Intro to bones and soft tissue Flashcards
What are the 2 types of skeleton
axial and appendicular skeleton
What is in the axial skeleton
skull, spine and rib cage
How many bones in adults
206 + sesamoid
how many bones in children
270
What are 5 function of the skeleton
1) movement
2) protection
3) support
4) mineral storage
5) produces blood cells
What is the primary bone formation method after the 1st 2 months of fetal development in utero
endochondral ossification
What is endochondral ossification
A way of bone formation
What is the blueprint for ossificaiton
hyaline cartilage
What is the first stage of endochondral ossification
1) Perichondrium is vascularized (blood vessels penetrate it)
What do these blood vessels that penetrate the peridchondrium do
Stimulate mesenchymal cells to differentiate into osteoblasts
Where is the primary ossification centre
centre of long bone
Where is the secondary ossification centre
at the end of the bone
What is the junction between the primary and secondary ossification centres called
epiphysial plate
Where does the growth of bones occur
at epiphysial plate
What are the 4 types of bone cells
1)osteogenic - bone ‘stem cells’ and so in deeper layers of periosteum
2) osteoblasts - secretes osteoid, bone building/forming and mineralisation of osteoid
3) osteoclasts - ‘bone breaking to release Calcium’, dissolve and resorb bone by phagocytosis and derived from bone marrow
4) osteocyte - ‘mature’ bone cell
when an osteoblast becomes embedded in its secretions
senses mechanical stress to direct osteoblast and osteoclast activity
What do osteogenic cells do
bone stem cells and are in deeper layers of periosteum
What do osteoblasts do
‘bone building’ -secretes osteoid and mineralisation of osteoid
What do osteoclasts do
‘bone breaking’
phagocytoses and resorbs bone by phagocytosis and derived from bone marrow
What are osteocytes
‘mature bone cells’ - when an osteoblast becomes embedded in its secretions
Can detect mechanical stress and so directs osteoblast and osteocyte activity
Where in the bone are osteogenic cells (THINK!)
in the deep layers of the periosteum
Where are osteoblasts
‘builds’ so is in the growing sites of the bone including periosteum and endosteum
Where are osteocytes
in entrapped layers of bone
Where are osteoclasts
at injured or unneeded areas of the bone
Describe the organisation of the bone matrix
Organic component (40%) of which: Type 1 collagen (90%) ground substance ( 10%) which is made up of proteoglycans, glycoproteins and cytokines and growth factors Inorganic component 60% of which: Calcium hypoxyapatite osteocalcium phosphate
What is immature bone
Bone that is ‘woven’ and not yet mineralised
First bone that is produced
What is a cancellous bone and where are they found IN THE SKULL bone
They are ‘honeycomb’ like structures that are spongy
- NOT good for weight bearing
- in between the cortical bone
- is TRABECULAR
- is light but not
What is a cortical bone
good for weight baring
is compact and dense
‘shell’ on the outside
Are osteons present in both cortical and cancellous bones or one or the other and what are they
osteons - repeating structural units which have concentric lamellae that surround a central Haverian canal
EXIST in cortical bone only
What does the haversian cannal consist of
blood vessels, lymph and nerves
Which cells make up the lamellae
- laid down by osteoblasts but as they get drapped within their own mineral matrix they became osteocytes
what are lacunae
Small spaces for osteocytes in them
What are canniculli
radiate from lacunae filled with extracellular fluid
What are volkmans canals
transverse radiating canals
Describe the structure of a long bone from the joint to the diaphesis
Epiphesis
Phesis (part that grows as a child )
Metaphysis
Diaphysis (through - dia)
What are the 2 major ways of bone growth
1) interstitial growth of the long bone (lenghtens )
2) appositional growth (thickens )
Where does interstital growth of bones happen
At the physis (physeal plate )
How does interstitial growth happen
At the epiphyseal side:
cells in the reserve zone migrate to the proliferative zone and undergo mitosis
They then undergo maturation and hypertrophy (accumulation of lipids, glycogen and alkaline phosphatases )
Then matrix calcifies and cell death happens
Where happens at the epiphyseal side of interstitial growth
hyaline cartilage activates and divides to form hyaline cartilage matrix
What happens at the diaphyseal side of interstitial growth
hyaline cartilage is calcified and dies and is replaced by bone
Describe how appositional growth happens
1) Blood vessels form along the ridges of the periosteal groove
2) Periosteal ridges fuse, forming an endosteal lined tunnell
3) osteoblasts in endosteum form new lamellae inwards to the centre of endosteum forming new osteons
4) Bone grows outwards as osteoblasts form new conecntric lamellae. Periosteal ridges fold as new osteons are formed
What are the 3 subsets of fibrous joints
1) sutures (coronoid suture )
2) syndesmosis ( tibia and fibula or radius and ulna)
3) interosseus membrane ( as above)
What are cartilogenous joints and give an example of it
bones joined by cartilage (eg vertebra )
Give the 6 types of synovial joints
1) hinge
2) ball and socket
3) saddle
4) plane
5) pivot
6) condyloid
What type of joint is the hip joint
ball and socket (multi axial spheroidal joint)
What type of joints are in the ankle or elbow
hinge joint ( uniaxial as can only rotate in 1 plane)
What type of joint is the knee joint
hinge joint sort of…. a modified hinge joint
Why is the knee not a cartilogenous joint
cartilage in knee is incomplete so is is a SINOVIAL JOINT
What does the synovial membrane do
secretes synovial fluid to reduce friction
What else stabilises joints
1) ligaments
2) tendons
3) bone surface congruity
What is the function of ligaments
to prevent excessive movement that could damage joints
What do more ligaments and tighter ligaments do
more stability but less mobility
What could less stability potentially lead to
risk of dislocation
