1. The Skeletal System

2. Fun Facts A giraffe has the same # of bones in the neck as humans do
Bones are 14% of your body weight
Bone is 5x as strong as steel
Most women and girls have smaller and lighter skeletons than men and boys
The female pelvis is wider than males
Male’s growth plates harden at years of age
Female’s growth plates harden at years of age

3. How many bones does an adult body have?
206
How many bones are babies born with?
350

4. Stirrup: located in the ear
Largest bone?
Femur: thigh bone
Shortest Bone?
Stirrup: located in the ear

5. Functions of the Skeletal system
Support
Protection
Movement
Mineral storage
Hematopoiesis (blood cell formation)

6. What’s in a bone?
Bones, Muscles, and Joints

7. Classification of Bones
Bones are identified by:
Shape
A. Long bones
B. Short bones
C. Flat bones
D. Irregular bones
2. Internal tissues
A. Compact
B. Spongy
3. Bone markings

8. Compact Bone
Spongy Bone

10. Shape: Long Bones Are typically longer then they are wide
As a rule they have a shaft with heads at both ends
Mostly compact bone
All of the limbs (femur, tibia, humerus), except the wrist and ankle bones.

11. Shape: Long Bones Diaphysis (long part): Epiphysis (ends): Metaphysis:
Covered by periosteum
Sharpey’s Fibers secure the periosteum to the underlying bone
Epiphysis (ends):
Articulate with other bones
Covered by Articular cartilage
Metaphysis:
Location where diaphysis and epiphysis meet

12. Shape: Flat Bones Are thin, flattened and usually curved
Have two thin layers of compact bone sandwiching a layer of spongy bone between them
Found in the skull, sternum, ribs, and scapula

13. Shape: Flat Bones
The parietal bone of the skull
Figure 6–2b

14. Shape: Irregular Bones
Have complex shapes
Examples: Vertebrae, Mandible, Sacrum, Pelvis

15. Shape: Short Bones Are small and thick
Cube-shaped and contain mostly spongy bone
Examples: Carpals, Tarsals,
Calcaneus

16. Shape: Sesamoid (ses’ah-moyd) Bones
Special type of short bone
Form within tendons
Best known example is the patella
Develop inside tendons near joints of
knees, hands, and feet

17. Check Point
1. Approximately how many bones are there in the human body?
2. What is hematopoiesis?
3. What are the five functions of the bones?
4. What is the difference between compact bone and spongy bone?
5. Draw and diagram a long bone.