anatomy

1. ANATOMY AND HISTOLOGY OF BONE
PROFESSOR & HOD,
DEPTT OF ORTHOPAEDICS,
SILCHAR MEDICAL COLLEGE AND HOSPITAL

2. FUNCTION OF BONE
Serves as attachment sites for muscles.
Protection of organs(eg cranium,ribs
and pelvis).
Acts as reservoir for mineral in the body
99% calcium stored as hydroxyapatite
crystals.

3. BONE FORMS
LONG BONES
Formed by
enchondral
ossification.
Primary in shaft and
and sec. growth
centers
FLAT BONES
Formed by
intramembranous
ossification.
eg pelvis,scapula.

4. PARTS OF LONG BONESs
DIAPHYSIS-Shaft,made of thick cortical
bone,filled with bone marrow.
METAPHYSIS –Widening of bone near
the end made of cancellous bone.
EPIPHYSIS –End (usuallyarticular) of
bone,forms from secondary ossification
centers.

7. MICROSCOPIC BONE TYPES
WOVEN- Immature or pathologic bone,
poorly organised not stress oriented.
eg bones in infants ,fracture callus and
pathological tumours.

8. LAMELLAR TYPES
Mature bone highly organised with stress
orientation.
Mature cortical and cancellous bone are
made of lamellar bones.

10. STRUCTURES OF CORTICAL
BONES
Strong dense bone,constitute 80% of skeleton.
Composed of multiple osteons.
Osteons are made up of concentric bone
lamellae with a central canal(haversian canal)
containing osteoblasts.

13. Lamellae are connected by canaliculi,
cement lines mark outer limit of osteon,
cortical bone is found in diaphysis of long
bones.
Volkmann′s canals – radially oriented ,
have arteriole and connect adjacent
osteons.

14. STRUCTURE OF CANCELLOUS
BONE
 Crossed lattice structure,makes upto
20% of the skeleton.
 High bone turnover rate,bone is resorbed by
osteoclasts in howship lacunae and formed on the
opposite side of trabeculae.
 Osteoporosis is common and found in vertebral
bodies,femoral neck,distal radius , tibial plateau and
found in metaphysis and epiphysis.

17. BONE COMPOSITION
 Inorganic phase – 1)calcium
hydroxyapatite.
2)Osteocalcium phosphate.
Organic phase
1)collagen
2)Proteoglycans

18. 3)Non collagenous proteins.
4)Cells
Water approx. 5 % of bone weight.
Periosteum surrounds the bone and is thicker in
children,responsible for growing diameter. .

19. INORGANIC PHASE
Approx 60% of body weight.
Ca10(po4)6(OH)2 is primary mineral in bone.
Adds compressive strength .
Brushite is secondary mineral in bone.

20. ORGANIC PHASE
Collagen
Known as osteoid before its mineralization
Approx 35% of bone weight.
Type 1 collagen gives tensile strength.
Proteoglycans – Hyaluronic backbone with
multiple glycosaminoglycans.
gives compressive strength.

21. Non collagenous protein- Osteocalcin
is indicator of bone turnover rate.
eg Pagets disease.
 osteonectin and osteopontin.
Cells include osteoblasts,osteocytes and
osteoclasts.

22. OSTEOBLASTS
Produce bone matrix ,makes type 1
collagen.
Follow osteoclasts in cutting cones.
 Receptors –PTH ,vitamin D,glucosteroids
estrogens,PGs.

23. OSTEOCYTES AND OSTEOCLASTS
Osteoblast surrounded by bone matrix cons
90% of bone cells.
Preserves bone,long cell process
communicate via canaliculi receptors include
PTH and calcitonin.
Osteoclast are large multinucleated derived
from monocytes and macrophages absorbs
bone and found in howship lacunae.