Basic Bones Flashcards
What are accessory bones?
Bones present in ancestral form
Can be mistaken for fractures
Bone not normally present in body, but present in some members of the population
What is achondroplasia?
Dominant mutant allele
Chondrocytes in metaphysis fail to multiply and enlarge
Long bones fail to enlarge, other bones unaffected
What is the axial skeleton?
Skull, vertebrae, ribs, sternum
What is the appendicular skeleton?
Limbs, limb girdles
What is cancellous bone?
‘Spongy’ bone within cortical shell
Supports bone marrow
What is cortical bone?
Hard layer of bone surrounding cancellous bone
Synonymous with compact bone
What is the diaphysis?
Forms the shaft of long bones
What is the endosteum?
Lines medullary cavities in long bones
Osteogenic
What is the epiphysial growth plate?
Interface between epiphysis and metaphysis
Cartilage made at epiphysial growth plate ossified at metaphysis
When fully developed, only articular cartilage remains
What is the epiphysis?
Forms the distal and proximal ends of bones
Can be pressure, traction epiphysis
Pressure epiphysis
Region of a long bone that forms articular surface
Traction epiphysis
Region of a long bone where tendon, ligament attaches
Elastic cartilage
Flexible, can be bent without damage
In epiglottis, pinnae
Fibrous cartilage
Can be compressed
Between vertebrae
Hyaline cartilage
On articular surface of bones
Forms precursor to skeletal system
What is a long bone?
Bone with a shaft, proximal and distal ends
Medullary cavity
Cavity within bones.
Contains bone marrow - can be yellow or red
Metaphysis
Part of diaphysis
Adjacent to epiphysis
At each end of a growing bone
Site of remodelling, high metabolic activity
Nutrient artery
Delivers nutrients, bone cells to cartilage model
Initiates ossification at primary site
Inserts into the nutrient foramen
Location of nutrient foramen
Cartilage skeleton, developing bones
Normally in the middle of developing bone
Osteoblasts
Cells that produce bone
Osteoclasts
Cells that break down, remodel bone
Pneumatic bones
Hollowed bones
Reduce weight of what would otherwise be a heavy bone
EG: sinuses in skull
Periosteum
Lines exterior of cotrical bone
Very vascularised, innervated
Outer fibrous layer
Inner osteogenic layer
Sesamoid bones
Lie within a tendon
Sesame-seed shaped
Trabecular bone
Synonymous with cancellous bone
Good at resisting static force
Standard structure of a bone 1) 2) 3) 4)
1) Cancellous bone surrounded by cortical bone
2) Bone marrow is within medullary cavity of cancellous bone
3) Cortical bone surrounded by periosteum exteriorly, endosteum interiorly.
4) Periorsteum and endosteum are osteogenic
Two broad types of ossification
Intermembranous ossification
Endochondral ossification
Example of intermembranous ossification
Skull formation
Skull formation 1) 2) 3) 4)
1) Skull initially 1 cell thick
2) Cortical bone forms
3) Cancellous bone forms in between
4) Anterior fontanelle closes ~ 18 months
Fontanelle
Area of skull not fully developed, to allow foetal skull to change shape in birth canal
Endochondral ossification
1)
2)
1) Hyaline cartilage precursor to skeletal system
2) Bone first appears ~6-8 weeks of life
Primary centre
Where bone first appears
Where does bone first appear when developing?
In middle of shaft.
Extends from middle to extremeties
How does ossification begin?
Blood vessels induce osteoprogenitor cells (mesoderm) to become osteoblasts
When do the periosteal and endosteal layers form?
Simultaneously
How do the diaphysis, epiphysis and metaphysis form bones?
Diaphysis forms shaft of bone
Epiphysis forms ends of bone
Metaphysis ossifies chondrocytes fed through it by the epiphysial growth plate
What are secondary epiphysial centres?
Signify that growth is still occurring
Can be confused with a fracture
If damaged, can prevent growth
Blood supply to developing bones 1) 2) 3) 4)
1) Nutrient
2) Periosteal (to exterior of shaft)
3) Metaphysial
4) Ephiphysial
When does bone first appear?
First 6-8 weeks of life
