Skeletal system lesson 1

Long bone

Have long longitudinal axis

Short bone

Have short longitudinal axis and are more cube like

Flat bone

Are thin and curved such as some of the bones of the skull

Irregular bone

Often found in groups and have a variety of shapes and sizes

Sesamoid bone

Found in ligaments

Compact bone

Called cortical bone, very dense, located along lines of force and along the axis of bone

Cancellous bone

Called spongy bone, look more like a trabeculared matrix, found in central regions of some skull bones or at ends of long bones

Osteoblast

Undergo mitosis and secrete substance that acts as framework for bone

Osteocytes

Mature osteoblast, cannot divid by mitosis and reside in lacunae

Osteoclasts

Capable of demineralizing bone, they free up calcium from bone and release it into the blood depending on the body’s needs

Flat bones- intramembraneous bones

Develop in sheet like layers during ossification bone formed sheet like layers of connective tissue and then these layers have vascular supply and contain bone forming cells called osteoblast

Tubular bones- called endochodral bones

Develop from cartilage templates, during the process bones develop from hyaline cartilage

1st step of formation

Formation of the outer covering- Periosteum

Step 2 of formation

Development of primary and secondary ossification center

Step 3 of formation

Development of medullary cavity

Step four of formation

Formation of epiphyseal plates and spongy bone