This document discusses bone formation and development. It describes two types of bone formation: intramembranous ossification where bones develop within membranes, and endochondral ossification where cartilage is replaced by bone. Skull bones, face bones, and clavicle develop through intramembranous ossification, while long bones develop through endochondral ossification starting with cartilage models. Primary ossification centers form before birth while secondary centers form after birth and fuse the epiphyses to the diaphysis. The document also discusses arterial blood supply to bones.

1. GENERAL
ANATOMY
R.M.F

2. MR.Rana
Muhammad Furqan
MISS. Fiza
MISS. Saba

3. CHAPTER NO 3
Bones & Cartilages

4. Bonesdevelop
through a process
called Osteogenesis.
Primitive skeleton of
embryo is composed
of fibrous membrane
or hyaline cartilage .

5. ❖ Intramembranous osteogenesis
❖ Intracartilaginous osteogensis

6. ➢ In this type ,immature connective tissues called
mesenchyme.
➢ Bone forming cells called osteoblast .
➢ Osteoblasts unmineralized bone matrix called
osteoid.
➢ Osteoid become mineralized by calcium
phosphate
➢ Intramembranous is quick method of bone
formation and bone development.

7. Skull bones develop
by
intramembraneous
osteogenesis
Bones of face
develop by
intramembraneous
osteogenesis
Bone of clavical
develop by
intramembraneous
osteogenesis

8. ➢ Miniature cartilaginous model of bone is first
formed.
➢ Bone formation begins in the center ,as the
primary center of ossification.
➢ Secondary center of ossification appear in the
bone end in the few months or in a few years
later.
➢ In the endochondral osteogensis , the hyline
cartilage is not converted into bone but it is
completely replaced bye bone tissues

9. ➢ when a baby is formed bone formation is still in complete.
➢ There is considerable membrane left around in each intramembranous
bones.
➢ The endochondral bones still retain some cartilage .
➢ The cartilaginous plate remain b|w diaphysis & epihysis.
➢ Epihysis cartilage continue to grow.
➢ A new bone is formed at diaphyseal end of the growing plate.

11. Primarycentre of
ossificationissingle
and appear before
birth.
Exception -Carpal
bones.
Secondarycentres
of ossificationcan
be singleor
multiple and
appearsafter birth.
Exception - Lower
end of femur.
The centres that
appear first, fuse
last.
Exception - Lower
end of fibula.

12. The secondary centers fuse
together to form a single
epiphysis, which in turn,
fuses with the diaphysis.
Exception -Upper end of
humerus.
The direction of the nutrient
artery is opposite to the
direction of the growing end
of the bone.

13. ❑ Arterial Supply :

14. Nutrient
artery
Metaphyseal
artery
Epiphyseal
artery
Periosteal
artery

15. ▪ Nutrient artery enter the shaft of the bone
▪ Run through the bone cortex in the nutrient canal
▪ In the medullary cavity it divides into ascending &
descending branches

17. ▪ These branches referred to as medullary arteries
▪ Approach the epiphyses , medullary artery divide and give rise numerous
branches
▪ These branches are end arteries that drain into venous capillaries

18. ▪ Some branches of medullary arteries anastomose with the terminal branches
of the metaphyseal & epiphyseal arteries.
▪ This constituents is an important collateral route for the suppluy of blood to the
bone shaft , if medullary artery is damaged .