1. Ch. 5
SKELETAL SYSTEM

2. Chapter Objectives
Use the terminology associated with the skeletal system and …
Learn about the following:
Bone structure and types
Bone tissue & function
Bone development and growth
Understand the aging and pathology of the skeletal system

3. CSI CASE STUDY
There is a volunteer neighborhood cleanup day going on in your community. A young boy who is helping out by dragging a heavy bag of litter all of a sudden lets out a loud cry of pain. You are thinking that maybe the boy pulled a muscle. To your surprise, you notice that his hand is dangling as if he broke his forearm. You rush the child to his parents, and he is hurried off to the hospital. Later that day, you see the boy’s father, and he tells you how the boy is doing.

4. He expresses that his son should really be more careful about his activities. His son has broken both his legs twice, as well as that same arm, on the padded school playground. He then explains that it takes a long time for the boy’s bones to heal. The father mentions that two years ago the boy lost his hearing in one ear after getting too close to an exploding fire cracker. The father ends the story saying, “Otherwise, he is your typical kid. He hardly has a sick day off from school, and he is growing like a weed.”

5. Overview Humans have an endoskeleton (internal)
The skeletal system is composed of over 200 bones, cartilage, ligaments, joints, and tendons
Functions in support, movement, protection, storage & hemopoeisis.
Endoskeleton: An internal skeleton (as opposed to an exoskeleton, or external skeleton, as in an arthropod)
Bone: Hard connective tissue
Cartilage: Flexible connective tissue
Ligament: Connective tissue that joins bone to bone
Tendon: Connective tissue that joins muscle to bone
Joints: Where 2 bones meet

6. FUNCTIONS
SUPPORT: framework for all soft tissues
PROTECTION: protects underlying organs
STORAGE: stores calcium (Ca) for bone growth & maintenance
HEMOPOIESIS: new blood cells are made within red bone marrow

7. most trainers recommend  short stretching routine before & a
Stretching: The Truth
most trainers recommend  short stretching routine before & a
after any physical activity, especially high- impact activities
rationale  reduces the risk for joint injury
now being SCRUTINIZED by medical researchers.
studies show stretching may not lower the risk for injury
preworkout stretching in 1543 runners actually contributed to the # of running injuries.
47% of male runners who stretched regularly were injured
during a 1-yr period compared with 33% of male runners who did
not stretch.
Some doctors believe that stretching before doesn’t condition the
tendons for the rapid pulling and contraction of physical activity.
Researchers cannot find a reason why; however, studies show
that stretching is good after a workout  reduces tension on
tendons and bone by relaxing the pull of tightened muscles.

8. The Human Skeletal System
2 divisions
1) AXIAL skeleton 
spine, rib cage, hyoid
bone, skull

9. 2) APPENDICULAR skeleton 
upper and lower appendages or extremities (i.e. arm & leg bones)
and
bones that girdle
them to the axial
skeleton (clavicle,
scapula, pelvis)

11. Irregular, Short, or Long
Bone Types
Flat,
Irregular, Short, or Long
categorized by their shape
Long bones
Categorized by shape:
Flat – thin, flattened, often slightly curved
Irregular – unique, often complicated shape that is not geometrically describable
Short – square-like shape
Long – elongated shape

12. Irregular bones
Flat Bones
scapula

13. Surface Features of Bone
Each bone has characteristic surface features that result from its attachment to ligaments and tendons.
Crest  large ridge where muscles attach
Process  large bulge where muscles attach

14. Trochanter  large, ridged bump where ligaments and tendons attach
Foramen opening where bone, blood vessels or nerves pass
Vertebral foramen

15. The
AXIAL SKELETON

16. Cranium – 8 total bones coronal suture (1) (2) squamous suture
lamboidal suture
(1)
sagital suture
(2)

17. houses the pituitary gland
(1)
sella turcica
(turkish saddle):
houses the pituitary gland
within sphenoid bone
ethmoid bone (1)

18. Face Bones: 14 total bones (2) nasal bones (2) zygomatic arch (2)
inferior conchae (2)
maxilla (2)
vomer (1)
mental foramen (passages for nerves and vessels
mandible (1)

19. palatine (2)
foramen magnum: hole
for spinal cord

20. ONLINE MATCHING QUIZZES  Bones of the Skull

21. Ear bones: 6 total
(in temporal bone)

22. Sinuses: (frontal, maxillary, sphenoid, ethmoid sinuses)
spaces or cavities inside
some of the cranial bones
(4 pairs);
air conditioners??
make skull lighter??
crumple zones??
resonance chamber??
(frontal, maxillary,
sphenoid, ethmoid
sinuses)

