1. The Skeletal System

2. FYE: Your Bones…  Bones aren’t just pieces of your skeleton
 They are a connective tissue impregnated with minerals!
 Bones aren’t dead!
 They have cells, bloody supply & nerves (feelings!)
 Bones are strong!
 Standing still the force on hip = 3x bodyweight (muscle pull) & a running man exerts a dead wt force of ~590 lbs!

3. The Skeletal System Some Vocab… Parts of the skeletal system
BONE = Osseous Tissue
Osteology = Study of bones
Arthrology = Study of joints
Kinesiology = Study of movement
Parts of the skeletal system
Bones
Ligaments (connect bone to bone)
Cartilage
Tendons (connect muscle to bone)

4. Functions of the Skeletal System
Support
For wt of entire body
Framework for muscle attachment
Protects internal organs
Storage
Calcium & Phosphate
Fat cells (in yellow marrow!)
Produces blood= Hematopoiesis
Red marrow makes cells
 3 million new each second!
Found in: pelvis, ribs, clavicle, vertebra, skull, ends of long bones

5. Bone Classification: Shapes
Sternum, scapula, ribs
Clavicle, patella
Femur, Phalanges & metacarpals
Tarsals
Figure 6-1

6. An Overview of the Skeleton

7. An Overview of the Skeleton
Axial Division
Forms center axis for everything to attach to
Includes: 80 bones
Ribs, Sternum, Vertebra (including sacrum) & Skull (including the hyoid)
Appendicular Division
Includes: 126 bones
Upper & lower extremities, Pelvis & Shoulder (clavicles & scapula)

8. An Overview of the Skeleton
Skeletons differ in shape based on what?
Why is looking at bones important/useful?

9. An Overview of the Skeleton
How are male & female skeletons different?
Skull:
Frontal bone
Cranium
Mandible
Pelvis:
Pelvic outlet
Pubic angle

10. An Overview of the Skeleton
The Vertebral Column
Cervical: (7)
C1 = Atlas – holds head up attaches to skull (nod)
C2 = Axis – pivots (no)
C7 = Vertebral prominens – prominent landmark
Thoracic: (12)
Each joins with a rib
Lumbar: (5)
Holds wt of body, takes most stress = biggest!
Sacrum: (1) (5 fused together)
Supports & strengthens pelvis/hips
Coccyx: (1) (4 fused together)

11. Bone Anatomy

12. Bone Tissue  Two types: Compact & Spongy Compact Bone
Layers of compact cover all bone surfaces, except at joints
Found where stresses occur

13. Bone Tissue Spongy Bone Network of bony rods (trabeculae)
Found in center & in epiphysis
Lighter to decrease
wt of skeleton
Spaces filled with
marrow

14. BONE CELLS 1. Osteocytes 2. Osteoblasts  3. Osteoclasts 
Mature bone cells in compact bone
2. Osteoblasts 
Cells that make new bone (osteogenesis)
3. Osteoclasts 
Bone eaters - secrete acid that dissolves matrix (osteolysis) to release stored minerals
 = Found in Endosteum & Periosteum

15. Bone Formation and Growth
Begins ~6wks after fertilization - embryo is ~12mm long
Continues until yrs
Epiphyseal Plates(discs) in ends of long bone become solid lines when done growing!

16. Bone Growth
Figure 6-6

17. Bone Remodeling/Homeostasis
Remodeling - Continuous breakdown and reforming of bone tissue - 18% turned over/year
FYE: your oldest bones are ~7 yrs!
enables skeleton to adapt to new stresses
FYE: Cast on leg for 6 wks - leg loses 1/3 bone mass!
inactivity = degeneration
needed for Ca regulation - bones store 2-4 lbs
Osteoclasts break down worn-out bone cells & put
Ca in blood as needed
FYE: Continues until late 40’s then bone start to get old too!
Osteoblasts pull Ca out of blood & build new

18. Disorders in Bone Growth & Remodeling
Osteoporosis = bone mass reduced, can happen at any age
inactivity
low Ca
age (males - lose 3%/decade starting in 30’s,
females lose 8%)

19. Disorders in Bone Growth & Remodeling
Osteomalacia (Rickets) = Soft Bones from lack of Vit.D causes low Ca

20. Disorders in Bone Growth & Remodeling
Osteogenesis Imperfecta = Genetic disorder affecting collagen fiber formation (1 in 20,000)

21. Disorders in Bone Growth & Remodeling
Achondroplasia (Dwarfism) = Genetic disorder affecting cartilage formation mainly at epiphyses

22. Disorders in Bone Growth & Remodeling
Acromegaly (Giantism) = Excess growth hormone - most often after epiphyseal plates closed

23. Disorders in Bone Growth & Remodeling
Marfan’s Syndrome = Defective CT - excess cartilage at epiphyseal plates

24. The Axial Division: The Skull
Figure 6-10

25. The Axial Division: The Skull
Figure 6-11(a)

26. The Axial Division: The Skull
Figure 6-11(b)