This document provides an overview of bone anatomy and physiology. It discusses the objectives, introduction, functions, embryology, gross anatomy including long bone structures, bone markings, microscopic anatomy, composition, classification, and formation, growth, and remodeling of bone. It also covers the blood supply of bone and the roles of parathyroid hormone, calcitriol, and vitamin D in bone health.

1. Bone
Anatomy and Physiology
UNIT I
2076/02/30
Dr. Subhash Kumar Das
Resident
Department of Orthopaedics
SBH

2. OBJECTIVES
• Introduction
• Functions
• Embryology
• Gross anatomy of bone
• Bone markings
• Microscopic anatomy
• Composition
• Classification of bones
• Bone formation, growth and remodelling
• Blood supply
• Role of PTH, calcitriol and vit D

3. Introduction
• Bone is mineralized dense connective tissue
• Made up of few cells in mineralized matrix
• Consists of 30-40 % of our body weight.
• Dynamic in nature

4. Function
• Framework of the body.
• Attachment of muscle and tendon.
• Permit the movements in body parts.
• Protection of organs.
• Haematopoiesis
• Reservoir of minerals and fat.

5. Embryology
• Embryonic mesodermal cells
• Neural crest cells

7. Gross Anatomy of a Long Bone
Diaphysis
 Shaft
 Composed of
compact bone
 Epiphysis
 Ends of the bone
 Composed mostly of
spongy bone

8. Structures of a Long Bone
• Periosteum
Outside covering of the diaphysis
Fibrous connective tissue
membrane
• Sharpey’s fibers
Secure periosteum to
underlying bone
• Medullary cavity
Cavity of the shaft

9. Bone Markings
• Surface features of bones
• Sites of attachments for muscles, tendons,
and ligaments
• Passages for nerves and blood vessels
• Categories of bone markings
– Projections and processes – grow out
from the bone surface
– Depressions or cavities – indentations

12. Microscopic Anatomy of Bone
• Osteon (Haversian System)
– A unit of bone
• Central (Haversian) canal
– Opening in the center of an osteon
– Carries blood vessels and nerves
• Perforating (Volkman’s) canal
– Canal perpendicular to the central canal
– Carries blood vessels and nerves

14. Microscopic Anatomy of Bone
• Lacunae
– Cavities containing
bone cells(osteocytes)
– Arranged in
concentric rings
• Lamellae
– Rings around the
central canal
– Sites of lacunae

15. Microscopic Anatomy of Bone
• Canaliculi
– Tiny canals
– Radiate from the
central canal to
lacunae
– Form a transport
system

16. Composition of Bone
• Bone is a specialized connective tissue.
• It consists of cells and intercellular substance or matrix.
• Cells are:
Osteoblasts- precursor cells of osteocytes.
Osteocytes- Bone forming cells.
Osteoclasts- These cells helps in bone
resorption.
• Matrix:
Organic matrix= mainly type I collagen fibers
Inorganic matrix= calcium, magnesium, phosphate,
carbonate, chloride, fluride and citrate.

17. • Inorganic content give rigidity to the bone
• Organic content give the elasticity to the
bone.
• Lack of inorganic content- soft
bone(rickets/osteomalacia)
• Lack of organic content- brittle bone
(OI/lobstein syndrome)

19. Classification
• Regional classification
-Axial skeleton- 80 bones
-Appendicular skeleton-126
bones
• Microscopic classification
-Compact bone
-Cancellous/trabecular bone

20. Classification of Bones on the
Basis of Shape

21. Bone Formation, Growth and
Remodeling
• In embryos, the skeleton is primarily hyaline
cartilage
• During development, much of this cartilage is
replaced by bone

22. Bone Formation, Growth and
Remodeling
Ossification
– is the process of bone formation
• It involves two major phases:
– First, the hyaline cartilage model is completely
covered with bone matrix by bone forming
cells called osteoblasts.
– Then, the enclosed hyaline cartilage model is
digested away, opening up a medullar cavity
within the newly formed bone.

23. -

24. How do bones widen?
• Osteoblasts in the periosteum add bone to the
external face of the diaphysis as osteoclasts
in the endosteum remove bone from the inner
face of the diaphysis wall.
• Appositional growth
- The process by which the bones increase
in diameter.

25. • Bones are remodelled continually in
response changes in two factors:
-Calcium levels in the blood
-The pull of gravity and muscles on the bones

26. Wolff’s law

27. BLOOD SUPPLY OF BONE

28. Role of PTH, CALCITONIN and VIT D

29. THANK YOU