23. Fontanels:
soft spots on baby’s skull
allow compression of skull during birth
fuse & form sutures (joints) before baby is 1- 2yrs old

24. Vertebral Column – 26 total bones
concave curve
convex curve
concave curve
(1)
5 separate in a child
convex curve
(1)
3-5 separate in a child

25. allows head to rotate

26. cartilage that
acts as a
cushion
spinous process
vertebral foramen:
hole spinal cord sits
spinal cord

27. Vertebral Column Function
can rotate and move forward, backward, and sideways
encloses and protects spinal cord
serves as attachment for ribs and muscles of back (thoracic vertebrae)
adult curves  provide strength & balance to support weight of body so we can stand and walk on 2 ft

28. Curvature of Spine Adult’s spine: cervical + lumbar (concave)
thoracic + sacrum (convex)
Newborn’s spine:
continuous convex curve
Head up = concave cervical
Stand up = concave lumbar

29. Vertebral Column Animation:
Spine-fusion Surgery Video:
Microdisectomy Lumbar Microdecompression Spine Surgery Video:

30. Ribs - 24 total bones (12 pairs)
attach directly
to sternum
(14)
attach to sternum
by coastal
cartilage of
7th rib
doesn’t ossify
until 40yrs of age
attachment for
stomach muscles
(6)
(4)
don’t attach to sternum

31. The APPENDICULAR SKELETON

32. Pectoral Girdle: shoulder region
sternoclavicular joint: where
sternum and
clavicle meet;
fractures are
common
glenoid cavity:
arm socket;
not very protected
(2)
(2)
where clavicle
and scapula meet

33. Shoulder Dislocation Animation: Torn Rotator Cuff Animation:
Torn Rotator Cuff Animation:

34. Arm and Hand Bones: distal middle thumb side; allows hand proximal
(2)
(28)
distal
(2)
middle
thumb side;
allows hand
to rotate
proximal
(2)
(10)
pinky side
(16)

35. H U M E R S
head of radius
RADIUS
ULNA
olecranon process:
end of ulna; funny bone

36. Pelvic Girdle: hip region
coxal
bones (2)
acetabulum:
hip socket;
well protected
pelvic inlet
(pubic bone)

37. Head of femur (2; larger shin bone) (2; smaller shin bone)
(2)
(2)
(2; larger shin bone)
(2; smaller shin bone)
(14; ankle bones)
(10)
(28)

38. Outer anklebone
Inner anklebone
Calcaneus: heel bone (2);
largest tarsal bone

39. MALE versus FEMALE SKELETONS
smaller
larger
Inlet /
Outlet
wider
narrower
Pubic Angle

40. FEMALE
MALE

42. Human Bone Charts
Anterior view
Review skeletal system.

43. Human Bone Charts
Posterior view
Review skeletal system.

44. Concept Check #1 What are the components of the skeletal system?
bone, cartilage, tendon, ligaments
2. Describe the functions of the skeletal system.
- movement - protection
support - storage
What are the two divisions of the skeletal system? Which body parts can be found in each of these divisions?
- Axial (head, vertebrae, ribs) Appendicular (extremities, pectoral girdle, and pelvic girdle

45. Concept Check #2 4. What are the purposes of bone-surface features?
- attachment points for muscles and ligaments
holes for things to pass through
5. Describe 5 regions of the vertebral column and the column’s importance.
cervical, thoracic, lumbar, sacrum, coccyx
balance, support, flexibility
6. How do the bones of the rib cage differ.
- True ribs (attach directly), false ribs (attach indirectly), floating ribs (don’t attach)  protection

46. Concept Check #3 7. Name the parts and bones of the upper extremities.
- clavicle, humerus, radius, ulna, carpals, metacarpals, phalanges
8. Name the parts and bones of the lower extremities.
Coxal bones, femur, patella, tibia, fibula, tarsals, metatarsals, phalanges
Describe the differences between male and female skeletons.
Female – smaller in general, wider inlet, outlet and pubic angle
Male – larger in general, narrower inlet, outlet and pubic angle

47. INTERNAL
& EXTERNAL
FEATURES
of BONES

48. Anatomy of Bone Primarily comprised of compact and spongy bone.
Medullary cavity  in the center of some bones; contains bone marrow.
Compact Bone – also called Cortical Bone, the rigid outer shell of the bone
Spongy Bone – also called Cancellous or Trabecular Bone, forms the ends of the long bones and the center of other bones; composed of a honeycomb-like network
Medullary (or Marrow) Cavity – The hollow center of long bones, lined with endosteum which can generate new bone cells, and filled with bone marrow to be used as a food reserve

