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