The Skeletal
System
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
How many bones does an adult body have?
206
How many bones are babies born with?
350
Largest bone?
Femur: thigh bone
Shortest Bone?
Stirrup: located in the ear
Functions of the Skeletal system
1.
2.
3.
4.
5.
Support
Protection
Movement
Mineral storage
Hematopoiesis (blood cell formation)
What’s in a bone?
• Bones, Muscles, and Joints
Classification of Bones
Bones are identified by:
1. Shape
A. Long bones
B. Short bones
C. Flat bones
D. Irregular bones
2. Internal tissues
A. Compact
B. Spongy
3. Bone markings
Compact Bone
Spongy Bone
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.
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
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
Shape: Flat Bones
• The parietal bone of the skull
Figure 6–2b
Shape: Irregular Bones
• Have complex shapes
• Examples: Vertebrae, Mandible, Sacrum,
Pelvis
Shape: Short Bones
• Are small and thick
• Cube-shaped and contain mostly spongy bone
• Examples: Carpals, Tarsals,
Calcaneus
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
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.