Applied Anatomy: Bones

Wolff’s Law

given that a bone appears to be naturally disposed to a given shape, this bone will increase or decrease its density according to the functional forces to which it is subjected

type of fiber found within bone

• mineralized hyaline cartilage

• non-mineralized hyaline cartilage

• collagen

structure of the long bone

1. diaphysis

2. epiphyses

3. epiphyseal plate

4. periosteum

5. medullary cavity

6. endosteum

diaphyses

• bone shaft

• more narrow

• bone is of the compact variety

epiphyses

• two ends to the long bone

• larger than the diaphyses

• bone is of the cancellous variety

epiphyseal plate

• separates epiphyses from diaphyses

• the location of longitudinal bone growth

• center of plate is filled with hyaline cartilage

periosteum

• covering of the bone

• on its inner surface, you find osteoblasts and osteoclasts

medullary cavity

• cavity that lies int eh center of the bone

• cavity is arranged parallel to the long axis of the bone

• the area in which bone marrow is housed (plays a vital role in formation of red blood cells)

endosteum

• lines the border of the medullar cavity and the bone

• superficial aspect (where it connects to the diaphyses) contains both osteoblasts and osteoclasts

bone textures

• compact bone

• cancellous bone

compact bone

• bone is very dense

• able to withstand greater quantities of force

• diaphysis has compact bone

structure of compact bone

• osteon

• lamella

• lacunae

• collagen

• haversian canals

• volkmann’s canals

cancellous bone

• bone is not very dense, almost spongy

• nit very able to withstand forces

• areas that contain a good deal of cancellous bone will be larger in size than areas containing a good deal of compact bone

• epiphyses has cancellous bone

osteon

• structural unit of compact bone

• arranged parallel to the long axis of the bone

• look like little pillars that are perfect to resist compressive forces that act on bone

  • look like rings similar to rings of a tree

lamella

• structures within the osteon that appear to be the ‘growth rings’

• within each osteon there are numerous lamella

• circular in shape and arranged one inside the next

• compact bone is sometimes called lamellar bone because of lamella

lacunae

• at the junction of the lamella

• little ‘holes’ in which you will fine osteocytes

collagen

• on the outside of each osteon is an arrangement of collagen fibers

  • arranged in an oblique fashion

• these collagen fibers in each congruent osteon run in opposite directions

• provide the primary mechanism by which rotational forces about the longitudinal axis are resisted

haversian canals

• central to each osteon

• canal that house blood vessels and nerves

• arranged paralled to the longitudinal axis of the bone

volkmann’s canals

• connect the haversian canals together

• a series of perpendicular canals