Skeletal System

Bone Functions

˜Attachment for muscles

˜Mechanical basis for movement (works as levers; bones along with the adjacent joints form levers which permit movement

˜Protection of internal organs

˜Support frame for body

˜Storage for calcium, phosphorous, and other salts

˜Production of red and white blood cells

How many bones are in the body?

206 bones

How many bones are in the axial skeleton?

80

How many bones are in the appendicular skeleton?

126

What is the axial skeleton?

Protects the head and trunk

What are some parts of the axial skeleton?

skull, vertebrae, sternum, and ribs

What is the appendicular skeleton?

Provides mean for movement

What are some parts of the Appendicular skeleton?

upper limbs, lower limbs, pelvic girdle, and shoulder girdle

What is the Periosteum?

Tough fibrous tissue that covers the bone except the articular ends.

Blood vessels and nerves exit and enter through the periosteum.

What is Compact (Cortical) Bone

• Underneath the periosteum

• Strong, dense layer of the bone which gives its strength

What is the Spongy (Cancellous) Bone?

• Inner, less dense, porous layer.

• Contains trabeculae and osteoblasts.

• Found in the articular ends

What are osteoBlasts?

bone forming cells

What are osteoClasts?

bone destroying cells

What is inside trabeculae?

Red and Yellow bone marrow

What does red bone marrow produce?

red and white blood cells

What does yellow bone marrow store?

Adipose (fat) cells

What is the medullary cavity?

The central cavity along the long bone

What does the medullary cavity contain?

trabeculae filled with yellow bone marrow

Where is red bone marrow found in long bones?

At the ends of the bone

What is the endosteum?

it lines the medullary cavity

What is Hyaline Cartilage?

clear cartilage or connecting tissue over articulating surfaces

Where is the Nutrient Foramen located?

near the center of long bones and passes though the medullary cavity

Where do the nutrients go in the nutrient foramen?

goes into the spongy bone and marrow

Where do the periosteal arteries enter and supply?

enter at different points to supply the compact bone

Where do the epiphyseal arteries enter?

at the end of the bones

What is ossification?

Development and formation of bones

In which month does ossification start in the embryonic life?

2nd month

What are the 2 types of processes in ossification?

Intermembranous and Endochondral

What type of bone is formed by intramembranous?

Flat bones

Where are flat bones developed?

In the embryo

Which ossification process develops sutures?

Intramembranous ossification

What are some examples of bones developed through the intramembranous ossification?

sternum, skull, and mandible

When are sutures formed?

After birth

Where does endochondral ossification develop?

Hyaline cartilage in the embryo

Endochondral Oss. occurs from 2 distinct centers of development

• primary

• secondary

When does Primary Oss. begin?

before birth

What does primary oss. form?

long central shaft in long bones (diaphysis)

What kind of bones does primary oss. form

short and irregular

When does Secondary Oss. begin

After Birth

What happens in secondary oss.?

separate bones begins to develop at both ends of the long bone

What are the ends of long bones called?

Epiphyses

What is the Epiphyseal Plate?

It is a growth plate btwn the epiphysis and the long bone. Made out of cartilage.

At what age is bone development usually completed by?

25 yod