Intro To Bone Flashcards
Mechanical properties of bones
Cable like flexibility and pillar like stiffness
What are bones resistant to
Compression and tension
What feature gives bones resistance to tension
Framework consists of collagen and other bone proteins
What gives bones resistance to compression
Impregnation of collagen with crystalline mineral
What is crystalline mineral impregnating collagen
Hydroxyapatite
2 main types of bone tissue
Woven
Lamellar
When can woven bone be seen in adults
Repairing fractures
Anatomical breakdown of a long bone
Proximal epiphysis Metaphysis Diaphysis Metaphysis Distal epiphysis
Describe arrangement of lamellar bone
Outer layer is compact lamellar bone then inner layer consists of interlacing struts of cancellous bone
Other names for cancellous bone
Spongy and trabecular
Outermost layer to bone
Periosteum
Layers to periosteum
Cellular and fibrous
Functions of periosteum
Bone repair and growth
Vascular
Good sensory nerve supply
Order of development to bone cells
Osteogenic cell-> osteoblast -> osteocyte
When does the skeleton start to form
6 weeks into fetal life
Name of bone development
Ossification
2 types of ossification
Intramembranous
Endochondral
Where does intramembranous ossification occur
Existing vascular connective tissue
Where does endochondral ossification occur
Existing fetal cartilage models
Process of intramembranous ossification
Bone matrix deposited around collagen which mineralises to form woven bone
This woven bone remodels to form lamellar bone
Process of endochondral ossification
Cartilage calcifies so chondrocytes die. Periosteal osteoclasts cut channels for sprouting vessels. Osteoblasts enters with vessels to build bone around them
Other name for bone matrix
Ostein
Problem faced with bone development
When bones are growing they have to support large weights which affect growth at bone terminals
Solution to issue of growing bone having to support weights
Shaft ossified from cartilage first then terminals. This growth continues by ossification at growing cartilage plate at metaphysis between them. This ceases once the plate is over run by ossification
Age related changes in appearances of bones.
In child’s bones the epiphyses ossify roughly at 24 months but epiphyseal plate remain cartilaginous until after puberty
Can bones adapt other than in fractures
Able to grow and adapt its bulk, density and internal and external structure in response to pattern of use
What is key to bone growth and repair
It’s large blood supply
How does bone grow in diameter
Osteoblasts and osteoclasts create grooves in bone surface whilst expanding then new blood vessels align in them. Osteoblasts build new osteons around vessels
How is bleeding important in fracture healing
Haematoma becomes infiltrated by fibrous matrix and invaded by bone progenitors
