The Skeletal System

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Chapter 7

I.Bone Structure
A. Bone Classification
1. 4 Classes – Long, Short, flat and irregular
2. Example of a long bone- forearm and thigh bones.
3. Short Bones are shaped like cubes
4. Ex. Of short bones are in wrists and ankle bones
5. Flat bones are platelike structures
6. Ex of Flat bones are platelike structures
7. Irregular bones vary in size
8. Irregular bones vary in size
9. Examples of irregular bones are those of the vertebra and some facial bones
10. Round bones are also called sesamoid bones
i. They are small and modular and embedded in tendons ii. Example is the patella (kneecap)
B. Parts of a long bone
1. An expanded end of a long bone is an epiphysis
2. An epiphysis articulates with another bone
3. Articular Cartilage is located on the epiphysis
4. The shaft of a long bone is called a diaphysis
5. Periosteum functions t form and repair bone tissue
6. Periosteum is a tough, vascular, fibrous membrane covering the diaphysis of a bone
7. Processes provide sites for attachment of tendons or ligaments
8. The wall of the diaphysis is composed of compact bone
9. Compact bone has no gaps
10. Ephiphysis is composed of spongy bone
11. Spongy bone consists of bony plates called trabeculae
12. A bone is composed of spongy and compact bone
13. A canal called the medullary cavity runs through the diaphysis
14. The endosteum lines this cavity and spaces of the spongy bone
15. Endosteum contains bone forming cells
16. The tissue that fills the spaces of the bone is called marrow
17. &nb...

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...ome osteocytes
11. Periosteum comes from cells of the primitive conncective tissue that persist outside of the developing bone.
12. Compact bone is formed by osteoblasts on the inside of periosteum
13. Intramembranous ossification is the process if replacing connective tissue to form an intramembranous bone.
D. Endochondral Bones
1. Most of the bones are these types of bone
2. They develop as masses of hyaline cartilage
3. Eventually the cartilage decompses forming periosteum from connective tissue that encircles that developing structure
4. Blood vessels and undifferentiated connective tissue cells invade the disintegrating tissue
5. Some of these cells become osteoblasts
6. Ostoeblasts form the spongy bone in the spaces previously housed by cartilage
7. Endochondral ossification is the process of forming an endochondral bone by the replacement of hyaline cartilage.
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