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?

206How 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. Support2. Protection3. Movement4. Mineral storage5. Hematopoiesis (blood cell

formation)

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

Classification of BonesBones are identified by:

1. ShapeA. Long bonesB. Short bonesC. Flat bonesD. Irregular bones

2. Internal osseous tissuesA. Compact – dense and heavy; makes up hard outer surfaces of bones B. Spongy – very porous; typically surrounded by compact bone

3. Bone markings

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 skullFigure 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 Point1. 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.