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

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

Functions of the Skeletal system 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: 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): 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

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.