The Skeletal System

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. The two forms of marrow are red and yellow marrow

C. Microscopic Structure

1. Intro

a. Bone cells are called osteocytes

b. Lacunae are tiny chambers that contain osteocytes

c. Lacunae form concentric that contain osteocytes

d. Osteocytes transport nutrients and wastes to and from the nearby cells

e. Cellular process of the osteocytes pass through the canaliculi

f. The intercellular matrix of bone is composed of collagen and inorganic salts

2. Compact Bones

a. An osteon is a cylinder shape unit of compact bone

b. The substance of compact bone is formed from many asteons cemented together

c. Each central canal contains blood vessels and nerves

d. Pereforating canals connect osteons

e. Pereforating canals contain layers veseels and nerves

3. Spongy Bone

a. Spongy bone is composed of osteocytes and intercellular material.

b. Unlike compact bone, the bone cells do not aggregate around central canals.

c. Instead the cells lie within the trabeculae

d. Bone cells get canaliculi that lead to the surface of trabeculae

II