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Flashcards in Bone tissue Deck (16):

What is osteology?

the study of bones


what is osseous tissue



the hardening process of bones is called

calcification/ mineralisation


list types of bones

flat bones
short bones
long bones
irregular bones


list flat bone examples

cranial bones
hip bones


list long bones



list short bones



list irregular bones



general anatomy of long bone

-enclosed by outer compact (dense/lamellar) bone
-medullary cavity for bone marrow
-at the end of the bone the central space is occupied by loosely organised form of osseous tissue called spongy (cancellous) bone
epiphyseal line

- externally bone is covered in sheath called periosteum
which provides strong attachment for muscles and tendons

- in kids - epiphyseal plate of hyaline cartilage separates the marrow spaces of the epiphysis and diaphysis


bone cells

-osteogenic (osteoprogenitor cells) are stem cells that develop fromn embryonic mesenchymal cells
found in the endosteum
they multiply and continually and go on to form into osteoblasts
-osteoblasts - are bone forming cells
-osteocytes - former osteoblasts, that have become trapped in the matrix they deposited
-osteoclasts - bone dissolving cells


what is the formation of bone called

ossification or osteogenesis


two methods of formation of bone

intramembranous and endochondral ossification

intramembranous - produces flat bones of the skull and most of the clavicle

endochondral - process whereby the bone is preceded by hyaline cartilage model


where is the thickest part of a long bone

the middle of the shaft - where most stress is applied


classification of fractures

stress fracture- caused by abnormal trauma to a bone, such as fractures incurred in falls, athletics and military combat
pathological fractures - break in bone weakened by some other disease, such as bone cancer, osteoporosis, usually caused by a stress that would not normally fracture a bone
- also classified by direction of fracture line, whether the skin is broken or not, whether the bone is cracked or broken into separate pieces


stages of bone healing post fracture

1- formation of hematoma and granulation tissue
a bone fracture severs blood vessels of the bone and periosteum, causing bleeding and the formation of a blood clot (fracture haematoma). blood capillaries soon grow into the clot, while WBCs invade the tissue from both the periosteal and medullary sides of the fracture. Osteogenic cells become very abundant within the 48 hrs of injury. All of the capillary and cellular invasion converts the blood clot to a soft fibrous mass called granulation tissue
2- formation of a soft callus - fibroblasts deposit collagen in the granulation tissue, while some osteogenic cells become chondroblasts and produce and produce patches of fibrocartilage called the soft callus
3- conversion to hard callus- other osteogenic cells differentiate into osteoblasts which produce a bony collar called the hard callus - it takes 4-6 weeks for the hard callus to form - important that a broken bone be immobilised by traction or a cast to prevent re injury
4- remodelling - hard callus persists for 3-4 months
meanwhile osteoclasts dissolve small fragments of broken bone and osteoblasts deposit spongy bone to bridge the gap between the broken ends. gradually fills to become compact bone in manner similar to intramembranous ossification.


Treatment of fractures

closed reduction - a procedure which the bone fragments are manipulated into their normal positions without surgery

Open reduction - surgical exposure of the bone and the use of plates, screws, pins to realign fragments.

to stabilise bone during healing fractures are often set in casts.
traction is used to treat fractures of the femur in children - it aids in the alignment off the bone fragments by overriding the force of the strong thigh muscles.