Bones and Soft tissue Intro Flashcards
What composes the Appendicular Skeleton?
Pectoral girdle, Upper and lower limbs, pelvic girdle
What composes the Axial skeleton?
Cranium, vertebral column, rib cage
What are the functions of the skeleton?
Support
Protection
Movement
Mineral storage
Produces blood cells
How do bones develop in utero?
Flat bones are formed through intramembranous ossification ( mesenchymal cells –> bone ) as well as mandible, clavicle
Long bones are formed by endochondral ossification
( mesenchymal cells –> cartilage –> bone )
Ossification:
(a) of mesenchymal cells then differentiate into (b) and ossification centre forms.
Secreted (c) traps osteoblasts which become osteocytes
(d) and (e) form
Compact bone develops superficial to (f) bone. Crowded blood vessels condense into red bone marrow.
a - Condensation b - Osteoblasts c - osteoid d - trabecular matrix e - periosteum form f - cancellous
Intramembranous Ossification:
(a) of mesenchymal cells then differentiate into (b) and ossification centre forms.
Secreted (c) traps osteoblasts which become osteocytes
(d) and (e) form
Compact bone develops superficial to (f) bone. Crowded blood vessels condense into red bone marrow.
a - Condensation b - Osteoblasts c - osteoid d - trabecular matrix e - periosteum form f - cancellous
Endochondral Ossification:
(a) forms a ring of perichondria around itself as a cartilage matrix. This becomes (b) forming the (c) containing an artery.
At the end of the long bone a (d) forms.
a - Hyaline cartilage
b - Calcified
c - Primary Ossification centre
d - Secondary Ossification centre
What are the 5 stages of Endochondral Ossification?
Bone collar formation
Cavitation
Periosteal Bud invasion
Diaphysis Elongation
Epiphyseal Ossification
What is the Epiphyseal plate?
Junction between primary and secondary ossification centres
It is where the growth of bones happens after birth
What is a Osteogenic cell?
Bone stem cell
What is a Osteoblast cell?
Bone forming cell
secretes ‘osteoid’
catalyse mineralisation of osteoid
What is a Osteocyte cell?
Mature bone cell
When osteoblast has is imbedded in its secretions
Sense mechanical strain to direct osteoclast and osteoblast activity
What is a Osteoclast cell?
Bone breaking
Dissolve and resorb bone by phagocytosis
Derived from bone marrow
Where are Osteogenic cells found?
Deep layers of periosteum
Where are Osteoblasts found?
Growing portions of bone - periosteum and endosteum
Where are Osteocytes cells found?
Entrapped in matrix
Where are Osteoclast cells found?
Bone surfaces and at sites of old, injured or unneeded bone
What composes the organic component of Bone matrix? (40%)
Type 1 Collagen ( 90% )
Ground substance ( 10% ) = Proteoglycans, Glycoproteins, Cytokine and growth factors
What composes the inorganic component of Bone matrix? (60%)
Calcium hydroxyapatite
Osteocalcium Phosphate
What are the characteristics of immature bone?
Laid down in a woven manner so is quite weak
Later mineralised and replaced by mature bone
What are the characteristics of mature bone and what types are there?
-Minersalized woven bone and have lamellar structure increases strength
- Corticol mature bone can bear weight
- Cancellous mature bone cannot bear weight
What are the characteristics of Cancellous bone and how does it differ from corticol bone?
Both found in flat bones of femur and skull
Cortical is the tough shell like bone on the outside. Made of Osteons.
Cancellous bones are light, inside flat bone and have airspaces.
What is a Osteon?
Unit of bone ( found in compact bone )
How are Osteon’s organised?
Repeated structural units, concentri lamellae around a central haversian canal : which contains blood vessels, nerves and lympathics
What is Lacunae and Volkmans canal?
( both a part of compact bone Osteon structure)
Lacunae : small spaces with osteocytes. Tiny canalculi radiate from lacunae filled with extracellular fluid
Volkman’s canal : transverse performating canal
- Youtube video linked ppt slide 20
What is the structure of long bone?
connective tissue surrounding called periosteum
Outer cortex: compact bone
Cancellous bone
Medullary cavity: contains yellow bone marrow
Nutrient Artery
Articular cartilage: on surface of bone at a joint only * articular cartilage is HYALINE cartilage on articular surfaces
- use ppt diagram slide 21
What two types of bone growth are there?
Interstitial and Appositional
What is Interstitial growth?
Long bone lengthening
Occurs as physeal plate
Epiphyseal side - hyaline cartilage active and dividing to form hyaline cartilage matrix
Diaphyseal side - cartilage calcifies and dies and then replaced by bone
What is Appositional growth?
bone increasing beneath the peristeum to increase thickness
ridges in periosteum create groove for new blood vessel
ridges fuse to form endosteum lined tunnels
Osteoblats build new amellae inward toward tunnel forming new osteon
So bone grows outwards as osteoblast sin peristeum build new cirumferential lamellae.
Osteon formation repeats as new ridges fold over blood vessel
How does does bone 🦴 relate to calcium homeostasis?
Calcium hydroxyapatite is used in bone for structural support
Calcitriol and PTH ( and calcitonin ) effects calcium deppositoin and removal.
- Increase Ca in blood : calcitonin increase = osteoclast inhibition, more osteoblast activity.
- Decrease Ca in blood : PTH causes Osteoclasts to release Ca from bone
How to classify joints?
Fibrous - sutures, sundesmosis, interosseous membrane
Cartilaginous -Synchodorses e.g. spine
Symphyses e.g. pubic
Synovial - Plane, Hinge, Condyloidm pivot, saddle, ball and socket
What are the characteristics of synovial joints?
Most common and allows most mobility
The joint capsule : Articular capsule on outside - keeps bone together and allow low friction
Synovial membrane on inside - contains synovial fluid
It is secreted into synovial cavity to reduce friction
What is the difference between the hinge joint and ball and socket?
Hinge ( ankle, elbow ) - can work in one plane
Ball and socket ( hip ) can move in 3 planes - x, y, z
What do Ligaments do?
Joint stability:
Between bones - prevent excessive movement
More ad tighter ligaments - good stability but less mobility or vice versa
Poor stability can cause risk of dislocation
Stress to ligament can cause injury
*muscular tone and joint capsule type also has effect
What can excessive ligament laxity cause?
Hypermobility - greater risk of injury
