The Skeletal System

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 18-21 years of age • Female’s growth plates harden at 16-18 years of age

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

4. 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 osseous tissues A. Compact – dense and heavy; makes up hard outer surfaces of bones B. Spongy – very porous; typically surrounded by compact bone 3. Bone markings

8. 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.

9. Shape: Long Bones Diaphysis (long part): • 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

10. 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

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

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

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

14. 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

15. 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.