49. Anatomy of a Long Bone Red bone marrow  produces red blood cells
growth plate; calcified or cartilage
(end)
contains spaces for red bone marrow
 contains fatty, yellow bone
marrow (food reserve for bone cells)
(shaft)
strong membrane covering diaphysis
Compact bone  rigid outer shell of bone
acts as a cushion between bones;
sometimes called hyaline cartilage
(end)

50. External Anatomy of Bone Microscopic Anatomy of Bone
ONLINE MATCHING QUIZ 
External Anatomy of Bone
ONLINE MATCHING QUIZ 
Microscopic Anatomy of Bone

51. Microscopic Anatomy of Bone
Haversian Canal: where B.V.
pass
Haversian System or Osteon: structural unit of compact bone

52. Osteon (Haversian System):
honeycomb network of
spongy bone

53. Within 1 Osteon or Haversian System
small canals that
connect osteocytes
cavities that store
osteocytes (bone cells)
calcified rings that surround Haversian canal

54. JOINTS (ARTICULATIONS)
attach bones (helping with support,
protection, movement)

56. Ex. cranial sutures 3 Types of Joints
1. Synarthrosis joints: no movement; held together by connective tissue
Ex. cranial sutures

57. btwn frontal & parietals
btwn occipital & parietals
btwn temporal & sphenoid
btwn parietals

58. 2. Amphiarthrosis joints: slight movement; held together by cartilage
ex. pubic symphysis (in females only; fused in males) and vertebrae joints

59. Diarthrosis joints: free movement; held together by a synovial capsule
Ball and socket: widest range of motion;
found in the hip & shoulder
HIP
Glenoid cavity
acetabulum
SHOULDER

60. b. Hinge: movement in 2 directions; flex and extend; found in the elbows, knees, & fingers
Flexion: bending a joint Extension: straightening
(smaller angle) a joint (larger angle)

61. c. Pivot: 1 bone rotates around another bone; found in C1 and C2 & the radius
C1 Atlas
C2 Axis

62. Saddle joint: only 1 pair exists; thumb
flexes, extends, abducts (away from
midline), adducts (towards midline), and
circumducts (circling distal end around
proximal end)

63. e. gliding joint: least movable diarthrotic joint; found in shoulders, wrists & ankle, vertebrae

64. Anatomy of a Diarthrotic Joint
secretes
synovial fluid
to reduce friction
connective tissue; fits over ends of 2 bones and becomes periosteum
 strong
cords of
connective
tissue that
connect
bone to bone
Ligaments
Joint
capsule

65. ACL Reconstruction Video: http://www.youtube.com/watch?v=q96M0jRqn7k

66. Concept Check 4:
What are the two main parts of a long bone and where are they located?
Epiphysis – top and bottom of a long bone
Diaphysis – shaft of a long bone
Name the structural unit of bone and describe
what each of the following structures do w/in
the system: haversian canal, osteocytes, canaliculi,
lacuna, lamella
Haversian System (Osteon) b) H. canal houses
B.V., Osteocytes make bone cells, Canaliculi
connect osteocytes, Lacuna store osteocytes,
Lamella calcified rings surround HC

67. Concept Check 5: Why do you think bone needs such a complex setup?
To deliver nutrients & remove wastes to & from all parts of the bone.
13. Why are joints important?
Attach bones  support, protection, movement
Name 3 main types of joints and explain how they
differ.
Synarthrosis  no movement
Amphiarthrosis  little movement
Diarthrosis  lots of movement

68. Concept Check 6: Give 1 example for each of the 3 main types of
joints and state where they are located in the body.
sutures in skull – SYN
vertebrae in back, pubis symphysis – pelvis – AMPHI
Ball-n-socket – shoulder / hinge – elbow - DI
Rate the types of diarthrotic joints from greatest to
least movement (based on how many ways they provide
movement) ball-n-socket, pivot/saddle, hinge, gliding
What are ligaments? B) What is the synovial
membrane? C) Where can they be found?
Connective tissue that connect bone to bone
Secretes synovial fluid to reduce friction btwn 2 bones
Diarthrotic joint

69. Bone Development
&
Healing

70. One way bones form in the embryo:
Bones are living organs that can remodel themselves.
develop at different rates and times as a person progresses through the developmental stages of growth.
One way bones form in the embryo:
1. endochondral ossification (in long bones)

71. Endochondral Ossification
bone formation that begins within (endo) cartilage (chondral)
 before birth: no bones; only cartilage models
after birth: calcified matrix starts to replace cartilage models with the help of…
1. Osteoblasts  cells that BUILD bone
2. osteoclasts  cells that break down (KILL)
bone & cartilage

