1. BONE
CAPT DR POONAM SINGH

2. BONE
1.
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7.
8.
INTRODUCTION
FUNCTIONS
CLASSIFICATIONS
PARTS OF GROWING
LONG BONE
BLOOD SUPPLY OF A
LONG BONE
HISTOLOGY
DEVELOPMENT
APPLIED

3. INTRODUCTION
• Specialized CT with a solid matrix which is
mineralized & adapted for giving strength,
support & helping in wt transmission.
• Inorganic material ( calcium phosphate, traces
of other salts..) provides hardness & rigidity
to the bone radiopaque in XR.

4. FUNCTION
1. Shape & support
( forms framework)
2. Protection
3. Movement
4. Storage
5. Blood cell formation
6. PNS:- Resonance to
voice

5. REGIONAL CLASSIFICATION
Axial skeleton (80)
 Skull & facial bones
 Vertebral column
 Thoracic cage
Appendicular skeleton (126)
 Upper limb: Girdle & free bones
 Lower limb: Girdle & free bones
 206 number is not exact; varies

6. DEVELOPMENTAL CLASSIFICATION
1) Membranous bones
• Ossify in membrane
• Derived from mesenchymal condensation
Bones of skull vault & facial bones
2) Cartilaginous bones
• Ossify from cartilage
• Derived from preformed cartilage models
Bones of limbs & vertebral column
3) Membrano-cartilaginous bones
• Dev by both

7. STRUCTURAL CLASSIFICATION
(MACROSCOPICALLY)
1. COMPACT BONE:- Hard & dense , resembles ivory
- No visible spaces.
• Consists of :- Lamellae of collagenous sheets
- Haversian system / Osteons

8. COMPACT BONE
Lamellae :- 3 types
1. Concentric: surrounds
Haversian canal
2. Interstitial: lie between
osteons
3. Circumferential: flat
plates extend around
the bone

9. STRUCTURAL CLASSIFICATION
(MACROSCOPICALLY)
2. CANCELLOUS BONE:- Sponge work of trabeculae,
trabeculae are oriented along
lines of stress.
- Large spaces filled with red bone
marrow.
- Osteoblasts +nt on their
surfaces.

10. STRUCTURAL CLASSIFICATION
(MICROSCOPICALLY)
1). Woven bone
- Warp & weft of a woven fabric.
- Eg.. Young fetal bones
Callus at # sites
2). Lamellar bone
- mineralized matrix arrange in thin layers.
- 2 diff patterns
a) concentric cylindrical units. Eg. Compact bone
b) branching & anastomosing curved plates. Eg. Spongy
bone

11. MORPHOLOGICAL CLASSIFICATION
1.
2.
3.
4.
5.
6.
7.
Long bones
Short bones
Flat bones
Irregular bones
Pneumatic bones
Sesamoid bones
Accessory bones

12. LONG BONES
- Length exceeds the breadth & thickness.
- confined to limbs
- one elongated shaft & 2 expanded ends
- Shaft has medullary cavity, typically has 3
borders & 3 surfaces
- Ossify in cartilage: 1 primary and 2
secondary ossification centre
- Are weight bearing
- May be
– Typical- Humerus
– Miniature- One epiphysis
(Metatarsals)
– Modified- No medullary cavity
(Clavicle)

13. SHORT BONES
• Cubical or modified cubes
• Have generally 6 surfaces; 4/ less
are articular, & 2/ more for
attachments of ligaments & for
blood vessels to enter
• Develop in cartilage
• Begin to ossify after birth
– Eg..Carpals & tarsals

14. Flat bones
• Resemble sandwiches
• Consists of two layers of
compact bone & marrow
spread between them
• Form boundaries of certain
bony cavities
– Eg..Bones of skull vault,
Scapula

15. IRREGULAR BONE
• Irregular or mixed shape
• Composed of spongy
bone & marrow in
compact covering bone
– Eg..Vertebrae, Hip
bone

16. PNEUMATIC BONE
• Irregular bones which contain
air spaces lined with mucous
membrane
• Typically in skull bones
• Make the skull light
• Impart resonance to voice
• Act as conditioning chambers
for inspired air
– Eg..Maxilla, Ethmoid

17. SESAMOID BONES
-Develop in some tendons
-Periosteum absent
-Rubbing surface is covered with
articular cartilage
-Appear after birth usually by multiple
centers
-Lacks haversian systems.
Functions
1) Minimize friction
2) Alter direction of pull of muscle
3) Act as pulleys for muscle contraction
Eg….Patella, Pisiform

18. ACCESSORY BONES
• Generally not +nt in our body
• s/t clinicians confuse with
fractures
• Formed due to non fusion of
epiphysis
• Appearance of extra
ossification centers in skull

19. GENERAL STRUCTURE
1. Outer surface: Periosteum ( dense fibrous
CT)
-Tendons & ligaments attach to bone &
become
continuous with fibers of periosteum.
- Sharpy’s fibers: some collagen fibers of
tendons or ligaments penetrate the
periosteum and into the bone. Strengthen
attachment of tendon or ligaments to bone.
2.
Bony cavities: Endosteum (thin CT)
Bone marrow ( red & yellow)
More cellular

20. PARTS OF GROWING LONG BONE
• 2 ends & a shaft.
• Before ossification:1). Epiphysis - types
2). Epiphyseal plate
3). Metaphysis
4). Diaphysis

21. BLOOD SUPPLY OF LONG BONE
1. Nutrient / Medullary Artery
• Main artery of shaft
3
4
• Enters at nutrient foramen; runs
obliquely thru cortex
• Divides into ascending &
descending branches in
medullary cavity
• Each subdivides into small parallel channels
terminating in metaphysis
• Supplies: Medullary cavity, Inner 2/3 cortex
& Metaphysis
1
2

