20. Bone cells -Function
• Osteoblasts – Matrix synthesis – Osteoid,
Calcification
PTH receptors
• Osteocyte – Maintanace of Matrix by intercellular
sickling systems
• Osteoclast – Digestion of collagen,
dissolving hydroxyapatite
* Calcitonin receptors
21. Bone cells- Medical application
Rate of bone apposition – Bone growth
Osteomalacia – Impaired mineralization
Osteitis fibrosa cystica – osteoclast activity
Osteopetrosis – “Marble bones” – Bone resorption
defect due to osteoclastic activity
Osteitis deformans (Paget’s disease) –Uncontrolled
osteoclast activity followed by osteoblastic activity
(incomplete)- Stops at osteoid level
22. BIOCHEMISTRY
1.INORGANIC 65 -70%
2.ORGANIC 30-35%
ORGANIC: a. collagen 90-95%
b. pps 4-5%
c.Lipids 0.1%
INORGANIC 90% Calcium and phosphate
23. BONE COLLAGEN
1.AXIAL PERIODICITY OF 640 TO 700A
2.PROTIEN COMPOSITION WITH ONE THIRD GLYCINE
3.LARGE NO. OF ALANINE RESIDUES
4.CYSTEINE IS COMPLETELY ABSENT
29. PRESSURE
region of the long bone that forms the joint is called Pressure Epiphysis
ARTICULAR....WT TRANSMISSON
EX: HEAD OF FEMUR AND HUMERUS
TRACTION
Non-articular
Muscle pull
Ossifies later than Pressure
.EX HUMERUS G.T AND L.T
FEMUR G.T AND LT
33. ZONE 1
INJURY CAUSES CESSATION OF GROWTH
ZONE 2
BONE LENGTH IS ADDED
ZONE 3
WEAKEST PORTION OF GROWTH PLATE
34. Metaphysis
Epiphyseal end
of diaphysis
Active growth
Before fusion
end arteries, hair
pin bends
OSTEOMYELITI
S
35. Blood supply of bones
Long Bone
Nutrient artery
Metaphyseal arteries
Epiphyseal arteries
Periosteal arteries
Short Bone - Nutrient artery;
Periosteal arteries
Vertebra- Body, Processes
Rib - Nutrient artery; Periosteal
arteries
36. Nutrient artery
Mid shaft
Tortuiosity
2/3rd inner compact bone
Hair pin loops
Direction – away from
growing end
.
“To the elbow I go.
From the knee I flee.”
37. Nutrient Artery
1.Enters into the diaphysis of long bones
through an oblique canal
2.direction of canal is determined by relative
amount of growth that has occurred at
proximal and distal ends of the bone;
3.does not branch within the cortex, divides
after reaching the medullary cavity,
4. direction of blood flow is centrifugal;
38. Disruption of Nutrient Artery causes
1. In growing bone can result in necrosis of large portion
of marrow & of inner two thirds of cortex
2. This cortical death does not occur in adult bone
because combined epiphyseal-metaphyseal collateral
circulation is developed enough to maintain these
areas;
3.loss of circulation in terminal vessels of nutrient artery
of growing bone will interfere with enchondral
ossification;
39. Epiphyseal arteries
In femoral and radial heads, which
are almost entirely covered by
cartilage vessels enter in region
between articular cartilage &
growth-plate cartilage
In other regions, the epiphysis has
openings that permit passage of large
number of vessels into and out of the
ossification centers
40. Obliteration of epiphyseal blood supply
causes
1.necrosis of epiphysis
2. longitudinal growth ceases
3. permanent closure of epiphyseal plate
41. METAPHYSIAL ARTERIES
BRANCHES OF SYSTEMIC VESSELS
Epiphyseal vessels are responsible for permitting longitudinal
growth to occur, whereas metaphyseal vessels nourish
osteoprogenitor cells, which lay down bone on cartilage
matrix;
42. PERIOSTEAL ARTERIES
Periosteal vessels send small branches thru minute channels in cortex to
supply about outer 1/3 of cortex
Extensive network of vessels covers entire length of the bone shaft
Anastomoses with adjacent skeletal muscles so in cases in which the
nutrient artery of muscle has been damaged, then periosteal vessels
may temporarily serve as the primary blood supply;
43.
44. BLOOD SUPPLY OF GROWTH PLATE
growth plate itself is avascular & receives nutrition from 2 sources
1.epiphyseal vessels that supply germinal, proliferating, and upper
hypertrophic cell layers by diffusion
2 .metaphyseal vessels that supply zone of
provisional calcification
45. In a young child, epiphyseal vessels are
separated from metaphyseal vessels, but
following growth arrest of the cartilage plate,
there is
an extensive anastomoses between
epiphyseal vessels, metaphyseal vessels, &
terminal branches of Nutrient Artery;
46. VENOUS DRAINAGE
TRANSVERSE VENOUS CHANNELS
CENTRAL VENOUS SINUS
NUTRIENT VEIN
-ONLY 5-10% OF VENOUS DRINAGE IS THROUGH NUTRIENT
VEIN
-REMAINING IS THROUGH PERIOSTEAL VENOUS DRINAGE
47. Circulatory disturbances
PHYSIS AND EPIPHYSIS
1.Legg–Calve–Perthes Disease: Circulatory disturbance to the capital
femoral epiphysis
2.Physeal Trauma
METAPHYSIS
1.Haematogenous Osteomyelitis
2.Metastasis.
DIAPHYSIS
1.Intramedullary Reaming
2.Fracture Healing
PERIOSTEAL BLOOD SUPPLY
1.Paralytic conditions
48. Spongy bone
1. loose network of bone trabecule
2. interconnected
3. arranged along lines of maximum stress
54. Sharpey’s fibers
Connective tissue matrix
Bundles of collagen fibers
Connect Perisoteum to
Bone
Fibrous layer of
Periosteum to
outer circumferential
and interstitial lamellae
56. Factors affecting growth of a bone
Nutritional
Vit. A - Co-ordination of osteoblastic and
osteoclastic activity
Vit.C – Synthesis of organic matrix
Vit.D – Absorption of Ca, P
Rickets, Osteomalacia
(Calcification deficiency)
Calcium – Decalcification of bone
57.
58. Factors affecting growth of a bone
Hormonal –
• Pituitary - GH- Dwarfism; Gigantism,
Acromegaly
• Thyroid - Calcitonin
Parathyroid – PTH Decalcification
Sex Hormones - Androgens, estrogens - Stimulators
Mechanical factors
Tensile forces – Bone formation
Compressive forces – Bone resorption
60. Rules of Ossification
Primary centers - before birth
except carpal and tarsal (except calcaneus, talus,
cuboid)
Secondary centers - after birth
except lower end of femur, upper end of tibia,
humerus
Center which appears first unites last
except lower end of FIBULA
61. Rules of Ossification
Center which appears later unites first
except upper end of fibula
Direction of nutrient artery - away from
growing end
except fibula
Growing end is one where center
appears first and unites last
except fibula