosteum)
Osteoclasts destroy bone on the endosteal surface of compact bone.
Slide 5.13a

16. Bone Growth - longitudinally
Hyaline cartilage of epiphyseal plates grow by mitosis of the cell on the proximal face.
Hyaline cartilage at the distal face of plate (towards medullary cavity) mature and die, and matrix calcifies; osteoblasts invade to form spongy bone -> compact bone

17. Long bone growth is regulated by hormones:
1. growth hormone produced in pituitary gland
2. sex hormones produced by ovaries and testes
secreted during puberty and end during
adolescence when epiphyseal plates are converted to
bone (males – testosterone females – estrogen)

18. Bone Fractures - 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
Slide 5.16
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19. Common Types of Fractures
Table 5.2
Slide 5.17
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20. Repair of Bone Fractures
Formation of a Hematoma (blood-filled swelling)
Break is splinted by fibrocartilage to form a callus
Fibrocartilage callus is replaced by a bony callus
Bony callus is remodeled in response to mechanical stress to fracture to form a permanent patch

21. Stages in the Healing of a Bone Fracture
Figure 5.5
Slide 5.19
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22. Parathyroid hormone (PTH)
Bones are remodeled continually in response to 2 factors: 1. Pull of gravity and muscles on skeleton. 2. Ca++ levels in blood
If blood Ca , then
Parathyroid hormone (PTH)
activates
Osteoclasts
breaksdown bone matrix and releases Ca++ ions
If blood Ca++ , then Calcitonin (Thyroid gland) activates Osteoblasts deposits Ca++ ions into bone matrix

23. Bone Markings 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
Slide 5.9
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24. Classification of Bones
Long bones
longer than wide
Have a shaft with heads at both ends
Contain mostly compact bone
Examples: Femur, humerus
Slide 5.4a
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25. Classification of Bones
Short bones
cube-shape
mostly spongy bone
Examples: Carpals, tarsals
Slide 5.4b
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26. Classification of Bones
Flat bones
Thin and flattened
Usually curved
Thin layers of compact bone around a layer of spongy bone
Examples: Skull, ribs, sternum
Slide 5.5a
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27. Classification of Bones
Irregular bones
Irregular shapes
Do not fit into other bone classification categories
Example: Vertebrae and hip
Slide 5.5b
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28. The Skeletal System Consists of 206 bones: Divided into two divisions
(Informational)
Consists of 206 bones:
Divided into two divisions
Axial skeleton – 80 bones
Appendicular skeleton – 126 bones
Slide 5.1
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29. Axial skeleton – 80 bones (Informational) Consists of:
Skull – 22 bones
8 crainal bones
14 facial bones
hyoid bone – 1 bone
Auditory ossicles – 6 bones
stapes, incus, malleus
Vertebrae – 26 bones
Thorax – 25 bones
sternum
24 ribs
Slide 5.1
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30. Appendicular skeleton – 126 bones
Consists of:
Pectoral girdles – 4 bones
2 clavicles
2 scapulas
Upper extremities – 60 bones
2 humerus
2 ulnas
2 radius
16 carpals
10 metacarpals
28 phalanges
Pelvic girdle - 2 bones
Lower extremities - 60 bones
2 femurs metatarsals
2 fibulas phalanges
2 Tibias
2 Patellas
14 Tarsals
(Informational)
Slide 5.1

31. The Hyoid Bone
The only bone that does not articulate with another bone
Serves as a moveable base for the tongue
Figure 5.12
Slide 5.26
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32. The Vertebral Column Vertebrae separated by intervertebral discs
The spine has a normal curvature
Each vertebrae is given a name according to its location
Figure 5.14
Slide 5.28
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33. The Bony Thorax Forms a cage to protect major organs
Made-up of three parts
Sternum
Ribs
Thoracic vertebrae
Figure 5.19a
Slide 5.31a
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34. Arches of the Foot
Bones of the foot are arranged to form three strong arches
Two longitudinal
One transverse
Figure 5.26
Slide 5.42
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35. The Fetal Skull
The fetal skull is large compared to the infants total body length
Figure 5.13
Slide 5.27a
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36. The Fetal Skull
Fontanelles – fibrous membranes connecting the cranial bones
Allow the brain to grow
Convert to bone within 24 months after birth
Figure 5.13
Slide 5.27b
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37. Paranasal Sinuses
Hollow portions of bones surrounding the nasal cavity
Figure 5.10
Slide 5.25a
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38. Paranasal Sinuses Functions of paranasal sinuses Lighten the skull
Give resonance and amplification to voice
Figure 5.10
Slide 5.25b
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39. Joints Articulations of bones Functions of joints
● Hold bones together ● Allow for mobility
Ways joints are classified
Function - Movement
Immovable joints – synarthrosis (sutures)
Slightly movable joints – ampiarthrosis
Freely movable joints – diarthrosis (synovial joints)
Structure
Fibrious joints – immovable joints = synarthrosis
Cartilaginous joints –Ampiarthrosis = slightly moveable
Synovial joints – diarthrosis = freely movable

40. Fibrous Joints = synarthrosis
Bones united by fibrous tissue
Examples
Sutures
Syndesmoses
Allows more movement than sutures
Example: distal end of tibia and fibula
Figure 5.27d, e
Slide 5.46
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41. Cartilaginous Joints Bones connected by cartilage
Examples of Synarthrosis
Epiphyseal plate
Verterbrae between ribs & sternum
Examples of ampiarthrosis
Pubic symphysis
Intervertebral joints
Figure 5.27b, c
Slide 5.47

42. Synovial Joints General structure:
Articular cartilage – acts as a lubricant
joint cavity filled w/Synovial fluid
Articular capsule – fibrious CT
Reinforcement ligament
Figure 5.27f–h
Slide 5.48

43. Types of Synovial Joints Based on Shape
1. non-axial joints – found/located where bones are flat or
slightly curved; allowed for only slipping movements
betweeen bones (joints of wrist)

44. Types of Synovial Joints Based on Shape
2. uniaxial joints – movement of bone in only 1 plane
Ex: pivot joint, hinge joint

45. Types of Synovial Joints Based on Shape
3. biaxial joints – move in 2 planes
Ex: condyloid joints, saddle joints

46. Types of Synovial Joints Based on Shape
4. multiaxial joints – moves in all planes
Ex: ball and socket joints

47. Inflammatory Conditions Associated with Joints
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
Slide 5.53
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48. Clinical Forms of Arthritis
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
Slide 5.54a
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49. Clinical Forms of Arthritis
Gouty Arthritis
Inflammation of joints is caused by a deposition of urate crystals from the blood
Can usually be controlled with diet
Slide 5.54b
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50. Changes in the Human Skeleton
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
Slide 5.12
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51. Developmental Aspects of the Skeletal System
At birth, the skull bones are incomplete
Bones are joined by fibrous membranes – fontanelles
Fontanelles are completely replaced with bone within two years after birth
Slide 5.55
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