Axial Skeleton Flashcards
6 Functions of Skeletal System
- support
- protection
- lever for muscle action
- hematopoiesis
- fat storage
- mineral storage
What are the 2 types of bone development?
- intramembranous ossification
- endochondral ossification
5 Steps of Intramembranous Ossification:
- mesenchyme cells become osteoblasts
- produce uncalcified osteoid tissue (collagen & ground substance)
- ECM calcifies & forms trabeculae
- trabeculae form latticework (spongy bone)
- compact bone deposited on periphery
Intramembranous ossification definition:
bone from mesenchyme tissue - no cartilage framework forming (brain & patella)
Spongy bone (with red bone marrow)
epiphyseal line
proximal epiphysis
compact bone
medullary cavity (with yellow bone marrow)
endosteum
periosteum
articular cartilage
distal epiphysis
metaphysis
diaphysis
metaphysis
Endochondral ossification definition
bone from hyaline cartilage framework (long bones)
5 Steps of Endochondral Ossification
- form hyaline cartilage model
- osteoblast develop from perichondrium (osteoblasts from mesenchyme)
- osteoblasts form bone collar (in middle)
- primary ossification in diaphysis
- secondary ossification of epiphysis
- primary and secondary center unite in an adult
5 Steps of Endochondral Ossification
- form hyaline cartilage model
- osteoblast develop from perichondrium (osteoblasts from mesenchyme)
- osteoblasts form bone collar (in middle)
- primary ossification in diaphysis
- secondary ossification of epiphysis
Are the epiphyseal plates still there in adulthood?
- yes, remain until adulthood
- primary & secondary centers unite in adult
- bones lengthen at epiphyseal plates
- plates ossify at adulthood
- epiphyseal line remains
What are the 2 directions of bone growth?
- growth in length (interstitial growth)
- growth in width (appositional growth)
What are the layers of the epiphyseal plate?
- resting hyaline cartilage
- chondrocyte mitosis
- chondrocyte hypertrophy
- ossification at diaphysis
(add cartilage, add bone, etc. - like a stack of coins)
What direction does bone lengthen?
upward
Where does appositional growth occur?
under the periosteum
How does appositional growth occur?
- add bone to periosteum side with osteoblasts and absorb bone on medullary cavity with osteoclasts
1. bone deposited with osteoblasts (add outside)
2. older bone reabsorbed by osteoclasts (take away inside)
How often is bone replaced?
- spongy bone replaced 3-4 years
- compact every 10 years
- gradually not all at once
What cells do replacement and remodeling of bone?
osteoclasts break down old bone and osteoblasts add new bone
What are Branchial Arches?
pharangyeal gill slits are surrounding by branchial arches - precursor of the jaw is the first branchial arch
Do lampreys have a jaw?
No - use a rasping movement
What is the branchial arch modification of condricthes (sharks)?
- first arch - jaw (upper jaw:palatoquadrate - lower jaw:mandible/Meckel’s cartilage)
- second arch - hyomandible (what jaw swings on)