This document provides information on bone structure and composition. It discusses the different types of bones and bone cells. The key parts of long bones are described, including the epiphysis, metaphysis, and diaphysis. Both compact and spongy bone tissue are examined. Other structures like the periosteum, endosteum, and bone marrow are also summarized. The document concludes with sections on blood supply and nerve innervation of bones.

1. Dr. Urfeya Mirza
Department of Veterinary Surgery & Radiology

2. 
 Bone is a highly vascular, living, constantly changing
mineralized connective tissue
 It is provided with vessels and nerves
 Consists of bone cells (osteocytes), embedded in a matrix
of calcified intercelluar substance
 Bone matrix composed of organic materials,mainly
collagen fibres & inorganic salts rich in calcium &
phosphate
Introduction

3. Long bones
Short bones
Flat bones
Irregular bones
Sesamoid bones
Sutural bones

5. 

6. 

7. 
1. Osteocytes ("bone cells") – mature cells separated
by intercellular substance
2. Osteoblasts ("bone makers") – bone producing
cells
3. Osteoclasts (“bone breakers”) – bone removing
cells
4. Osteoproginator cells (Pleuripotent stem cells) –
from which osteoblasts and osteoclasts derived
Bone Cells

11.  Shaft – Thick compact bone+ medullary cavity
 Ends - Cancellous bone + thin compact layer
 Articular cartilage – No periosteum, avascular
 Periosteum – Fibrous + cellular
(Shape, nutrition, attachment, fracture repair, sensitive)
 Endosteum – Cellular -Repair and remodelling
 Nutrient foramen – mid shaft
 Bone marrow – Red, Yellow

12. Parts of a growing bone
 Epiphysis
(Secondary)
 Epiphyseal
plate
 Metaphysis
 Diaphysis
(Primary)

13.  Epiphysis
• Are expanded articular ends
• Separated from the shaft by the epiphyseal plate
during bone growth
• Composed of a spongy bone surrounded by a thin
layer of compact bone.
 Proximal epiphysis
 Enlarged terminal part of the bone,
 Nearest the center of the body
 Distal epiphysis
 Enlarged terminal part of the bone,
 Farthest from the center of the body

14.  Metaphysis
 Part of the bone between the epiphysis and the
diaphysis
 It contains the connecting cartilage enabling the bone
to grow
 Disappears at adulthood
 Diaphysis
 Elongated hollow central portion of the bone located
between the methaphyses
 Made of compact tissue
 Encloses the medullary cavity.

15. 

16.  The outer surface of the bone is covered by a
membrane except at the cartilage known as
Periosteum and a thin membrane invests the
medullary cavity known as Endosteum
 Bones are composed of two types of substances –
compact and spongy
• Compact(Lamellar)bone: Outer cortical part of long
bones, which is hard & homogeneous in appearance.
• Spongy(Cancellous) bone: The inner part of long
bones, less hard & presents a spongy appearance.

19. Compact Bone (Lamellar bone):
The basic structural unit of compact Bone is
Haversian system or Osteon, named after Clopton
Havers(1691).
It contains following structures:
• Haversian canal
• Lamellae
• Lacunae
• Canaliculi
• Volkamann's canal

20.  A bony tissue arranged in a definite pattern is
known as Haversian System or Osteons
 Numerous very narrow canals pass through the
compact substance along the length of the bone are
known as Haversian canals, which carry blood
vessels and nerves
 Around these canals bone matrix is present in the
form of several concentric lamellae
 In between the lamellae there are minute spaces
known as Lacunae which give accommodation to the
bone cells – the osteocytes
 Very minute canals radiate from these lacunae to
accommodate the processes of bone cells. These are
called Canaliculi

21.  In between Haversian Systems the triangular areas
are filled up by irregular bony deposits called
interstitial lamellae
 The Haversian canals communicate with the spongy
bones, marrow cavity and with surface of the bones
by some transverse canals which are not surrounded
by bony lamella which are known as Volkmann’s
canals

26. Spongy Bone : (Cancellous bone)
• A large number of very small bony plates
(trabeculae) unite irregularly enclosing small
marrow spaces between them and form a hard
structure of spongy appearance, known as spongy
substance which make the bulk of small and
irregular bones as well as the ends of long bones
• There is no Haversian system of arrangement in the
spongy substance
• The bony trabeculae are arranged along the line of
maximal internal stress in such a way that the bone
can resist stress and strain to which it is subjected

30. Periosteum:
• Bones are covered by a membrane except
at the articular surfaces known as
Periosteum
• Its outer layer is fibrous (collagen) and
inner layer is cellular
• The cellular layer contains osteoblast cells
which help in ossification and hence called
osteogenic layer
• Periosteum is not present on the sesamoid
bones
Endosteum:
• The marrow cavity and various marrow
spaces are lines by a layer of areolar tissue
which is very rich in fine blood vessels,
this lining membrane is known as
Endosteum

34. Articular cartilage:
• Most of the articular cartilages are hyaline in nature
• Cells of these cartilages are almost round or
elongated and are arranged singly or in groups of
even number of cells
• The ground substance is either transparent or
granular in appearance
• This cartilage normally does not ossify
• It derives nutrition from synovial fluid and
surrounding cells

35. Bone Marrow:
• The medullary cavity of long bones and marrow spaces of
all the bones are occupied by a soft and pulpy tissue,
known as bone marrow
• There are two types of bone marrow – yellow and red. At
birth and in the prenatal life most of the marrow is red
and with the advance of age, yellow marrow replaces the
red marrow
• Red marrow consists of reticular connective tissue,
various blood cells at their different stages of
development, megakaryocytes, fat cells, lymphoid cells
and blood vessels
• Yellow marrow consists of connective tissue, blood
vessels, fat cells and also some mature and immature red
blood cells

37. 
1. Nutrient artery
2. Periosteal artery
3. Epiphysial artery
4. Metaphysial artery
Blood Supply

38. Nutrient artery
1. Enters through the nutrient foramen
2. Divides into ascending and
descending branches in the
medullary cavity
3. Branch divides – small parallel
channels – terminate in adult
metaphysis
4. Anastomosing with the epiphysial,
metaphysial and periosteal arteries
5. Supplies the medullary cavity , inner
2/3 of the cortex and metaphysis
6. Nutrient foramen is directed away
from the growing end of the bone

39. Periosteal arteries
1. Numerous beneath the
muscular and ligamentous
attachments
2. Ramify beneath the
periosteum and enter the
volkmann’s canals to supply
the outer 1/3 of the cortex

40. Epiphysial arteries
1. Derieved from periarticular
vascular arcades (circulus
vasculosus)
2. Out of the numerus vascular
foramina in this region – few
admit arteries and rest venous
exits
Metaphysial arteries
1. Derived from the
neighbouring systemic vessels
2. Pass directly into the
metphysis and reinforce the
metaphysial branches from
the primary nutrient artery

42. 
 These are most numerous in articular extremities of
long bones, vertebrae and larger flat bones
 Nerves occur widely in periosteum, fine myelinated
and non-myelinated fibres accompany nutrient
vessels into bone marrow and lie in perivascular
spaces of Haversian canals
Nerve Supply