22. BLOOD SUPPLY OF LONG BONE
2. Periosteal arteries:
• Enter at many points , numerous, ramify
beneath the Periosteum
• Enter the bone thru Volkmann's canal
• Supply: Outer 1/3rd cortex
3. Epiphyseal arteries:
From periarticular vascular arcade
4. Metaphyseal arteries:
derived from neighboring arteries & enter
the metaphysis directly along the attachment
of jt capsule

23. MICROSCOPIC STRUCTURE OF BONE
• Cells + Matrix ( ground substance + fibers)
Fibers:- Type I collagen fibers
-mechanical strength & elasticity
Ground substance:1) 1/3 Organic:- Proteoglycans, glycoprotein,..
2) 2/3 inorganic:- Hydroxyapatite CaPO4 crystals
IN MATURE BONE
10-20%= Water
60-70%= Inorganic mineral salts
30% = Collagen
Remainder= Non-collagenous protein & carbohydrates

24. BONE CELLS
• CELLS:- 5 Types
1. Osteoprogenitor
cells
2. Osteoblasts
3. Osteocytes
4. Bone lining cells
5. Osteoclasts

25. OSTEOPROGENITOR CELLS
• Derived from mesenchymal stem cells.
• Osteoblasts precursor cells.
• Flattened , elongated ovoid nuclei.
• Transcription factor CBFA1 ( RUNTX2)
• Location:- Periosteum, endosteum,
stromal component of BM.

26. OSTEOBLAST
• Differentiated bone- forming cell that
secretes bone matrix.
• Shape:- Cuboidal / polygonal.
• Nucleus:- eccentric
• fxns:
1.Synthesize & secrete osteoid
2. Mineralization of matrix

27. OSTEOCYTES
• Mature bone cell enclosed by bone
matrix.
• Oval, 25µ in long axis
• Prominent nucleus
• Cell lacunae
Processes Canaliculi
• Fxn:- 1)Maintains bone tissue.
2)Mechanotransduction.
3)Calcium homeostasis

28. BONE LINING CELLS
• Inactive Osteoblasts.
• Flattened
• 2 types:-Periosteal cells
-Endosteal cells

29. OSTEOCLASTS
• Large , multinucleated
cells found at sites
where bone is being
removed.
• Cells lie in pit:Resorption bay
(Howship’s lacunae).
• Helps in resorption of
bone and remodeling.

32. OSTEON

33. Bone Ground Section T.S

34. Bone Ground Section L.S

35. Compact Bone TS (H&E)

36. Spongy Bone/ Trabecular Bone

37. Bone Development
• All the bones develop from a mesenchyme.
• Two types of ossification:1) Intramembranous
-Takes place in connective tissue membrane.
2) Intracartilaginous/ Endochondral
-Takes place in cartilage.

38. INTRAMEMBRANOUS OSSIFICATION
•
Takes place in CT membrane formed from embryonic
mesenchyme
•
Skull bones, Part of mandible, Diaphyses of clavicles
•
Centers of ossification: appear in membrane where
ossification begins (centers of ossification expand outwards to form a
bone by gradually ossifying the membrane)
•
Fontanels: large membrane-covered spaces between
developing skull bones; unossified (bones eventually grow
together & all fontanels have closed by 2 years of age)

39. INTRACARTILAGINOUS OSSIFICATION
• Cartilage formation begins at end of 4th wk of
development.
• Some ossification begins at about 8th wk; some
does not begin until 18-20 years of age.
• Bones of the base of the skull,
Part of the mandible,
Epiphyses of the clavicles,
Remaining bones of skeletal system.

40. INTRACARTILAGINOUS OSSIFICATION

43. Zones of the Epiphyseal Plate

44. Growth in Bone Length

45. FRACTURE OF BONE
1. Simple / closed #
2. Compound / open #
T/t :- realigning the
broken ends & then
immobilizing them
until # is healed.

46. REPAIR OF FRACTURE

48. RICKETS
• Softening of bones in immature
mammals
• Frequent chilhood disease in many
developing countries
• Cause:1). deficiency or impaired metabolism
of vitD, phosphorous
or Ca++ fractures and deformity.
2). severe diarrhea and vomiting may
be the cause of the deficiency
3). severe malnutrition

49. OSTEOMALACIA
• softening of the bones caused by defective bone
mineralization.
• Cause:- inadequate amounts of available phosphorus and calcium
- overactive resorption of calcium from the bone as a result
of hyperparathyroidism.
- vitamin D deficiency
• Signs:- diffuse body pains
muscle weakness
fragility of the bones

50. OSTEOMYELITIS
• infection and inflammation of the bone or
bone marrow.
OSTEOPOROSIS
• Bone mineral density(BMD) is reduced
• bone micro architecture deteriorates
• the amount and variety of proteins in bone are
altered.
• Fractures are the most dangerous aspect of
osteoporosis.

51. OSTEOPHYTE (bone spur)
-commonly referred to as bone spurs or parrot beak
-bony projections that form along joint margins
Sites:1) Back of the spine.
2) Feet either along toes or heel.
3) Hands.
Osteophytes on the fingers & toes :Heberden’s node,if +nt on the
distal interphalangeal joint
& Bouchard’s node,
if +nt on the proximal IP jt.

52. POSHITIS
• Poshitis is a concept conceived in 2013
describing a Girl that Carry a heavy handbag
and get sick of it.
• The name is derived from Victoria
Beckham's use of heavy handbag's.

53. THANK YOU