Bones and Joints Flashcards
What are the functions of Bone? (6 points)
- Provides a framework for the body
- Gives attachment to muscles and tendons
- Allows for movement of the body as a whole and of parts of the body by forming joints that are moved by muscles.
- Forms the boundaries of the cranial, thoratic and pelvic cavaties, protecting the organs they contain.
- haemopoiesis: the production of blood cells in red bone marrow.
- Mineral storage, especially calcium phosphate - Note: the mineral reservoir within bone is essential for maintenance of blood calciium levels, which must be tightly controlled.
What are the main types of bone? (5 points)
- Long
- Short
- Irregular
- Flat
- Sesamoid
What are the characteristics of long bones? (2 points)
- They consist of a shaft and two extremities.
2. They are longer than they are wide.
What are three examples of long bones?
- The Femur
- Tibia
- Fibula
What are the main characteristics of short, irregular, flat and sesamoid bones? (2 points)
- they have no shafts or extremities
2. they are diverse in shape and size
What is an example of a short bone?
- Carpals (wrist)
What are two examples of irregular bones?
- vertebrae
2. some skull bones
What are three examples of flat bones?
- sternum
- ribs
- most skull bones
What is an example of a sesamoid bone?
- Patella (the knee cap)
Explain the general structure of long bones and what each part is composed of. (7 points)
- They have a dia-phy-sis (Shaft) and 2 e-pip-hy-ses (Extremities).
- The Dia-phy-sis is composed of compact bone with a central medullary canal, containing fatty yellow bone marrow.
- The E-pip-hy-ses consist of an outer covering of compact bone with spongy (cancellous) bone inside.
- The Dia-phy-sis and E-pip-hy-sis are separated by e-pip-hy-seal cartilages, which ossify when growth is complete.
- They are almost completely covered (just apart from within joint cavities) by a vascular membrane, the peri-o-ste-um, which has two layers.
- The peri-o-ste-um allows attachment of tendons and is continuous with the joint capsule.
- Hy-a-line Cartilage replaces periosteum on bone surfaces that form joints.
How does thickening of a long bone occur? (1 point)
- by the deposition of new bone tissue uder the peri-o-ste-um.
What are the functions of the two layers of the Peri-o-ste-um? (2 points)
- the outer layer is tough and fibrous, and protects the bone underneath.
- the inner layer contains osteoblasts and osteoclasts, the cells responsible for bone production and breakdown. (it an important part when it comes to repair and remodelling of the bone)
Where is the blood supply to the shaft (dia-phy-sis) of long bone derived from? (1 point)
- One or more nutrient arteries
Where do the (e-pip-hy-ses) get their blood supply from? (1 point)
- They have thier own blood supply.
What are the capillary networks arising from the epiphyses and diaphysis like in mature bone? (1 point)
- Heavily interconnected.
Where does the sensory supply to long bones come from and where does it go? (2 points)
- It usually enters the bone at the same site as the nutrient artery
- and branches extensively throughout the bone.
Why is bone injury normally very painful? (1 point)
- Because of the fact that bones have a sensory supply.
What is the general structure of short, irregular, flat and sesa-moid bones? (2 points)
- They have a relatively thin outer layer of compact bone inside containing red bone marrow.
- They are enclosed by periosteum, except the inner layer of the cranial bones where it is replaced by dura matter.
What type of tissue is bone? (1 point)
- Bone is a strong and durable type of connective tissue.
Explain the microscopic structure of bone? (4 points + 2 notes)
- Primarily (i.e 65%) composed of a mixture of calcium salts, mainly calcium phosphate.
- This inorganic matrix (composed of calcium salts) gives bone great hardness (but on its own would be brittle and prone to shattering). - The remaining third of bone is organic material, called osteoid, which is composed of mainly colagen.
- Collagen is very strong and gives bone slight flexibility. - The cellular component of bone contibutes less than 2% of bone mass.
What are the cells responsible for bone formation called? and what do they secrete? (2 points)
- Osteo-blasts
2. Both the organic and inorganic componets of bone.
What do Osteo-blasts later mature into?
Osteo-cytes
What is the name of the cartilage-forming cells?
Chon-dro-cytes
What are the cells responsible for breaking down bone?
Osteo-clasts
Large multinucleate cells made from the fusuion of up to 20 monocytes
What maintains normal bone structure and functions?
A fine balance of osteo-blast and osteo-clast activity
Where do Osteo-blasts and Chon-dro-cytes develop from?
The same parent fibrous tissue cells.
Where are Osteo-blasts present? (4 points)
- In the deeper layers of periosteum
- In the centres of ossification of immature bone
- At the ends of the dia-phy-sis adjacent to the epiphyseal cartilages of long bones.
- At the site of a fracture
What are Oseo-cytes, how are they nourished and when are they formed?
- They are the mature bone cells that monitor and maintain bone tissue.
- they are nourished by tissue fulid in the canaliculi that radiate from the central canals.
- They form as bone develops and osteo-blasts become trapped within the newly formed bone.
What is the main function of osteo-clasts? and where do they carry out thier functions?
- Reabsorbtion of bone to maintain the optimum shape.
- This takes place at bone surfaces:
- Under the periosteum, to maintain the shape of bones during growth and to remove excess callus formed during healing of fractures.
- round the walls of the medullary canal during growth and to canalise callus during healing.
What is compact (cortical) bone made up of and what are the functions of these smaller parts? (6 points)
- A large number of parallel tube-shaped units called osteons (Haversian systems), each of which is made up of a central canal surrounded by a series of expanding rings, similar to the growth rings of a tree.
- These osteons tend to be aligned the same way that force is applied to the bone, so for example in the femur (thigh bone), they run from one epiphysis to the other. This gives the bone great strength. - The central canal contains nerves, lymphatics and blood vessels, and each (central canal) is linked with neighbouring canals by tunnels running at right angles between them, called perforating canals.
- The series of cylindrical plates of bone arranged around each central canal are called lamellae.
- Between adjacent lamellae of the osteon are strings of little cavities called lacunae, in each of which sits an osteocyte.
- Lacunae communicate with each other through a series of tiny channels called canaliculi, which allows the circulation of interstitial fluid through the bone, and direct contact between the osteo-cytes, which extend fine processes into them.
- Between the osteons are interstitial lamellae, the remanants of older systems partially broken down during remodelling or growth of bone.
What percent of body bone mass is made up of compact (cortical) bone?
- 80% of the body bone mass.
What does Spongy (cancellous, trabecular) bone look like?
- To the naked eye, it looks like a honeycomb.
What is spongy bone made up of?
- A framework formed from trabeculae (meaning ‘little beams’), which consist of a few lamellae and osteocytes interconnected by canaliculi.
- Osteo-cytes are nourished by interstitial fluid seeping into the bone through the tiny canaliculi.
- The spaces between the trabeculae contain red bone marrow.