general anatomy and development of bones

this ppt include general anatomy of bone , types of bone and development of bone..

1. Classification Ossification Blood supply BONES

2. Types of bone tissue Two basic types Compact bone: Dense and homogenous Forms walls of the bone Spongy bone: Slender intertwined pieces of bones enclosing a space filled with non-bone tissue Found in the interior of normal bone

3. Classification Can be classified on the basis of Skeletal location Bone shape

4. Skeletal location Axial skeleton: Forms long axis of the body Bones of skull, vertebral column Rib cage Protect support and carry other parts of the body A ppendicular skeleton: Bones of upper and lower limbs Shoulder and hip bones (girdles) Attach limbs to axial skeleton

5. Classification According to shape: Long bones Short bones Flat bones Irregular bones

6. Long bones Longer than wide Shaft (diaphysis) plus two expanded ends (epiphyses) Primarily compact bones May have large amount of spongy bone at the ends or extremities All bones of limbs except patella, wrist and ankle bones

7. Short bones Roughly cube shaped Vertical and horizontal dimensions roughly equal Primarily made up of spongy bones, covered by thin layer of compact bone Bones of wrist and ankle

8. Flat bones Thin, flattened, usually bit curved Bones of cranium, scapula, sternum Irregular bones Complicated shape Do not fit into any other category of shape Vertebrae and hip bone

9. Functions Support Protection Movement Mineral and growth factor storage Blood cell formation (hematopoiesis) Triglyceride (fat) storage Hormone production

10. Ossification Process of bone formation Also called osteogenesis Conversion of other types of connective tissues into bone Parts of skeleton are formed during the first few weeks after conception By 8 th week, skeleton pattern is formed in cartilage and connective tissue membranes and ossification begins

11. Bone development continues through out adulthood After adulthood it continues for repair of fractures and for remodeling to meet changing lifestyles

12. Cells types involved in bone formation and development Osteoblasts: Bone forming cells Osteocytes: Mature bone cells Osteoclasts : B reak down and reabsorb bone

13. Types of ossification Intramembranous Intra-cartilaginous ( endochondral ) Intramembranous: Sheet like connective tissue membranes are replaced with bony tissue Osteoblasts migrate to membranes and deposit bony matrix around themselves and become osteocytes Bones formed in this manner are called intramembranous bones Flat bones of skull and some irregular bones

14. Intracartilaginous / Endochondral Ossification Involves replacement of hyaline cartilage with bony tissue Process: Future bones first formed as hyaline cartilage Perichondrium that surrounds hyaline cartilage models becomes infiltrated with blood vessels and osteoblasts Changes into periosteum Osteoblasts form a collate of compact bone around the diaphysis Diaphysial cartilage begins to disintegrate Osteoblasts penetrate disintegrating cartilage and replace it with spongy bone Primary ossification centre is formed Osteoclasts breakdown newly formed bone to open up medullary cavity

15. Endochondral ossification conti … Developing bone increases in length as cartilage in the e piphyses continues to grow After birth Secondary ossification centre Epiphysial ossification is similar to diaphysial except spongy bone is retained instead of broken down to form medullary cavity On completion of secondary ossification hyaline cartilage is replaced by bone except At articular surface Between epiphysis and diaphysis (epiphyseal plate or growth region)

16. Bone Growth Its under the influence of growth hormone and sex hormones Bones grow in length at epiphyseal plate Cartilage next to epiphyses continues to grow by mitosis Osteoblasts move in, ossify the matrix to form bone Process continues through out the childhood and adolescent years until cartilage growth slows down n stops Epiphyseal plate completely ossifies leaving behind only thin epiphyseal line Bone stops to grow in length

17. Bone growth conti … Bone length stops in early adult hood They continue to increase in thickness/diameter throughout life(appositional growth) Balance between osteoblasts and osteoclasts activity keeps the bone from becoming excessively heavy and bulky Osteoblasts: in the periosteum form compact bone around the external bone surface Osteoclasts: at the same time breakdown the bone on the internal bone surface, around medullary cavity

18. Blood supply Typical long bone receives Nutrient artery: P asses through cortex into the medullary cavity and ramifies Diaphyses and metaphyses Periosteal vessels: S upply superficial layers of the cortex and connect with nutrient artery system Incase of obstruction of nutrient artery, periosteal vessels are capable of meeting the needs of both systems Epiphyseal vessels : R ing of arteries entering the bone along a circular band between the growth plate and joint capsule In adults they get connected with 2 other systems at the metaphyseal -epiphyseal junction Essential for skeletal growth