72. Bone Remodeling (when there is low
(when there is low
Ca in the body)
(when there is excess Ca in the body)

73. Steps of Endochondral Ossification
1. Primary ossification  osteoclasts carve out a hole in center of diaphysis of cartilage model
a. B.V. grow into bone & provide nutrients for growth & maintenance
Osteoblasts enter & secrete bone tissue to replace cartilage
a. compact bone then spongy bone
b. bone elongation takes place at the epiphyseal plate

74. Importance of Epiphyseal Plate:
presence of
cartilage plate:
bone is still growing
absence of
cartilage plate
(calcified line):
growth has ceased;
bone is mature

75. Secondary ossification occurs later in development of fetus
osteoclasts enter epiphysis  blood vessels  osteoblasts convert cartilage to bone

76. Importance of Endochondral Ossification
allows bone to respond to stress/injury by changing size, shape and density
stress on bone the rate bone is deposited
reason athletes have denser and stronger bones than less active people.

77. rigid calcified matrix
Cartilage
Bone
flexible gel matirx
more space then cells
chondrocytes (living cartilage cells)
NO blood vessels; nutrients diffuse slowly into cells slow to repair itself
rigid calcified matrix
more cells than space
osteocytes (living bone cells)
has blood vessels; nutrients diffuse quickly into cells  fast to repair itself

78. bone growth needed for bone repair
Bone Damage
bone growth needed for bone repair
bone fractures  most common type of bone damage; bone crack or splinter from
physical injury
i.e. stress fractures
Compound Fractures

79. NUTRITION IS EXTREMELY IMPORTANT!!
Bone Healing
1. Reactive phase: within hrs or a few days
a. white blood cells (WBC) and new blood vessels enter injured area to digest & carry away damaged tissue and clotted blood
2. Reparative phase (weeks to months):
WBC secrete cartilage into damaged area
osteoblasts secrete new bone tissue
3. Restorative phase:
a. osteoblasts & osteoclasts remodel bone
NUTRITION IS EXTREMELY IMPORTANT!!

81. Concept Check 7 19. How do osteoblasts and osteoclasts differ?
18. How does a babies endoskeleton differ from an adults?
19. How do osteoblasts and osteoclasts differ?
What does Ca have to do with bone
remodeling?

82. Concept Check 8
21. How are osteoclasts, blood vessels, and osteoblasts involved in Endochondral Ossification?
22. What is the importance of endochondroal ossification?
Name at least three differences between cartilage
and bone.

83. Concept Check 9 How do simple and compound fractures differ?
Briefly describe what happens in each of the 3 phases
of bone healing.

84. PATHOLOGY of the SKELETAL SYSTEM

85. Wellness and Illness over the Life Span
Most common bone and joint pathologies are related to atypical stress and strain.
Other organ-system diseases cause inflammation of bones and joints.
During a person’s lifetime, bone is constantly degraded and replaced.
Stress/strain: shin splint, stress fracture, arthritis
Inflammation: gout, lupus, fibromyalgia
Degenerative: Osteoporosis, tooth decay, myeloma and other cancers

86. Osteoarthritis – deterioration of articular cartilage; pain &
1. Shin splint – develops medial side of tibia; caused by overuse / high-impact of ankle joint
Osteoarthritis – deterioration
of articular cartilage; pain &
loss of movement
Osteoarthritis Animation:

87. Rheumatoid Arthritis Animation:
Rheumatoid arthritis – immune system
attacks connective tissue of
a joint
Rheumatoid Arthritis Animation:
Gout – metabolic disorder;
causes body to produce
oxalic acid (waste product); forms crystals
cause inflammation in
joints

88. 5. osteoporosis - excessive loss of calcified matrix causes bone degeneration
a. weak bones lead to an increase in
fractures & spine curvature
b. most frequent in elderly, white,
females; white and black males are
susceptible; very rare in black women
c. treatments: sex therapy and dietary
supplements (Ca and Vit. D)

89. Osteoporosis

90. Aging of the Skeletal System
deterioration of articular surfaces (joints); not repairable naturally (most common)
bacterial infections over time  joint decay
osteoclasts outpace osteoblasts as you age
decline in sex hormones which are needed for bone maintenance
poor nutrition or individual genetic factors

91. Concept Check 10:
27. Name and describe3 different skeletal system disorders.
28. What are the different types of arthritis?
29. Describe the possible causes of osteoporosis.

92. CSI – Conclusion
while dragging a bag of litter a young boy breaks his forearm and is hurried off to the hospital
you find out from the father that the son has already broken both his legs twice, as well as that same arm, on the padded school playground.
apparently the boy’s bones take a long time to heal and he is deaf in one ear from standing too close to an exploding fire cracker
Answer the following:
What congenital condition is causing this boy’s bones to break at such an early age?
What causes this condition?
Why do 50% of the people with this condition develop hearing loss?
What can be done to protect this boy from this condition?